Only objects that support the java.io.Serializable interface can be * written to streams. The class of each serializable object is encoded * including the class name and signature of the class, the values of the * object's fields and arrays, and the closure of any other objects referenced * from the initial objects. * *
The method writeObject is used to write an object to the stream. Any * object, including Strings and arrays, is written with writeObject. Multiple * objects or primitives can be written to the stream. The objects must be * read back from the corresponding ObjectInputstream with the same types and * in the same order as they were written. * *
Primitive data types can also be written to the stream using the * appropriate methods from DataOutput. Strings can also be written using the * writeUTF method. * *
The default serialization mechanism for an object writes the class of the * object, the class signature, and the values of all non-transient and * non-static fields. References to other objects (except in transient or * static fields) cause those objects to be written also. Multiple references * to a single object are encoded using a reference sharing mechanism so that * graphs of objects can be restored to the same shape as when the original was * written. * *
For example to write an object that can be read by the example in
* ObjectInputStream:
*
*
* FileOutputStream fos = new FileOutputStream("t.tmp");
* ObjectOutputStream oos = new ObjectOutputStream(fos);
*
* oos.writeInt(12345);
* oos.writeObject("Today");
* oos.writeObject(new Date());
*
* oos.close();
*
*
* Classes that require special handling during the serialization and
* deserialization process must implement special methods with these exact
* signatures:
*
*
* private void readObject(java.io.ObjectInputStream stream) * throws IOException, ClassNotFoundException; * private void writeObject(java.io.ObjectOutputStream stream) * throws IOException * private void readObjectNoData() * throws ObjectStreamException; ** *
The writeObject method is responsible for writing the state of the object * for its particular class so that the corresponding readObject method can * restore it. The method does not need to concern itself with the state * belonging to the object's superclasses or subclasses. State is saved by * writing the individual fields to the ObjectOutputStream using the * writeObject method or by using the methods for primitive data types * supported by DataOutput. * *
Serialization does not write out the fields of any object that does not * implement the java.io.Serializable interface. Subclasses of Objects that * are not serializable can be serializable. In this case the non-serializable * class must have a no-arg constructor to allow its fields to be initialized. * In this case it is the responsibility of the subclass to save and restore * the state of the non-serializable class. It is frequently the case that the * fields of that class are accessible (public, package, or protected) or that * there are get and set methods that can be used to restore the state. * *
Serialization of an object can be prevented by implementing writeObject * and readObject methods that throw the NotSerializableException. The * exception will be caught by the ObjectOutputStream and abort the * serialization process. * *
Implementing the Externalizable interface allows the object to assume * complete control over the contents and format of the object's serialized * form. The methods of the Externalizable interface, writeExternal and * readExternal, are called to save and restore the objects state. When * implemented by a class they can write and read their own state using all of * the methods of ObjectOutput and ObjectInput. It is the responsibility of * the objects to handle any versioning that occurs. * *
Enum constants are serialized differently than ordinary serializable or * externalizable objects. The serialized form of an enum constant consists * solely of its name; field values of the constant are not transmitted. To * serialize an enum constant, ObjectOutputStream writes the string returned by * the constant's name method. Like other serializable or externalizable * objects, enum constants can function as the targets of back references * appearing subsequently in the serialization stream. The process by which * enum constants are serialized cannot be customized; any class-specific * writeObject and writeReplace methods defined by enum types are ignored * during serialization. Similarly, any serialPersistentFields or * serialVersionUID field declarations are also ignored--all enum types have a * fixed serialVersionUID of 0L. * *
Primitive data, excluding serializable fields and externalizable data, is
* written to the ObjectOutputStream in block-data records. A block data record
* is composed of a header and data. The block data header consists of a marker
* and the number of bytes to follow the header. Consecutive primitive data
* writes are merged into one block-data record. The blocking factor used for
* a block-data record will be 1024 bytes. Each block-data record will be
* filled up to 1024 bytes, or be written whenever there is a termination of
* block-data mode. Calls to the ObjectOutputStream methods writeObject,
* defaultWriteObject and writeFields initially terminate any existing
* block-data record.
*
* @author Mike Warres
* @author Roger Riggs
* @see java.io.DataOutput
* @see java.io.ObjectInputStream
* @see java.io.Serializable
* @see java.io.Externalizable
* @see Object Serialization Specification, Section 2, Object Output Classes
* @since JDK1.1
*/
public class ObjectOutputStream
extends OutputStream implements ObjectOutput, ObjectStreamConstants
{
private static class Caches {
/** cache of subclass security audit results */
static final ConcurrentMap If a security manager is installed, this constructor will check for
* the "enableSubclassImplementation" SerializablePermission when invoked
* directly or indirectly by the constructor of a subclass which overrides
* the ObjectOutputStream.putFields or ObjectOutputStream.writeUnshared
* methods.
*
* @param out output stream to write to
* @throws IOException if an I/O error occurs while writing stream header
* @throws SecurityException if untrusted subclass illegally overrides
* security-sensitive methods
* @throws NullPointerException if If there is a security manager installed, this method first calls the
* security manager's This routine provides a hook to enable the current version of
* Serialization to write in a format that is backwards compatible to a
* previous version of the stream format.
*
* Every effort will be made to avoid introducing additional
* backwards incompatibilities; however, sometimes there is no
* other alternative.
*
* @param version use ProtocolVersion from java.io.ObjectStreamConstants.
* @throws IllegalStateException if called after any objects
* have been serialized.
* @throws IllegalArgumentException if invalid version is passed in.
* @throws IOException if I/O errors occur
* @see java.io.ObjectStreamConstants#PROTOCOL_VERSION_1
* @see java.io.ObjectStreamConstants#PROTOCOL_VERSION_2
* @since 1.2
*/
public void useProtocolVersion(int version) throws IOException {
if (handles.size() != 0) {
// REMIND: implement better check for pristine stream?
throw new IllegalStateException("stream non-empty");
}
switch (version) {
case PROTOCOL_VERSION_1:
case PROTOCOL_VERSION_2:
protocol = version;
break;
default:
throw new IllegalArgumentException(
"unknown version: " + version);
}
}
/**
* Write the specified object to the ObjectOutputStream. The class of the
* object, the signature of the class, and the values of the non-transient
* and non-static fields of the class and all of its supertypes are
* written. Default serialization for a class can be overridden using the
* writeObject and the readObject methods. Objects referenced by this
* object are written transitively so that a complete equivalent graph of
* objects can be reconstructed by an ObjectInputStream.
*
* Exceptions are thrown for problems with the OutputStream and for
* classes that should not be serialized. All exceptions are fatal to the
* OutputStream, which is left in an indeterminate state, and it is up to
* the caller to ignore or recover the stream state.
*
* @throws InvalidClassException Something is wrong with a class used by
* serialization.
* @throws NotSerializableException Some object to be serialized does not
* implement the java.io.Serializable interface.
* @throws IOException Any exception thrown by the underlying
* OutputStream.
*/
public final void writeObject(Object obj) throws IOException {
if (enableOverride) {
writeObjectOverride(obj);
return;
}
try {
writeObject0(obj, false);
} catch (IOException ex) {
if (depth == 0) {
// BEGIN Android-changed
// writeFatalException(ex);
try {
writeFatalException(ex);
} catch (IOException ex2) {
// If writing the exception to the output stream causes another exception there
// is no need to propagate the second exception or generate a third exception,
// both of which might obscure details of the root cause.
}
// END Android-changed
}
throw ex;
}
}
/**
* Method used by subclasses to override the default writeObject method.
* This method is called by trusted subclasses of ObjectInputStream that
* constructed ObjectInputStream using the protected no-arg constructor.
* The subclass is expected to provide an override method with the modifier
* "final".
*
* @param obj object to be written to the underlying stream
* @throws IOException if there are I/O errors while writing to the
* underlying stream
* @see #ObjectOutputStream()
* @see #writeObject(Object)
* @since 1.2
*/
protected void writeObjectOverride(Object obj) throws IOException {
// BEGIN Android-changed
if (!enableOverride) {
// Subclasses must override.
throw new IOException();
}
// END Android-changed
}
/**
* Writes an "unshared" object to the ObjectOutputStream. This method is
* identical to writeObject, except that it always writes the given object
* as a new, unique object in the stream (as opposed to a back-reference
* pointing to a previously serialized instance). Specifically:
* ObjectOutputStream subclasses which override this method can only be
* constructed in security contexts possessing the
* "enableSubclassImplementation" SerializablePermission; any attempt to
* instantiate such a subclass without this permission will cause a
* SecurityException to be thrown.
*
* @param obj object to write to stream
* @throws NotSerializableException if an object in the graph to be
* serialized does not implement the Serializable interface
* @throws InvalidClassException if a problem exists with the class of an
* object to be serialized
* @throws IOException if an I/O error occurs during serialization
* @since 1.4
*/
public void writeUnshared(Object obj) throws IOException {
try {
writeObject0(obj, true);
} catch (IOException ex) {
if (depth == 0) {
writeFatalException(ex);
}
throw ex;
}
}
/**
* Write the non-static and non-transient fields of the current class to
* this stream. This may only be called from the writeObject method of the
* class being serialized. It will throw the NotActiveException if it is
* called otherwise.
*
* @throws IOException if I/O errors occur while writing to the underlying
* This method is called exactly once for each unique proxy class
* descriptor in the stream. The default implementation of this method in
* The corresponding method in The ObjectOutputStream.writeObject method takes a parameter of type
* Object (as opposed to type Serializable) to allow for cases where
* non-serializable objects are replaced by serializable ones.
*
* When a subclass is replacing objects it must insure that either a
* complementary substitution must be made during deserialization or that
* the substituted object is compatible with every field where the
* reference will be stored. Objects whose type is not a subclass of the
* type of the field or array element abort the serialization by raising an
* exception and the object is not be stored.
*
* This method is called only once when each object is first
* encountered. All subsequent references to the object will be redirected
* to the new object. This method should return the object to be
* substituted or the original object.
*
* Null can be returned as the object to be substituted, but may cause
* NullReferenceException in classes that contain references to the
* original object since they may be expecting an object instead of
* null.
*
* @param obj the object to be replaced
* @return the alternate object that replaced the specified one
* @throws IOException Any exception thrown by the underlying
* OutputStream.
*/
protected Object replaceObject(Object obj) throws IOException {
return obj;
}
/**
* Enable the stream to do replacement of objects in the stream. When
* enabled, the replaceObject method is called for every object being
* serialized.
*
* If Note that this method will only be called if the ObjectOutputStream
* is not using the old serialization stream format (set by calling
* ObjectOutputStream's This will be set back to false when a warning is logged to ensure that the log is not
* flooded with warnings.
*
* http://b/28159133
*/
private boolean warnOnceWhenWriting;
/**
* Creates new BlockDataOutputStream on top of given underlying stream.
* Block data mode is turned off by default.
*/
BlockDataOutputStream(OutputStream out) {
this.out = out;
dout = new DataOutputStream(this);
}
/**
* Sets block data mode to the given mode (true == on, false == off)
* and returns the previous mode value. If the new mode is the same as
* the old mode, no action is taken. If the new mode differs from the
* old mode, any buffered data is flushed before switching to the new
* mode.
*/
boolean setBlockDataMode(boolean mode) throws IOException {
if (blkmode == mode) {
return blkmode;
}
drain();
blkmode = mode;
return !blkmode;
}
/**
* Returns true if the stream is currently in block data mode, false
* otherwise.
*/
boolean getBlockDataMode() {
return blkmode;
}
/**
* Warns if the stream has been closed.
*
* This is called after data has been written to the underlying stream in order to allow
* the underlying stream to detect and fail if an attempt is made to write to a closed
* stream. That ensures that this will only log a warning if the underlying stream does not
* so it will not log unnecessary warnings.
*/
private void warnIfClosed() {
if (warnOnceWhenWriting) {
System.logW("The app is relying on undefined behavior. Attempting to write to a"
+ " closed ObjectOutputStream could produce corrupt output in a future"
+ " release of Android.", new IOException("Stream Closed"));
// Set back to false so no more messages are logged unless the stream is closed
// again.
warnOnceWhenWriting = false;
}
}
/* ----------------- generic output stream methods ----------------- */
/*
* The following methods are equivalent to their counterparts in
* OutputStream, except that they partition written data into data
* blocks when in block data mode.
*/
public void write(int b) throws IOException {
if (pos >= MAX_BLOCK_SIZE) {
drain();
}
buf[pos++] = (byte) b;
}
public void write(byte[] b) throws IOException {
write(b, 0, b.length, false);
}
public void write(byte[] b, int off, int len) throws IOException {
write(b, off, len, false);
}
public void flush() throws IOException {
drain();
out.flush();
}
public void close() throws IOException {
flush();
out.close();
warnOnceWhenWriting = true;
}
/**
* Writes specified span of byte values from given array. If copy is
* true, copies the values to an intermediate buffer before writing
* them to underlying stream (to avoid exposing a reference to the
* original byte array).
*/
void write(byte[] b, int off, int len, boolean copy)
throws IOException
{
if (!(copy || blkmode)) { // write directly
drain();
out.write(b, off, len);
warnIfClosed();
return;
}
while (len > 0) {
if (pos >= MAX_BLOCK_SIZE) {
drain();
}
if (len >= MAX_BLOCK_SIZE && !copy && pos == 0) {
// avoid unnecessary copy
writeBlockHeader(MAX_BLOCK_SIZE);
out.write(b, off, MAX_BLOCK_SIZE);
off += MAX_BLOCK_SIZE;
len -= MAX_BLOCK_SIZE;
} else {
int wlen = Math.min(len, MAX_BLOCK_SIZE - pos);
System.arraycopy(b, off, buf, pos, wlen);
pos += wlen;
off += wlen;
len -= wlen;
}
}
warnIfClosed();
}
/**
* Writes all buffered data from this stream to the underlying stream,
* but does not flush underlying stream.
*/
void drain() throws IOException {
if (pos == 0) {
return;
}
if (blkmode) {
writeBlockHeader(pos);
}
out.write(buf, 0, pos);
pos = 0;
warnIfClosed();
}
/**
* Writes block data header. Data blocks shorter than 256 bytes are
* prefixed with a 2-byte header; all others start with a 5-byte
* header.
*/
private void writeBlockHeader(int len) throws IOException {
if (len <= 0xFF) {
hbuf[0] = TC_BLOCKDATA;
hbuf[1] = (byte) len;
out.write(hbuf, 0, 2);
} else {
hbuf[0] = TC_BLOCKDATALONG;
Bits.putInt(hbuf, 1, len);
out.write(hbuf, 0, 5);
}
warnIfClosed();
}
/* ----------------- primitive data output methods ----------------- */
/*
* The following methods are equivalent to their counterparts in
* DataOutputStream, except that they partition written data into data
* blocks when in block data mode.
*/
public void writeBoolean(boolean v) throws IOException {
if (pos >= MAX_BLOCK_SIZE) {
drain();
}
Bits.putBoolean(buf, pos++, v);
}
public void writeByte(int v) throws IOException {
if (pos >= MAX_BLOCK_SIZE) {
drain();
}
buf[pos++] = (byte) v;
}
public void writeChar(int v) throws IOException {
if (pos + 2 <= MAX_BLOCK_SIZE) {
Bits.putChar(buf, pos, (char) v);
pos += 2;
} else {
dout.writeChar(v);
}
}
public void writeShort(int v) throws IOException {
if (pos + 2 <= MAX_BLOCK_SIZE) {
Bits.putShort(buf, pos, (short) v);
pos += 2;
} else {
dout.writeShort(v);
}
}
public void writeInt(int v) throws IOException {
if (pos + 4 <= MAX_BLOCK_SIZE) {
Bits.putInt(buf, pos, v);
pos += 4;
} else {
dout.writeInt(v);
}
}
public void writeFloat(float v) throws IOException {
if (pos + 4 <= MAX_BLOCK_SIZE) {
Bits.putFloat(buf, pos, v);
pos += 4;
} else {
dout.writeFloat(v);
}
}
public void writeLong(long v) throws IOException {
if (pos + 8 <= MAX_BLOCK_SIZE) {
Bits.putLong(buf, pos, v);
pos += 8;
} else {
dout.writeLong(v);
}
}
public void writeDouble(double v) throws IOException {
if (pos + 8 <= MAX_BLOCK_SIZE) {
Bits.putDouble(buf, pos, v);
pos += 8;
} else {
dout.writeDouble(v);
}
}
public void writeBytes(String s) throws IOException {
int endoff = s.length();
int cpos = 0;
int csize = 0;
for (int off = 0; off < endoff; ) {
if (cpos >= csize) {
cpos = 0;
csize = Math.min(endoff - off, CHAR_BUF_SIZE);
s.getChars(off, off + csize, cbuf, 0);
}
if (pos >= MAX_BLOCK_SIZE) {
drain();
}
int n = Math.min(csize - cpos, MAX_BLOCK_SIZE - pos);
int stop = pos + n;
while (pos < stop) {
buf[pos++] = (byte) cbuf[cpos++];
}
off += n;
}
}
public void writeChars(String s) throws IOException {
int endoff = s.length();
for (int off = 0; off < endoff; ) {
int csize = Math.min(endoff - off, CHAR_BUF_SIZE);
s.getChars(off, off + csize, cbuf, 0);
writeChars(cbuf, 0, csize);
off += csize;
}
}
public void writeUTF(String s) throws IOException {
writeUTF(s, getUTFLength(s));
}
/* -------------- primitive data array output methods -------------- */
/*
* The following methods write out spans of primitive data values.
* Though equivalent to calling the corresponding primitive write
* methods repeatedly, these methods are optimized for writing groups
* of primitive data values more efficiently.
*/
void writeBooleans(boolean[] v, int off, int len) throws IOException {
int endoff = off + len;
while (off < endoff) {
if (pos >= MAX_BLOCK_SIZE) {
drain();
}
int stop = Math.min(endoff, off + (MAX_BLOCK_SIZE - pos));
while (off < stop) {
Bits.putBoolean(buf, pos++, v[off++]);
}
}
}
void writeChars(char[] v, int off, int len) throws IOException {
int limit = MAX_BLOCK_SIZE - 2;
int endoff = off + len;
while (off < endoff) {
if (pos <= limit) {
int avail = (MAX_BLOCK_SIZE - pos) >> 1;
int stop = Math.min(endoff, off + avail);
while (off < stop) {
Bits.putChar(buf, pos, v[off++]);
pos += 2;
}
} else {
dout.writeChar(v[off++]);
}
}
}
void writeShorts(short[] v, int off, int len) throws IOException {
int limit = MAX_BLOCK_SIZE - 2;
int endoff = off + len;
while (off < endoff) {
if (pos <= limit) {
int avail = (MAX_BLOCK_SIZE - pos) >> 1;
int stop = Math.min(endoff, off + avail);
while (off < stop) {
Bits.putShort(buf, pos, v[off++]);
pos += 2;
}
} else {
dout.writeShort(v[off++]);
}
}
}
void writeInts(int[] v, int off, int len) throws IOException {
int limit = MAX_BLOCK_SIZE - 4;
int endoff = off + len;
while (off < endoff) {
if (pos <= limit) {
int avail = (MAX_BLOCK_SIZE - pos) >> 2;
int stop = Math.min(endoff, off + avail);
while (off < stop) {
Bits.putInt(buf, pos, v[off++]);
pos += 4;
}
} else {
dout.writeInt(v[off++]);
}
}
}
void writeFloats(float[] v, int off, int len) throws IOException {
int limit = MAX_BLOCK_SIZE - 4;
int endoff = off + len;
while (off < endoff) {
if (pos <= limit) {
int avail = (MAX_BLOCK_SIZE - pos) >> 2;
int chunklen = Math.min(endoff - off, avail);
floatsToBytes(v, off, buf, pos, chunklen);
off += chunklen;
pos += chunklen << 2;
} else {
dout.writeFloat(v[off++]);
}
}
}
void writeLongs(long[] v, int off, int len) throws IOException {
int limit = MAX_BLOCK_SIZE - 8;
int endoff = off + len;
while (off < endoff) {
if (pos <= limit) {
int avail = (MAX_BLOCK_SIZE - pos) >> 3;
int stop = Math.min(endoff, off + avail);
while (off < stop) {
Bits.putLong(buf, pos, v[off++]);
pos += 8;
}
} else {
dout.writeLong(v[off++]);
}
}
}
void writeDoubles(double[] v, int off, int len) throws IOException {
int limit = MAX_BLOCK_SIZE - 8;
int endoff = off + len;
while (off < endoff) {
if (pos <= limit) {
int avail = (MAX_BLOCK_SIZE - pos) >> 3;
int chunklen = Math.min(endoff - off, avail);
doublesToBytes(v, off, buf, pos, chunklen);
off += chunklen;
pos += chunklen << 3;
} else {
dout.writeDouble(v[off++]);
}
}
}
/**
* Returns the length in bytes of the UTF encoding of the given string.
*/
long getUTFLength(String s) {
int len = s.length();
long utflen = 0;
for (int off = 0; off < len; ) {
int csize = Math.min(len - off, CHAR_BUF_SIZE);
s.getChars(off, off + csize, cbuf, 0);
for (int cpos = 0; cpos < csize; cpos++) {
char c = cbuf[cpos];
if (c >= 0x0001 && c <= 0x007F) {
utflen++;
} else if (c > 0x07FF) {
utflen += 3;
} else {
utflen += 2;
}
}
off += csize;
}
return utflen;
}
/**
* Writes the given string in UTF format. This method is used in
* situations where the UTF encoding length of the string is already
* known; specifying it explicitly avoids a prescan of the string to
* determine its UTF length.
*/
void writeUTF(String s, long utflen) throws IOException {
if (utflen > 0xFFFFL) {
throw new UTFDataFormatException();
}
writeShort((int) utflen);
if (utflen == (long) s.length()) {
writeBytes(s);
} else {
writeUTFBody(s);
}
}
/**
* Writes given string in "long" UTF format. "Long" UTF format is
* identical to standard UTF, except that it uses an 8 byte header
* (instead of the standard 2 bytes) to convey the UTF encoding length.
*/
void writeLongUTF(String s) throws IOException {
writeLongUTF(s, getUTFLength(s));
}
/**
* Writes given string in "long" UTF format, where the UTF encoding
* length of the string is already known.
*/
void writeLongUTF(String s, long utflen) throws IOException {
writeLong(utflen);
if (utflen == (long) s.length()) {
writeBytes(s);
} else {
writeUTFBody(s);
}
}
/**
* Writes the "body" (i.e., the UTF representation minus the 2-byte or
* 8-byte length header) of the UTF encoding for the given string.
*/
private void writeUTFBody(String s) throws IOException {
int limit = MAX_BLOCK_SIZE - 3;
int len = s.length();
for (int off = 0; off < len; ) {
int csize = Math.min(len - off, CHAR_BUF_SIZE);
s.getChars(off, off + csize, cbuf, 0);
for (int cpos = 0; cpos < csize; cpos++) {
char c = cbuf[cpos];
if (pos <= limit) {
if (c <= 0x007F && c != 0) {
buf[pos++] = (byte) c;
} else if (c > 0x07FF) {
buf[pos + 2] = (byte) (0x80 | ((c >> 0) & 0x3F));
buf[pos + 1] = (byte) (0x80 | ((c >> 6) & 0x3F));
buf[pos + 0] = (byte) (0xE0 | ((c >> 12) & 0x0F));
pos += 3;
} else {
buf[pos + 1] = (byte) (0x80 | ((c >> 0) & 0x3F));
buf[pos + 0] = (byte) (0xC0 | ((c >> 6) & 0x1F));
pos += 2;
}
} else { // write one byte at a time to normalize block
if (c <= 0x007F && c != 0) {
write(c);
} else if (c > 0x07FF) {
write(0xE0 | ((c >> 12) & 0x0F));
write(0x80 | ((c >> 6) & 0x3F));
write(0x80 | ((c >> 0) & 0x3F));
} else {
write(0xC0 | ((c >> 6) & 0x1F));
write(0x80 | ((c >> 0) & 0x3F));
}
}
}
off += csize;
}
}
}
/**
* Lightweight identity hash table which maps objects to integer handles,
* assigned in ascending order.
*/
private static class HandleTable {
/* number of mappings in table/next available handle */
private int size;
/* size threshold determining when to expand hash spine */
private int threshold;
/* factor for computing size threshold */
private final float loadFactor;
/* maps hash value -> candidate handle value */
private int[] spine;
/* maps handle value -> next candidate handle value */
private int[] next;
/* maps handle value -> associated object */
private Object[] objs;
/**
* Creates new HandleTable with given capacity and load factor.
*/
HandleTable(int initialCapacity, float loadFactor) {
this.loadFactor = loadFactor;
spine = new int[initialCapacity];
next = new int[initialCapacity];
objs = new Object[initialCapacity];
threshold = (int) (initialCapacity * loadFactor);
clear();
}
/**
* Assigns next available handle to given object, and returns handle
* value. Handles are assigned in ascending order starting at 0.
*/
int assign(Object obj) {
if (size >= next.length) {
growEntries();
}
if (size >= threshold) {
growSpine();
}
insert(obj, size);
return size++;
}
/**
* Looks up and returns handle associated with given object, or -1 if
* no mapping found.
*/
int lookup(Object obj) {
if (size == 0) {
return -1;
}
int index = hash(obj) % spine.length;
for (int i = spine[index]; i >= 0; i = next[i]) {
if (objs[i] == obj) {
return i;
}
}
return -1;
}
/**
* Resets table to its initial (empty) state.
*/
void clear() {
Arrays.fill(spine, -1);
Arrays.fill(objs, 0, size, null);
size = 0;
}
/**
* Returns the number of mappings currently in table.
*/
int size() {
return size;
}
/**
* Inserts mapping object -> handle mapping into table. Assumes table
* is large enough to accommodate new mapping.
*/
private void insert(Object obj, int handle) {
int index = hash(obj) % spine.length;
objs[handle] = obj;
next[handle] = spine[index];
spine[index] = handle;
}
/**
* Expands the hash "spine" -- equivalent to increasing the number of
* buckets in a conventional hash table.
*/
private void growSpine() {
spine = new int[(spine.length << 1) + 1];
threshold = (int) (spine.length * loadFactor);
Arrays.fill(spine, -1);
for (int i = 0; i < size; i++) {
insert(objs[i], i);
}
}
/**
* Increases hash table capacity by lengthening entry arrays.
*/
private void growEntries() {
int newLength = (next.length << 1) + 1;
int[] newNext = new int[newLength];
System.arraycopy(next, 0, newNext, 0, size);
next = newNext;
Object[] newObjs = new Object[newLength];
System.arraycopy(objs, 0, newObjs, 0, size);
objs = newObjs;
}
/**
* Returns hash value for given object.
*/
private int hash(Object obj) {
return System.identityHashCode(obj) & 0x7FFFFFFF;
}
}
/**
* Lightweight identity hash table which maps objects to replacement
* objects.
*/
private static class ReplaceTable {
/* maps object -> index */
private final HandleTable htab;
/* maps index -> replacement object */
private Object[] reps;
/**
* Creates new ReplaceTable with given capacity and load factor.
*/
ReplaceTable(int initialCapacity, float loadFactor) {
htab = new HandleTable(initialCapacity, loadFactor);
reps = new Object[initialCapacity];
}
/**
* Enters mapping from object to replacement object.
*/
void assign(Object obj, Object rep) {
int index = htab.assign(obj);
while (index >= reps.length) {
grow();
}
reps[index] = rep;
}
/**
* Looks up and returns replacement for given object. If no
* replacement is found, returns the lookup object itself.
*/
Object lookup(Object obj) {
int index = htab.lookup(obj);
return (index >= 0) ? reps[index] : obj;
}
/**
* Resets table to its initial (empty) state.
*/
void clear() {
Arrays.fill(reps, 0, htab.size(), null);
htab.clear();
}
/**
* Returns the number of mappings currently in table.
*/
int size() {
return htab.size();
}
/**
* Increases table capacity.
*/
private void grow() {
Object[] newReps = new Object[(reps.length << 1) + 1];
System.arraycopy(reps, 0, newReps, 0, reps.length);
reps = newReps;
}
}
/**
* Stack to keep debug information about the state of the
* serialization process, for embedding in exception messages.
*/
private static class DebugTraceInfoStack {
private final Listout is null
* @since 1.4
* @see ObjectOutputStream#ObjectOutputStream()
* @see ObjectOutputStream#putFields()
* @see ObjectInputStream#ObjectInputStream(InputStream)
*/
public ObjectOutputStream(OutputStream out) throws IOException {
verifySubclass();
bout = new BlockDataOutputStream(out);
handles = new HandleTable(10, (float) 3.00);
subs = new ReplaceTable(10, (float) 3.00);
enableOverride = false;
writeStreamHeader();
bout.setBlockDataMode(true);
if (extendedDebugInfo) {
debugInfoStack = new DebugTraceInfoStack();
} else {
debugInfoStack = null;
}
}
/**
* Provide a way for subclasses that are completely reimplementing
* ObjectOutputStream to not have to allocate private data just used by
* this implementation of ObjectOutputStream.
*
* checkPermission method with a
* SerializablePermission("enableSubclassImplementation")
* permission to ensure it's ok to enable subclassing.
*
* @throws SecurityException if a security manager exists and its
* checkPermission method denies enabling
* subclassing.
* @throws IOException if an I/O error occurs while creating this stream
* @see SecurityManager#checkPermission
* @see java.io.SerializablePermission
*/
protected ObjectOutputStream() throws IOException, SecurityException {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
}
bout = null;
handles = null;
subs = null;
enableOverride = true;
debugInfoStack = null;
}
/**
* Specify stream protocol version to use when writing the stream.
*
*
*
* While writing an object via writeUnshared does not in itself guarantee a
* unique reference to the object when it is deserialized, it allows a
* single object to be defined multiple times in a stream, so that multiple
* calls to readUnshared by the receiver will not conflict. Note that the
* rules described above only apply to the base-level object written with
* writeUnshared, and not to any transitively referenced sub-objects in the
* object graph to be serialized.
*
* OutputStream
*/
public void defaultWriteObject() throws IOException {
SerialCallbackContext ctx = curContext;
if (ctx == null) {
throw new NotActiveException("not in call to writeObject");
}
Object curObj = ctx.getObj();
ObjectStreamClass curDesc = ctx.getDesc();
bout.setBlockDataMode(false);
defaultWriteFields(curObj, curDesc);
bout.setBlockDataMode(true);
}
/**
* Retrieve the object used to buffer persistent fields to be written to
* the stream. The fields will be written to the stream when writeFields
* method is called.
*
* @return an instance of the class Putfield that holds the serializable
* fields
* @throws IOException if I/O errors occur
* @since 1.2
*/
public ObjectOutputStream.PutField putFields() throws IOException {
if (curPut == null) {
SerialCallbackContext ctx = curContext;
if (ctx == null) {
throw new NotActiveException("not in call to writeObject");
}
Object curObj = ctx.getObj();
ObjectStreamClass curDesc = ctx.getDesc();
curPut = new PutFieldImpl(curDesc);
}
return curPut;
}
/**
* Write the buffered fields to the stream.
*
* @throws IOException if I/O errors occur while writing to the underlying
* stream
* @throws NotActiveException Called when a classes writeObject method was
* not called to write the state of the object.
* @since 1.2
*/
public void writeFields() throws IOException {
if (curPut == null) {
throw new NotActiveException("no current PutField object");
}
bout.setBlockDataMode(false);
curPut.writeFields();
bout.setBlockDataMode(true);
}
/**
* Reset will disregard the state of any objects already written to the
* stream. The state is reset to be the same as a new ObjectOutputStream.
* The current point in the stream is marked as reset so the corresponding
* ObjectInputStream will be reset at the same point. Objects previously
* written to the stream will not be referred to as already being in the
* stream. They will be written to the stream again.
*
* @throws IOException if reset() is invoked while serializing an object.
*/
public void reset() throws IOException {
if (depth != 0) {
throw new IOException("stream active");
}
bout.setBlockDataMode(false);
bout.writeByte(TC_RESET);
clear();
bout.setBlockDataMode(true);
}
/**
* Subclasses may implement this method to allow class data to be stored in
* the stream. By default this method does nothing. The corresponding
* method in ObjectInputStream is resolveClass. This method is called
* exactly once for each unique class in the stream. The class name and
* signature will have already been written to the stream. This method may
* make free use of the ObjectOutputStream to save any representation of
* the class it deems suitable (for example, the bytes of the class file).
* The resolveClass method in the corresponding subclass of
* ObjectInputStream must read and use any data or objects written by
* annotateClass.
*
* @param cl the class to annotate custom data for
* @throws IOException Any exception thrown by the underlying
* OutputStream.
*/
protected void annotateClass(Class cl) throws IOException {
}
/**
* Subclasses may implement this method to store custom data in the stream
* along with descriptors for dynamic proxy classes.
*
* ObjectOutputStream does nothing.
*
* ObjectInputStream is
* resolveProxyClass. For a given subclass of
* ObjectOutputStream that overrides this method, the
* resolveProxyClass method in the corresponding subclass of
* ObjectInputStream must read any data or objects written by
* annotateProxyClass.
*
* @param cl the proxy class to annotate custom data for
* @throws IOException any exception thrown by the underlying
* OutputStream
* @see ObjectInputStream#resolveProxyClass(String[])
* @since 1.3
*/
protected void annotateProxyClass(Class cl) throws IOException {
}
/**
* This method will allow trusted subclasses of ObjectOutputStream to
* substitute one object for another during serialization. Replacing
* objects is disabled until enableReplaceObject is called. The
* enableReplaceObject method checks that the stream requesting to do
* replacement can be trusted. The first occurrence of each object written
* into the serialization stream is passed to replaceObject. Subsequent
* references to the object are replaced by the object returned by the
* original call to replaceObject. To ensure that the private state of
* objects is not unintentionally exposed, only trusted streams may use
* replaceObject.
*
* enable is true, and there is a security manager
* installed, this method first calls the security manager's
* checkPermission method with a
* SerializablePermission("enableSubstitution") permission to
* ensure it's ok to enable the stream to do replacement of objects in the
* stream.
*
* @param enable boolean parameter to enable replacement of objects
* @return the previous setting before this method was invoked
* @throws SecurityException if a security manager exists and its
* checkPermission method denies enabling the stream
* to do replacement of objects in the stream.
* @see SecurityManager#checkPermission
* @see java.io.SerializablePermission
*/
protected boolean enableReplaceObject(boolean enable)
throws SecurityException
{
if (enable == enableReplace) {
return enable;
}
if (enable) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(SUBSTITUTION_PERMISSION);
}
}
enableReplace = enable;
return !enableReplace;
}
/**
* The writeStreamHeader method is provided so subclasses can append or
* prepend their own header to the stream. It writes the magic number and
* version to the stream.
*
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
protected void writeStreamHeader() throws IOException {
bout.writeShort(STREAM_MAGIC);
bout.writeShort(STREAM_VERSION);
}
/**
* Write the specified class descriptor to the ObjectOutputStream. Class
* descriptors are used to identify the classes of objects written to the
* stream. Subclasses of ObjectOutputStream may override this method to
* customize the way in which class descriptors are written to the
* serialization stream. The corresponding method in ObjectInputStream,
* readClassDescriptor, should then be overridden to
* reconstitute the class descriptor from its custom stream representation.
* By default, this method writes class descriptors according to the format
* defined in the Object Serialization specification.
*
* useProtocolVersion method). If this
* serialization stream is using the old format
* (PROTOCOL_VERSION_1), the class descriptor will be written
* internally in a manner that cannot be overridden or customized.
*
* @param desc class descriptor to write to the stream
* @throws IOException If an I/O error has occurred.
* @see java.io.ObjectInputStream#readClassDescriptor()
* @see #useProtocolVersion(int)
* @see java.io.ObjectStreamConstants#PROTOCOL_VERSION_1
* @since 1.3
*/
protected void writeClassDescriptor(ObjectStreamClass desc)
throws IOException
{
desc.writeNonProxy(this);
}
/**
* Writes a byte. This method will block until the byte is actually
* written.
*
* @param val the byte to be written to the stream
* @throws IOException If an I/O error has occurred.
*/
public void write(int val) throws IOException {
bout.write(val);
}
/**
* Writes an array of bytes. This method will block until the bytes are
* actually written.
*
* @param buf the data to be written
* @throws IOException If an I/O error has occurred.
*/
public void write(byte[] buf) throws IOException {
bout.write(buf, 0, buf.length, false);
}
/**
* Writes a sub array of bytes.
*
* @param buf the data to be written
* @param off the start offset in the data
* @param len the number of bytes that are written
* @throws IOException If an I/O error has occurred.
*/
public void write(byte[] buf, int off, int len) throws IOException {
if (buf == null) {
throw new NullPointerException();
}
int endoff = off + len;
if (off < 0 || len < 0 || endoff > buf.length || endoff < 0) {
throw new IndexOutOfBoundsException();
}
bout.write(buf, off, len, false);
}
/**
* Flushes the stream. This will write any buffered output bytes and flush
* through to the underlying stream.
*
* @throws IOException If an I/O error has occurred.
*/
public void flush() throws IOException {
bout.flush();
}
/**
* Drain any buffered data in ObjectOutputStream. Similar to flush but
* does not propagate the flush to the underlying stream.
*
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
protected void drain() throws IOException {
bout.drain();
}
/**
* Closes the stream. This method must be called to release any resources
* associated with the stream.
*
* @throws IOException If an I/O error has occurred.
*/
public void close() throws IOException {
flush();
// http://b/28159133
// clear();
bout.close();
}
/**
* Writes a boolean.
*
* @param val the boolean to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeBoolean(boolean val) throws IOException {
bout.writeBoolean(val);
}
/**
* Writes an 8 bit byte.
*
* @param val the byte value to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeByte(int val) throws IOException {
bout.writeByte(val);
}
/**
* Writes a 16 bit short.
*
* @param val the short value to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeShort(int val) throws IOException {
bout.writeShort(val);
}
/**
* Writes a 16 bit char.
*
* @param val the char value to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeChar(int val) throws IOException {
bout.writeChar(val);
}
/**
* Writes a 32 bit int.
*
* @param val the integer value to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeInt(int val) throws IOException {
bout.writeInt(val);
}
/**
* Writes a 64 bit long.
*
* @param val the long value to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeLong(long val) throws IOException {
bout.writeLong(val);
}
/**
* Writes a 32 bit float.
*
* @param val the float value to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeFloat(float val) throws IOException {
bout.writeFloat(val);
}
/**
* Writes a 64 bit double.
*
* @param val the double value to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeDouble(double val) throws IOException {
bout.writeDouble(val);
}
/**
* Writes a String as a sequence of bytes.
*
* @param str the String of bytes to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeBytes(String str) throws IOException {
bout.writeBytes(str);
}
/**
* Writes a String as a sequence of chars.
*
* @param str the String of chars to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeChars(String str) throws IOException {
bout.writeChars(str);
}
/**
* Primitive data write of this String in
* modified UTF-8
* format. Note that there is a
* significant difference between writing a String into the stream as
* primitive data or as an Object. A String instance written by writeObject
* is written into the stream as a String initially. Future writeObject()
* calls write references to the string into the stream.
*
* @param str the String to be written
* @throws IOException if I/O errors occur while writing to the underlying
* stream
*/
public void writeUTF(String str) throws IOException {
bout.writeUTF(str);
}
/**
* Provide programmatic access to the persistent fields to be written
* to ObjectOutput.
*
* @since 1.2
*/
public static abstract class PutField {
/**
* Put the value of the named boolean field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not
* boolean
*/
public abstract void put(String name, boolean val);
/**
* Put the value of the named byte field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not
* byte
*/
public abstract void put(String name, byte val);
/**
* Put the value of the named char field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not
* char
*/
public abstract void put(String name, char val);
/**
* Put the value of the named short field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not
* short
*/
public abstract void put(String name, short val);
/**
* Put the value of the named int field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not
* int
*/
public abstract void put(String name, int val);
/**
* Put the value of the named long field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not
* long
*/
public abstract void put(String name, long val);
/**
* Put the value of the named float field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not
* float
*/
public abstract void put(String name, float val);
/**
* Put the value of the named double field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not
* double
*/
public abstract void put(String name, double val);
/**
* Put the value of the named Object field into the persistent field.
*
* @param name the name of the serializable field
* @param val the value to assign to the field
* (which may be null)
* @throws IllegalArgumentException if name does not
* match the name of a serializable field for the class whose fields
* are being written, or if the type of the named field is not a
* reference type
*/
public abstract void put(String name, Object val);
/**
* Write the data and fields to the specified ObjectOutput stream,
* which must be the same stream that produced this
* PutField object.
*
* @param out the stream to write the data and fields to
* @throws IOException if I/O errors occur while writing to the
* underlying stream
* @throws IllegalArgumentException if the specified stream is not
* the same stream that produced this PutField
* object
* @deprecated This method does not write the values contained by this
* PutField object in a proper format, and may
* result in corruption of the serialization stream. The
* correct way to write PutField data is by
* calling the {@link java.io.ObjectOutputStream#writeFields()}
* method.
*/
@Deprecated
public abstract void write(ObjectOutput out) throws IOException;
}
/**
* Returns protocol version in use.
*/
int getProtocolVersion() {
return protocol;
}
/**
* Writes string without allowing it to be replaced in stream. Used by
* ObjectStreamClass to write class descriptor type strings.
*/
void writeTypeString(String str) throws IOException {
int handle;
if (str == null) {
writeNull();
} else if ((handle = handles.lookup(str)) != -1) {
writeHandle(handle);
} else {
writeString(str, false);
}
}
/**
* Verifies that this (possibly subclass) instance can be constructed
* without violating security constraints: the subclass must not override
* security-sensitive non-final methods, or else the
* "enableSubclassImplementation" SerializablePermission is checked.
*/
private void verifySubclass() {
Class cl = getClass();
if (cl == ObjectOutputStream.class) {
return;
}
SecurityManager sm = System.getSecurityManager();
if (sm == null) {
return;
}
processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
Boolean result = Caches.subclassAudits.get(key);
if (result == null) {
result = Boolean.valueOf(auditSubclass(cl));
Caches.subclassAudits.putIfAbsent(key, result);
}
if (result.booleanValue()) {
return;
}
sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
}
/**
* Performs reflective checks on given subclass to verify that it doesn't
* override security-sensitive non-final methods. Returns true if subclass
* is "safe", false otherwise.
*/
private static boolean auditSubclass(final Class subcl) {
Boolean result = AccessController.doPrivileged(
new PrivilegedAction