* Typically the packer engine is used by application developers * to deploy or host JAR files on a website. * The unpacker engine is used by deployment applications to * transform the byte-stream back to JAR format. *
* Here is an example using packer and unpacker: *
{@code
* import java.util.jar.Pack200;
* import java.util.jar.Pack200.*;
* ...
* // Create the Packer object
* Packer packer = Pack200.newPacker();
*
* // Initialize the state by setting the desired properties
* Map p = packer.properties();
* // take more time choosing codings for better compression
* p.put(Packer.EFFORT, "7"); // default is "5"
* // use largest-possible archive segments (>10% better compression).
* p.put(Packer.SEGMENT_LIMIT, "-1");
* // reorder files for better compression.
* p.put(Packer.KEEP_FILE_ORDER, Packer.FALSE);
* // smear modification times to a single value.
* p.put(Packer.MODIFICATION_TIME, Packer.LATEST);
* // ignore all JAR deflation requests,
* // transmitting a single request to use "store" mode.
* p.put(Packer.DEFLATE_HINT, Packer.FALSE);
* // discard debug attributes
* p.put(Packer.CODE_ATTRIBUTE_PFX+"LineNumberTable", Packer.STRIP);
* // throw an error if an attribute is unrecognized
* p.put(Packer.UNKNOWN_ATTRIBUTE, Packer.ERROR);
* // pass one class file uncompressed:
* p.put(Packer.PASS_FILE_PFX+0, "mutants/Rogue.class");
* try {
* JarFile jarFile = new JarFile("/tmp/testref.jar");
* FileOutputStream fos = new FileOutputStream("/tmp/test.pack");
* // Call the packer
* packer.pack(jarFile, fos);
* jarFile.close();
* fos.close();
*
* File f = new File("/tmp/test.pack");
* FileOutputStream fostream = new FileOutputStream("/tmp/test.jar");
* JarOutputStream jostream = new JarOutputStream(fostream);
* Unpacker unpacker = Pack200.newUnpacker();
* // Call the unpacker
* unpacker.unpack(f, jostream);
* // Must explicitly close the output.
* jostream.close();
* } catch (IOException ioe) {
* ioe.printStackTrace();
* }
* }
* * A Pack200 file compressed with gzip can be hosted on HTTP/1.1 web servers. * The deployment applications can use "Accept-Encoding=pack200-gzip". This * indicates to the server that the client application desires a version of * the file encoded with Pack200 and further compressed with gzip. Please * refer to Java Deployment Guide for more details and * techniques. *
* Unless otherwise noted, passing a null argument to a constructor or * method in this class will cause a {@link NullPointerException} to be thrown. * * @author John Rose * @author Kumar Srinivasan * @since 1.5 */ public abstract class Pack200 { private Pack200() {} //prevent instantiation // Static methods of the Pack200 class. /** * Obtain new instance of a class that implements Packer. *
If the system property java.util.jar.Pack200.Packer * is defined, then the value is taken to be the fully-qualified name * of a concrete implementation class, which must implement Packer. * This class is loaded and instantiated. If this process fails * then an unspecified error is thrown.
If an implementation has not been specified with the system * property, then the system-default implementation class is instantiated, * and the result is returned.
Note: The returned object is not guaranteed to operate * correctly if multiple threads use it at the same time. * A multi-threaded application should either allocate multiple * packer engines, or else serialize use of one engine with a lock. * * @return A newly allocated Packer engine. */ public synchronized static Packer newPacker() { return (Packer) newInstance(PACK_PROVIDER); } /** * Obtain new instance of a class that implements Unpacker. *
If the system property java.util.jar.Pack200.Unpacker * is defined, then the value is taken to be the fully-qualified * name of a concrete implementation class, which must implement Unpacker. * The class is loaded and instantiated. If this process fails * then an unspecified error is thrown.
If an implementation has not been specified with the * system property, then the system-default implementation class * is instantiated, and the result is returned.
Note: The returned object is not guaranteed to operate * correctly if multiple threads use it at the same time. * A multi-threaded application should either allocate multiple * unpacker engines, or else serialize use of one engine with a lock. * * @return A newly allocated Unpacker engine. */ public static Unpacker newUnpacker() { return (Unpacker) newInstance(UNPACK_PROVIDER); } // Interfaces /** * The packer engine applies various transformations to the input JAR file, * making the pack stream highly compressible by a compressor such as * gzip or zip. An instance of the engine can be obtained * using {@link #newPacker}. * The high degree of compression is achieved * by using a number of techniques described in the JSR 200 specification. * Some of the techniques are sorting, re-ordering and co-location of the * constant pool. *
* The pack engine is initialized to an initial state as described * by their properties below. * The initial state can be manipulated by getting the * engine properties (using {@link #properties}) and storing * the modified properties on the map. * The resource files will be passed through with no changes at all. * The class files will not contain identical bytes, since the unpacker * is free to change minor class file features such as constant pool order. * However, the class files will be semantically identical, * as specified in * The Java™ Virtual Machine Specification. *
* By default, the packer does not change the order of JAR elements. * Also, the modification time and deflation hint of each * JAR element is passed unchanged. * (Any other ZIP-archive information, such as extra attributes * giving Unix file permissions, are lost.) *
* Note that packing and unpacking a JAR will in general alter the * bytewise contents of classfiles in the JAR. This means that packing * and unpacking will in general invalidate any digital signatures * which rely on bytewise images of JAR elements. In order both to sign * and to pack a JAR, you must first pack and unpack the JAR to * "normalize" it, then compute signatures on the unpacked JAR elements, * and finally repack the signed JAR. * Both packing steps should * use precisely the same options, and the segment limit may also * need to be set to "-1", to prevent accidental variation of segment * boundaries as class file sizes change slightly. *
* (Here's why this works: Any reordering the packer does * of any classfile structures is idempotent, so the second packing * does not change the orderings produced by the first packing. * Also, the unpacker is guaranteed by the JSR 200 specification * to produce a specific bytewise image for any given transmission * ordering of archive elements.) *
* In order to maintain backward compatibility, the pack file's version is * set to accommodate the class files present in the input JAR file. In * other words, the pack file version will be the latest, if the class files * are the latest and conversely the pack file version will be the oldest * if the class file versions are also the oldest. For intermediate class * file versions the corresponding pack file version will be used. * For example: * If the input JAR-files are solely comprised of 1.5 (or lesser) * class files, a 1.5 compatible pack file is produced. This will also be * the case for archives that have no class files. * If the input JAR-files contains a 1.6 class file, then the pack file * version will be set to 1.6. *
* Note: Unless otherwise noted, passing a null argument to a * constructor or method in this class will cause a {@link NullPointerException} * to be thrown. *
* @since 1.5 */ public interface Packer { /** * This property is a numeral giving the estimated target size N * (in bytes) of each archive segment. * If a single input file requires more than N bytes, * it will be given its own archive segment. *
* As a special case, a value of -1 will produce a single large * segment with all input files, while a value of 0 will * produce one segment for each class. * Larger archive segments result in less fragmentation and * better compression, but processing them requires more memory. *
* The size of each segment is estimated by counting the size of each * input file to be transmitted in the segment, along with the size * of its name and other transmitted properties. *
* The default is -1, which means the packer will always create a single * segment output file. In cases where extremely large output files are * generated, users are strongly encouraged to use segmenting or break * up the input file into smaller JARs. *
* A 10Mb JAR packed without this limit will * typically pack about 10% smaller, but the packer may require * a larger Java heap (about ten times the segment limit). */ String SEGMENT_LIMIT = "pack.segment.limit"; /** * If this property is set to {@link #TRUE}, the packer will transmit * all elements in their original order within the source archive. *
* If it is set to {@link #FALSE}, the packer may reorder elements, * and also remove JAR directory entries, which carry no useful * information for Java applications. * (Typically this enables better compression.) *
* The default is {@link #TRUE}, which preserves the input information, * but may cause the transmitted archive to be larger than necessary. */ String KEEP_FILE_ORDER = "pack.keep.file.order"; /** * If this property is set to a single decimal digit, the packer will * use the indicated amount of effort in compressing the archive. * Level 1 may produce somewhat larger size and faster compression speed, * while level 9 will take much longer but may produce better compression. *
* The special value 0 instructs the packer to copy through the * original JAR file directly, with no compression. The JSR 200 * standard requires any unpacker to understand this special case * as a pass-through of the entire archive. *
* The default is 5, investing a modest amount of time to * produce reasonable compression. */ String EFFORT = "pack.effort"; /** * If this property is set to {@link #TRUE} or {@link #FALSE}, the packer * will set the deflation hint accordingly in the output archive, and * will not transmit the individual deflation hints of archive elements. *
* If this property is set to the special string {@link #KEEP}, the packer * will attempt to determine an independent deflation hint for each * available element of the input archive, and transmit this hint separately. *
* The default is {@link #KEEP}, which preserves the input information, * but may cause the transmitted archive to be larger than necessary. *
* It is up to the unpacker implementation * to take action upon the hint to suitably compress the elements of * the resulting unpacked jar. *
* The deflation hint of a ZIP or JAR element indicates * whether the element was deflated or stored directly. */ String DEFLATE_HINT = "pack.deflate.hint"; /** * If this property is set to the special string {@link #LATEST}, * the packer will attempt to determine the latest modification time, * among all the available entries in the original archive or the latest * modification time of all the available entries in each segment. * This single value will be transmitted as part of the segment and applied * to all the entries in each segment, {@link #SEGMENT_LIMIT}. *
* This can marginally decrease the transmitted size of the * archive, at the expense of setting all installed files to a single * date. *
* If this property is set to the special string {@link #KEEP}, * the packer transmits a separate modification time for each input * element. *
* The default is {@link #KEEP}, which preserves the input information, * but may cause the transmitted archive to be larger than necessary. *
* It is up to the unpacker implementation to take action to suitably * set the modification time of each element of its output file. * @see #SEGMENT_LIMIT */ String MODIFICATION_TIME = "pack.modification.time"; /** * Indicates that a file should be passed through bytewise, with no * compression. Multiple files may be specified by specifying * additional properties with distinct strings appended, to * make a family of properties with the common prefix. *
* There is no pathname transformation, except * that the system file separator is replaced by the JAR file * separator '/'. *
* The resulting file names must match exactly as strings with their * occurrences in the JAR file. *
* If a property value is a directory name, all files under that * directory will be passed also. *
* Examples: *
{@code
* Map p = packer.properties();
* p.put(PASS_FILE_PFX+0, "mutants/Rogue.class");
* p.put(PASS_FILE_PFX+1, "mutants/Wolverine.class");
* p.put(PASS_FILE_PFX+2, "mutants/Storm.class");
* # Pass all files in an entire directory hierarchy:
* p.put(PASS_FILE_PFX+3, "police/");
* }
*/
String PASS_FILE_PFX = "pack.pass.file.";
/// Attribute control.
/**
* Indicates the action to take when a class-file containing an unknown
* attribute is encountered. Possible values are the strings {@link #ERROR},
* {@link #STRIP}, and {@link #PASS}.
*
* The string {@link #ERROR} means that the pack operation
* as a whole will fail, with an exception of type IOException.
* The string
* {@link #STRIP} means that the attribute will be dropped.
* The string
* {@link #PASS} means that the whole class-file will be passed through
* (as if it were a resource file) without compression, with a suitable warning.
* This is the default value for this property.
*
* Examples: *
{@code
* Map p = pack200.getProperties();
* p.put(UNKNOWN_ATTRIBUTE, ERROR);
* p.put(UNKNOWN_ATTRIBUTE, STRIP);
* p.put(UNKNOWN_ATTRIBUTE, PASS);
* }
*/
String UNKNOWN_ATTRIBUTE = "pack.unknown.attribute";
/**
* When concatenated with a class attribute name,
* indicates the format of that attribute,
* using the layout language specified in the JSR 200 specification.
*
* For example, the effect of this option is built in:
* pack.class.attribute.SourceFile=RUH.
*
* The special strings {@link #ERROR}, {@link #STRIP}, and {@link #PASS} are * also allowed, with the same meaning as {@link #UNKNOWN_ATTRIBUTE}. * This provides a way for users to request that specific attributes be * refused, stripped, or passed bitwise (with no class compression). *
* Code like this might be used to support attributes for JCOV: *
* Map p = packer.properties();
* p.put(CODE_ATTRIBUTE_PFX+"CoverageTable", "NH[PHHII]");
* p.put(CODE_ATTRIBUTE_PFX+"CharacterRangeTable", "NH[PHPOHIIH]");
* p.put(CLASS_ATTRIBUTE_PFX+"SourceID", "RUH");
* p.put(CLASS_ATTRIBUTE_PFX+"CompilationID", "RUH");
* * Code like this might be used to strip debugging attributes: *
* Map p = packer.properties();
* p.put(CODE_ATTRIBUTE_PFX+"LineNumberTable", STRIP);
* p.put(CODE_ATTRIBUTE_PFX+"LocalVariableTable", STRIP);
* p.put(CLASS_ATTRIBUTE_PFX+"SourceFile", STRIP);
* pack.field.attribute.Deprecated=.
* The special strings {@link #ERROR}, {@link #STRIP}, and
* {@link #PASS} are also allowed.
* @see #CLASS_ATTRIBUTE_PFX
*/
String FIELD_ATTRIBUTE_PFX = "pack.field.attribute.";
/**
* When concatenated with a method attribute name,
* indicates the format of that attribute.
* For example, the effect of this option is built in:
* pack.method.attribute.Exceptions=NH[RCH].
* The special strings {@link #ERROR}, {@link #STRIP}, and {@link #PASS}
* are also allowed.
* @see #CLASS_ATTRIBUTE_PFX
*/
String METHOD_ATTRIBUTE_PFX = "pack.method.attribute.";
/**
* When concatenated with a code attribute name,
* indicates the format of that attribute.
* For example, the effect of this option is built in:
* pack.code.attribute.LocalVariableTable=NH[PHOHRUHRSHH].
* The special strings {@link #ERROR}, {@link #STRIP}, and {@link #PASS}
* are also allowed.
* @see #CLASS_ATTRIBUTE_PFX
*/
String CODE_ATTRIBUTE_PFX = "pack.code.attribute.";
/**
* The unpacker's progress as a percentage, as periodically
* updated by the unpacker.
* Values of 0 - 100 are normal, and -1 indicates a stall.
* Progress can be monitored by polling the value of this
* property.
* * At a minimum, the unpacker must set progress to 0 * at the beginning of a packing operation, and to 100 * at the end. */ String PROGRESS = "pack.progress"; /** The string "keep", a possible value for certain properties. * @see #DEFLATE_HINT * @see #MODIFICATION_TIME */ String KEEP = "keep"; /** The string "pass", a possible value for certain properties. * @see #UNKNOWN_ATTRIBUTE * @see #CLASS_ATTRIBUTE_PFX * @see #FIELD_ATTRIBUTE_PFX * @see #METHOD_ATTRIBUTE_PFX * @see #CODE_ATTRIBUTE_PFX */ String PASS = "pass"; /** The string "strip", a possible value for certain properties. * @see #UNKNOWN_ATTRIBUTE * @see #CLASS_ATTRIBUTE_PFX * @see #FIELD_ATTRIBUTE_PFX * @see #METHOD_ATTRIBUTE_PFX * @see #CODE_ATTRIBUTE_PFX */ String STRIP = "strip"; /** The string "error", a possible value for certain properties. * @see #UNKNOWN_ATTRIBUTE * @see #CLASS_ATTRIBUTE_PFX * @see #FIELD_ATTRIBUTE_PFX * @see #METHOD_ATTRIBUTE_PFX * @see #CODE_ATTRIBUTE_PFX */ String ERROR = "error"; /** The string "true", a possible value for certain properties. * @see #KEEP_FILE_ORDER * @see #DEFLATE_HINT */ String TRUE = "true"; /** The string "false", a possible value for certain properties. * @see #KEEP_FILE_ORDER * @see #DEFLATE_HINT */ String FALSE = "false"; /** The string "latest", a possible value for certain properties. * @see #MODIFICATION_TIME */ String LATEST = "latest"; /** * Get the set of this engine's properties. * This set is a "live view", so that changing its * contents immediately affects the Packer engine, and * changes from the engine (such as progress indications) * are immediately visible in the map. * *
The property map may contain pre-defined implementation * specific and default properties. Users are encouraged to * read the information and fully understand the implications, * before modifying pre-existing properties. *
* Implementation specific properties are prefixed with a * package name associated with the implementor, beginning * with com. or a similar prefix. * All property names beginning with pack. and * unpack. are reserved for use by this API. *
* Unknown properties may be ignored or rejected with an * unspecified error, and invalid entries may cause an * unspecified error to be thrown. * *
* The returned map implements all optional {@link SortedMap} operations
* @return A sorted association of property key strings to property
* values.
*/
SortedMap
* Closes its input but not its output. (Pack200 archives are appendable.)
* @param in a JarFile
* @param out an OutputStream
* @exception IOException if an error is encountered.
*/
void pack(JarFile in, OutputStream out) throws IOException ;
/**
* Takes a JarInputStream and converts it into a Pack200 archive.
*
* Closes its input but not its output. (Pack200 archives are appendable.)
*
* The modification time and deflation hint attributes are not available,
* for the JAR manifest file and its containing directory.
*
* @see #MODIFICATION_TIME
* @see #DEFLATE_HINT
* @param in a JarInputStream
* @param out an OutputStream
* @exception IOException if an error is encountered.
*/
void pack(JarInputStream in, OutputStream out) throws IOException ;
/**
* Registers a listener for PropertyChange events on the properties map.
* This is typically used by applications to update a progress bar.
*
* The default implementation of this method does nothing and has
* no side-effects. WARNING: This method is omitted from the interface
* declaration in all subset Profiles of Java SE that do not include
* the {@code java.beans} package. The default implementation of this method does nothing and has
* no side-effects. WARNING: This method is omitted from the interface
* declaration in all subset Profiles of Java SE that do not include
* the {@code java.beans} package.
* Every JAR file produced by this engine will include the string
* "PACK200" as a zip file comment.
* This allows a deployer to detect if a JAR archive was packed and unpacked.
*
* Note: Unless otherwise noted, passing a null argument to a
* constructor or method in this class will cause a {@link NullPointerException}
* to be thrown.
*
* This version of the unpacker is compatible with all previous versions.
* @since 1.5
*/
public interface Unpacker {
/** The string "keep", a possible value for certain properties.
* @see #DEFLATE_HINT
*/
String KEEP = "keep";
/** The string "true", a possible value for certain properties.
* @see #DEFLATE_HINT
*/
String TRUE = "true";
/** The string "false", a possible value for certain properties.
* @see #DEFLATE_HINT
*/
String FALSE = "false";
/**
* Property indicating that the unpacker should
* ignore all transmitted values for DEFLATE_HINT,
* replacing them by the given value, {@link #TRUE} or {@link #FALSE}.
* The default value is the special string {@link #KEEP},
* which asks the unpacker to preserve all transmitted
* deflation hints.
*/
String DEFLATE_HINT = "unpack.deflate.hint";
/**
* The unpacker's progress as a percentage, as periodically
* updated by the unpacker.
* Values of 0 - 100 are normal, and -1 indicates a stall.
* Progress can be monitored by polling the value of this
* property.
*
* At a minimum, the unpacker must set progress to 0
* at the beginning of a packing operation, and to 100
* at the end.
*/
String PROGRESS = "unpack.progress";
/**
* Get the set of this engine's properties. This set is
* a "live view", so that changing its
* contents immediately affects the Packer engine, and
* changes from the engine (such as progress indications)
* are immediately visible in the map.
*
* The property map may contain pre-defined implementation
* specific and default properties. Users are encouraged to
* read the information and fully understand the implications,
* before modifying pre-existing properties.
*
* Implementation specific properties are prefixed with a
* package name associated with the implementor, beginning
* with com. or a similar prefix.
* All property names beginning with pack. and
* unpack. are reserved for use by this API.
*
* Unknown properties may be ignored or rejected with an
* unspecified error, and invalid entries may cause an
* unspecified error to be thrown.
*
* @return A sorted association of option key strings to option values.
*/
SortedMap
* Closes its input but not its output. (The output can accumulate more elements.)
* @param in an InputStream.
* @param out a JarOutputStream.
* @exception IOException if an error is encountered.
*/
void unpack(InputStream in, JarOutputStream out) throws IOException;
/**
* Read a Pack200 archive, and write the encoded JAR to
* a JarOutputStream.
*
* Does not close its output. (The output can accumulate more elements.)
* @param in a File.
* @param out a JarOutputStream.
* @exception IOException if an error is encountered.
*/
void unpack(File in, JarOutputStream out) throws IOException;
/**
* Registers a listener for PropertyChange events on the properties map.
* This is typically used by applications to update a progress bar.
*
* The default implementation of this method does nothing and has
* no side-effects. WARNING: This method is omitted from the interface
* declaration in all subset Profiles of Java SE that do not include
* the {@code java.beans} package. The default implementation of this method does nothing and has
* no side-effects. WARNING: This method is omitted from the interface
* declaration in all subset Profiles of Java SE that do not include
* the {@code java.beans} package.