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 { // /** // * 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); // } // } private InputStream in; private boolean isOpen = true; private String charsetName; private boolean isUTF8; /** * 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);
this.in = in;
this.charsetName = charsetName;
if (!(isUTF8 = "UTF-8".equals(charsetName)) && !"ISO-8859-1".equals(charsetName))
throw new NullPointerException("charsetName");
//in.resetStream();
//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 this.charsetName;
//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();
// }
private byte[] bytearr = null;
private int pos;
/**
* Reads characters into a portion of an array. Adapted by Bob Hanson to be
* more flexible, allowing char codes 128-255 as simple characters and avoid
* the use of string decoders. Will gracefully turn off isUTF if rules are not
* followed.
*
* @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
*/
@Override
public int read(char cbuf[], int offset, int length) throws IOException {
// borrowed from DataInputStream:
if (bytearr == null || bytearr.length < length)
bytearr = new byte[length];
int c, char2, char3;
int byteCount = 0;
int charCount = offset;
int byteLen = in.read(bytearr, pos, length - pos);
int nAvail = in.available();
if (byteLen < 0)
return -1;
int nMax = byteLen;
while (byteCount < nMax) {
c = bytearr[byteCount] & 0xff;
if (isUTF8)
switch (c >> 4) {
case 0xC:
case 0xD:
/* 110x xxxx 10xx xxxx*/
if (byteCount + 1 >= byteLen) {
if (nAvail >= 1) {
// truncate at this point and
// check in the next round
nMax = byteCount;
continue;
}
} else if (((char2 = bytearr[byteCount + 1]) & 0xC0) == 0x80) {
cbuf[charCount++] = (char) (((c & 0x1F) << 6) | (char2 & 0x3F));
byteCount += 2;
continue;
}
isUTF8 = false;
break;
case 0xE:
/* 1110 xxxx 10xx xxxx 10xx xxxx */
if (byteCount + 2 >= byteLen) {
if (nAvail >= 2) {
// truncate at this point and
// check in the next round
nMax = byteCount;
continue;
}
} else if (((char2 = bytearr[byteCount + 1]) & 0xC0) == 0x80
&& ((char3 = bytearr[byteCount + 2]) & 0xC0) == 0x80) {
cbuf[charCount++] = (char) (((c & 0x0F) << 12)
| ((char2 & 0x3F) << 6) | (char3 & 0x3F));
byteCount += 3;
continue;
}
isUTF8 = false;
break;
}
/* 0xxxxxxx or otherwise unreadable -- just take it to be a character and don't worry about it.*/
byteCount++;
cbuf[charCount++] = (char) c;
}
// The number of chars produced may be less than utflen
pos = byteLen - byteCount;
for (int i = 0; i < pos; i++) {
bytearr[i] = bytearr[byteCount++];
}
return charCount - offset;
}
/**
* 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
*/
@Override
public boolean ready() throws IOException {
return isOpen;
}
@Override
public void close() throws IOException {
in.close();
isOpen = false;
}
}