charset}. The charset that it uses
jaroslav@557: * may be specified by name or may be given explicitly, or the platform's
jaroslav@557: * default charset may be accepted.
jaroslav@557: *
jaroslav@557: * Each invocation of one of an InputStreamReader's read() methods may jaroslav@557: * cause one or more bytes to be read from the underlying byte-input stream. jaroslav@557: * To enable the efficient conversion of bytes to characters, more bytes may jaroslav@557: * be read ahead from the underlying stream than are necessary to satisfy the jaroslav@557: * current read operation. jaroslav@557: * jaroslav@557: *
For top efficiency, consider wrapping an InputStreamReader within a jaroslav@557: * BufferedReader. For example: jaroslav@557: * jaroslav@557: *
jaroslav@557: * BufferedReader in jaroslav@557: * = new BufferedReader(new InputStreamReader(System.in)); jaroslav@557: *jaroslav@557: * jaroslav@557: * @see BufferedReader jaroslav@557: * @see InputStream jaroslav@557: * @see java.nio.charset.Charset jaroslav@557: * jaroslav@557: * @author Mark Reinhold jaroslav@557: * @since JDK1.1 jaroslav@557: */ jaroslav@557: jaroslav@557: public class InputStreamReader extends Reader { jaroslav@557: jaroslav@557: /** jaroslav@557: * Creates an InputStreamReader that uses the default charset. jaroslav@557: * jaroslav@557: * @param in An InputStream jaroslav@557: */ jaroslav@557: public InputStreamReader(InputStream in) { jaroslav@557: super(in); jaroslav@557: } jaroslav@557: jaroslav@557: /** jaroslav@557: * Creates an InputStreamReader that uses the named charset. jaroslav@557: * jaroslav@557: * @param in jaroslav@557: * An InputStream jaroslav@557: * jaroslav@557: * @param charsetName jaroslav@557: * The name of a supported jaroslav@557: * {@link java.nio.charset.Charset charset
}
jaroslav@557: *
jaroslav@557: * @exception UnsupportedEncodingException
jaroslav@557: * If the named charset is not supported
jaroslav@557: */
jaroslav@557: public InputStreamReader(InputStream in, String charsetName)
jaroslav@557: throws UnsupportedEncodingException
jaroslav@557: {
jaroslav@557: super(in);
jaroslav@561: if (!charsetName.toUpperCase().equals("UTF-8")) {
jaroslav@561: throw new UnsupportedEncodingException(charsetName);
jaroslav@561: }
jaroslav@557: }
jaroslav@557:
jaroslav@557: /**
jaroslav@557: * Creates an InputStreamReader that uses the given charset.
jaroslav@557: *
jaroslav@557: * @param in An InputStream
jaroslav@557: * @param cs A charset
jaroslav@557: *
jaroslav@557: * @since 1.4
jaroslav@557: * @spec JSR-51
jaroslav@557: */
jaroslav@560: /* XXX:
jaroslav@557: public InputStreamReader(InputStream in, Charset cs) {
jaroslav@557: super(in);
jaroslav@557: if (cs == null)
jaroslav@557: throw new NullPointerException("charset");
jaroslav@557: sd = StreamDecoder.forInputStreamReader(in, this, cs);
jaroslav@557: }
jaroslav@560: */
jaroslav@557: /**
jaroslav@557: * Creates an InputStreamReader that uses the given charset decoder.
jaroslav@557: *
jaroslav@557: * @param in An InputStream
jaroslav@557: * @param dec A charset decoder
jaroslav@557: *
jaroslav@557: * @since 1.4
jaroslav@557: * @spec JSR-51
jaroslav@557: */
jaroslav@560: /* XXX:
jaroslav@557: public InputStreamReader(InputStream in, CharsetDecoder dec) {
jaroslav@557: super(in);
jaroslav@557: if (dec == null)
jaroslav@557: throw new NullPointerException("charset decoder");
jaroslav@557: sd = StreamDecoder.forInputStreamReader(in, this, dec);
jaroslav@557: }
jaroslav@560: */
jaroslav@560:
jaroslav@557: /**
jaroslav@557: * Returns the name of the character encoding being used by this stream.
jaroslav@557: *
jaroslav@557: * If the encoding has an historical name then that name is returned;
jaroslav@557: * otherwise the encoding's canonical name is returned.
jaroslav@557: *
jaroslav@557: *
If this instance was created with the {@link
jaroslav@557: * #InputStreamReader(InputStream, String)} constructor then the returned
jaroslav@557: * name, being unique for the encoding, may differ from the name passed to
jaroslav@557: * the constructor. This method will return null if the
jaroslav@557: * stream has been closed.
jaroslav@557: *
jaroslav@557: * @return The historical name of this encoding, or
jaroslav@557: * null if the stream has been closed
jaroslav@557: *
jaroslav@557: * @see java.nio.charset.Charset
jaroslav@557: *
jaroslav@557: * @revised 1.4
jaroslav@557: * @spec JSR-51
jaroslav@557: */
jaroslav@557: public String getEncoding() {
jaroslav@561: return "UTF-8";
jaroslav@557: }
jaroslav@557:
jaroslav@557: /**
jaroslav@557: * Reads a single character.
jaroslav@557: *
jaroslav@557: * @return The character read, or -1 if the end of the stream has been
jaroslav@557: * reached
jaroslav@557: *
jaroslav@557: * @exception IOException If an I/O error occurs
jaroslav@557: */
jaroslav@557: public int read() throws IOException {
jaroslav@595: final InputStream is = (InputStream)lock;
jaroslav@595: int c = is.read();
jaroslav@595: if (c == -1) {
jaroslav@595: return -1;
jaroslav@595: }
jaroslav@595: c = (int) c & 0xff;
jaroslav@595: switch (c >> 4) {
jaroslav@595: case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
jaroslav@595: /* 0xxxxxxx*/
jaroslav@595: return c;
jaroslav@595: case 12: case 13: {
jaroslav@595: /* 110x xxxx 10xx xxxx*/
jaroslav@595: int char2 = (int) is.read();
jaroslav@595: if ((char2 & 0xC0) != 0x80)
jaroslav@595: throw new UTFDataFormatException("malformed input");
jaroslav@595: return (((c & 0x1F) << 6) | (char2 & 0x3F));
jaroslav@595: }
jaroslav@595: case 14: {
jaroslav@595: /* 1110 xxxx 10xx xxxx 10xx xxxx */
jaroslav@595: int char2 = is.read();
jaroslav@595: int char3 = is.read();
jaroslav@595: if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80))
jaroslav@595: throw new UTFDataFormatException("malformed input");
jaroslav@595: return (((c & 0x0F) << 12) |
jaroslav@595: ((char2 & 0x3F) << 6) |
jaroslav@595: ((char3 & 0x3F) << 0));
jaroslav@595: }
jaroslav@595: default:
jaroslav@595: /* 10xx xxxx, 1111 xxxx */
jaroslav@595: throw new UTFDataFormatException("malformed input");
jaroslav@595: }
jaroslav@557: }
jaroslav@595:
jaroslav@557: /**
jaroslav@557: * Reads characters into a portion of an array.
jaroslav@557: *
jaroslav@557: * @param cbuf Destination buffer
jaroslav@557: * @param offset Offset at which to start storing characters
jaroslav@557: * @param length Maximum number of characters to read
jaroslav@557: *
jaroslav@557: * @return The number of characters read, or -1 if the end of the
jaroslav@557: * stream has been reached
jaroslav@557: *
jaroslav@557: * @exception IOException If an I/O error occurs
jaroslav@557: */
jaroslav@557: public int read(char cbuf[], int offset, int length) throws IOException {
jaroslav@561: for (int i = 0; i < length; i++) {
jaroslav@561: int ch = read();
jaroslav@561: if (ch == -1) {
jaroslav@561: if (i == 0) return -1;
jaroslav@561: return i;
jaroslav@561: }
jaroslav@561: cbuf[offset++] = (char) ch;
jaroslav@561: }
jaroslav@561: return length;
jaroslav@557: }
jaroslav@557:
jaroslav@557: /**
jaroslav@557: * Tells whether this stream is ready to be read. An InputStreamReader is
jaroslav@557: * ready if its input buffer is not empty, or if bytes are available to be
jaroslav@557: * read from the underlying byte stream.
jaroslav@557: *
jaroslav@557: * @exception IOException If an I/O error occurs
jaroslav@557: */
jaroslav@557: public boolean ready() throws IOException {
jaroslav@561: return ((InputStream)lock).available() > 0;
jaroslav@557: }
jaroslav@557:
jaroslav@557: public void close() throws IOException {
jaroslav@561: ((InputStream)lock).close();
jaroslav@557: }
jaroslav@557: }