charset}. The charset that it uses
* may be specified by name or may be given explicitly, or the platform's
* default charset may be accepted.
*
* Each invocation of one of an InputStreamReader's read() methods may * cause one or more bytes to be read from the underlying byte-input stream. * To enable the efficient conversion of bytes to characters, more bytes may * be read ahead from the underlying stream than are necessary to satisfy the * current read operation. * *
For top efficiency, consider wrapping an InputStreamReader within a * BufferedReader. For example: * *
* BufferedReader in * = new BufferedReader(new InputStreamReader(System.in)); ** * @see BufferedReader * @see InputStream * @see java.nio.charset.Charset * * @author Mark Reinhold * @since JDK1.1 */ public class InputStreamReader extends Reader { private final StreamDecoder sd; /** * Creates an InputStreamReader that uses the default charset. * * @param in An InputStream */ public InputStreamReader(InputStream in) { super(in); try { sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## check lock object } catch (UnsupportedEncodingException e) { // The default encoding should always be available throw new Error(e); } } /** * Creates an InputStreamReader that uses the named charset. * * @param in * An InputStream * * @param charsetName * The name of a supported * {@link java.nio.charset.Charset charset
}
*
* @exception UnsupportedEncodingException
* If the named charset is not supported
*/
public InputStreamReader(InputStream in, String charsetName)
throws UnsupportedEncodingException
{
super(in);
if (charsetName == null)
throw new NullPointerException("charsetName");
sd = StreamDecoder.forInputStreamReader(in, this, charsetName);
}
/**
* Creates an InputStreamReader that uses the given charset.
*
* @param in An InputStream
* @param cs A charset
*
* @since 1.4
* @spec JSR-51
*/
public InputStreamReader(InputStream in, Charset cs) {
super(in);
if (cs == null)
throw new NullPointerException("charset");
sd = StreamDecoder.forInputStreamReader(in, this, cs);
}
/**
* Creates an InputStreamReader that uses the given charset decoder.
*
* @param in An InputStream
* @param dec A charset decoder
*
* @since 1.4
* @spec JSR-51
*/
public InputStreamReader(InputStream in, CharsetDecoder dec) {
super(in);
if (dec == null)
throw new NullPointerException("charset decoder");
sd = StreamDecoder.forInputStreamReader(in, this, dec);
}
/**
* Returns the name of the character encoding being used by this stream.
*
* If the encoding has an historical name then that name is returned;
* otherwise the encoding's canonical name is returned.
*
*
If this instance was created with the {@link
* #InputStreamReader(InputStream, String)} constructor then the returned
* name, being unique for the encoding, may differ from the name passed to
* the constructor. This method will return null if the
* stream has been closed.
*
* @return The historical name of this encoding, or
* null if the stream has been closed
*
* @see java.nio.charset.Charset
*
* @revised 1.4
* @spec JSR-51
*/
public String getEncoding() {
return sd.getEncoding();
}
/**
* Reads a single character.
*
* @return The character read, or -1 if the end of the stream has been
* reached
*
* @exception IOException If an I/O error occurs
*/
public int read() throws IOException {
return sd.read();
}
/**
* Reads characters into a portion of an array.
*
* @param cbuf Destination buffer
* @param offset Offset at which to start storing characters
* @param length Maximum number of characters to read
*
* @return The number of characters read, or -1 if the end of the
* stream has been reached
*
* @exception IOException If an I/O error occurs
*/
public int read(char cbuf[], int offset, int length) throws IOException {
return sd.read(cbuf, offset, length);
}
/**
* Tells whether this stream is ready to be read. An InputStreamReader is
* ready if its input buffer is not empty, or if bytes are available to be
* read from the underlying byte stream.
*
* @exception IOException If an I/O error occurs
*/
public boolean ready() throws IOException {
return sd.ready();
}
public void close() throws IOException {
sd.close();
}
}