luni/src/main/java/java/io/InputStreamReader.java - platform/libcore-snapshot - Git at Google

 /*
  *  Licensed to the Apache Software Foundation (ASF) under one or more
  *  contributor license agreements.  See the NOTICE file distributed with
  *  this work for additional information regarding copyright ownership.
  *  The ASF licenses this file to You under the Apache License, Version 2.0
  *  (the "License"); you may not use this file except in compliance with
  *  the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  *  Unless required by applicable law or agreed to in writing, software
  *  distributed under the License is distributed on an "AS IS" BASIS,
  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  */

 package java.io;

 import java.nio.ByteBuffer;
 import java.nio.CharBuffer;
 import java.nio.charset.Charset;
 import java.nio.charset.CharsetDecoder;
 import java.nio.charset.CoderResult;
 import java.nio.charset.CodingErrorAction;
 import java.nio.charset.MalformedInputException;
 import java.nio.charset.UnmappableCharacterException;
 import java.util.Arrays;

 /**
  * A class for turning a byte stream into a character stream. Data read from the
  * source input stream is converted into characters by either a default or a
  * provided character converter. The default encoding is taken from the
  * "file.encoding" system property. {@code InputStreamReader} contains a buffer
  * of bytes read from the source stream and converts these into characters as
  * needed. The buffer size is 8K.
  *
  * @see OutputStreamWriter
  */
 public class InputStreamReader extends Reader {
     private InputStream in;

     private boolean endOfInput = false;

     private CharsetDecoder decoder;

     private final ByteBuffer bytes = ByteBuffer.allocate(8192);

     /**
      * Constructs a new {@code InputStreamReader} on the {@link InputStream}
      * {@code in}. This constructor sets the character converter to the encoding
      * specified in the "file.encoding" property and falls back to ISO 8859_1
      * (ISO-Latin-1) if the property doesn't exist.
      *
      * @param in
      *            the input stream from which to read characters.
      */
     public InputStreamReader(InputStream in) {
         this(in, Charset.defaultCharset());
     }

     /**
      * Constructs a new InputStreamReader on the InputStream {@code in}. The
      * character converter that is used to decode bytes into characters is
      * identified by name by {@code enc}. If the encoding cannot be found, an
      * UnsupportedEncodingException error is thrown.
      *
      * @param in
      *            the InputStream from which to read characters.
      * @param enc
      *            identifies the character converter to use.
      * @throws NullPointerException
      *             if {@code enc} is {@code null}.
      * @throws UnsupportedEncodingException
      *             if the encoding specified by {@code enc} cannot be found.
      */
     public InputStreamReader(InputStream in, final String enc)
             throws UnsupportedEncodingException {
         super(in);
         if (enc == null) {
             throw new NullPointerException();
         }
         this.in = in;
         try {
             decoder = Charset.forName(enc).newDecoder().onMalformedInput(
                     CodingErrorAction.REPLACE).onUnmappableCharacter(
                     CodingErrorAction.REPLACE);
         } catch (IllegalArgumentException e) {
             throw (UnsupportedEncodingException)
                     new UnsupportedEncodingException(enc).initCause(e);
         }
         bytes.limit(0);
     }

     /**
      * Constructs a new InputStreamReader on the InputStream {@code in} and
      * CharsetDecoder {@code dec}.
      *
      * @param in
      *            the source InputStream from which to read characters.
      * @param dec
      *            the CharsetDecoder used by the character conversion.
      */
     public InputStreamReader(InputStream in, CharsetDecoder dec) {
         super(in);
         dec.averageCharsPerByte();
         this.in = in;
         decoder = dec;
         bytes.limit(0);
     }

     /**
      * Constructs a new InputStreamReader on the InputStream {@code in} and
      * Charset {@code charset}.
      *
      * @param in
      *            the source InputStream from which to read characters.
      * @param charset
      *            the Charset that defines the character converter
      */
     public InputStreamReader(InputStream in, Charset charset) {
         super(in);
         this.in = in;
         decoder = charset.newDecoder().onMalformedInput(
                 CodingErrorAction.REPLACE).onUnmappableCharacter(
                 CodingErrorAction.REPLACE);
         bytes.limit(0);
     }

     /**
      * Closes this reader. This implementation closes the source InputStream and
      * releases all local storage.
      *
      * @throws IOException
      *             if an error occurs attempting to close this reader.
      */
     @Override
     public void close() throws IOException {
         synchronized (lock) {
             if (decoder != null) {
                 decoder.reset();
             }
             decoder = null;
             if (in != null) {
                 in.close();
                 in = null;
             }
         }
     }

     /**
      * Returns the historical name of the encoding used by this writer to convert characters to
      * bytes, or null if this writer has been closed. Most callers should probably keep
      * track of the String or Charset they passed in; this method may not return the same
      * name.
      */
     public String getEncoding() {
         if (!isOpen()) {
             return null;
         }
         return HistoricalCharsetNames.get(decoder.charset());
     }

     /**
      * Reads a single character from this reader and returns it as an integer
      * with the two higher-order bytes set to 0. Returns -1 if the end of the
      * reader has been reached. The byte value is either obtained from
      * converting bytes in this reader's buffer or by first filling the buffer
      * from the source InputStream and then reading from the buffer.
      *
      * @return the character read or -1 if the end of the reader has been
      *         reached.
      * @throws IOException
      *             if this reader is closed or some other I/O error occurs.
      */
     @Override
     public int read() throws IOException {
         synchronized (lock) {
             if (!isOpen()) {
                 throw new IOException("InputStreamReader is closed");
             }
             char[] buf = new char[1];
             return read(buf, 0, 1) != -1 ? buf[0] : -1;
         }
     }

     /**
      * Reads at most {@code length} characters from this reader and stores them
      * at position {@code offset} in the character array {@code buf}. Returns
      * the number of characters actually read or -1 if the end of the reader has
      * been reached. The bytes are either obtained from converting bytes in this
      * reader's buffer or by first filling the buffer from the source
      * InputStream and then reading from the buffer.
      *
      * @param buffer
      *            the array to store the characters read.
      * @param offset
      *            the initial position in {@code buf} to store the characters
      *            read from this reader.
      * @param length
      *            the maximum number of characters to read.
      * @return the number of characters read or -1 if the end of the reader has
      *         been reached.
      * @throws IndexOutOfBoundsException
      *             if {@code offset < 0} or {@code length < 0}, or if
      *             {@code offset + length} is greater than the length of
      *             {@code buf}.
      * @throws IOException
      *             if this reader is closed or some other I/O error occurs.
      */
     @Override
     public int read(char[] buffer, int offset, int length) throws IOException {
         synchronized (lock) {
             if (!isOpen()) {
                 throw new IOException("InputStreamReader is closed");
             }

             Arrays.checkOffsetAndCount(buffer.length, offset, length);
             if (length == 0) {
                 return 0;
             }

             CharBuffer out = CharBuffer.wrap(buffer, offset, length);
             CoderResult result = CoderResult.UNDERFLOW;

             // bytes.remaining() indicates number of bytes in buffer
             // when 1-st time entered, it'll be equal to zero
             boolean needInput = !bytes.hasRemaining();

             while (out.hasRemaining()) {
                 // fill the buffer if needed
                 if (needInput) {
                     try {
                         if (in.available() == 0 && out.position() > offset) {
                             // we could return the result without blocking read
                             break;
                         }
                     } catch (IOException e) {
                         // available didn't work so just try the read
                     }

                     int desiredByteCount = bytes.capacity() - bytes.limit();
                     int off = bytes.arrayOffset() + bytes.limit();
                     int actualByteCount = in.read(bytes.array(), off, desiredByteCount);

                     if (actualByteCount == -1) {
                         endOfInput = true;
                         break;
                     } else if (actualByteCount == 0) {
                         break;
                     }
                     bytes.limit(bytes.limit() + actualByteCount);
                     needInput = false;
                 }

                 // decode bytes
                 result = decoder.decode(bytes, out, false);

                 if (result.isUnderflow()) {
                     // compact the buffer if no space left
                     if (bytes.limit() == bytes.capacity()) {
                         bytes.compact();
                         bytes.limit(bytes.position());
                         bytes.position(0);
                     }
                     needInput = true;
                 } else {
                     break;
                 }
             }

             if (result == CoderResult.UNDERFLOW && endOfInput) {
                 result = decoder.decode(bytes, out, true);
                 decoder.flush(out);
                 decoder.reset();
             }
             if (result.isMalformed() || result.isUnmappable()) {
                 result.throwException();
             }

             return out.position() - offset == 0 ? -1 : out.position() - offset;
         }
     }

     private boolean isOpen() {
         return in != null;
     }

     /**
      * Indicates whether this reader is ready to be read without blocking. If
      * the result is {@code true}, the next {@code read()} will not block. If
      * the result is {@code false} then this reader may or may not block when
      * {@code read()} is called. This implementation returns {@code true} if
      * there are bytes available in the buffer or the source stream has bytes
      * available.
      *
      * @return {@code true} if the receiver will not block when {@code read()}
      *         is called, {@code false} if unknown or blocking will occur.
      * @throws IOException
      *             if this reader is closed or some other I/O error occurs.
      */
     @Override
     public boolean ready() throws IOException {
         synchronized (lock) {
             if (in == null) {
                 throw new IOException("InputStreamReader is closed");
             }
             try {
                 return bytes.hasRemaining() || in.available() > 0;
             } catch (IOException e) {
                 return false;
             }
         }
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package java.io;

	import java.nio.ByteBuffer;
	import java.nio.CharBuffer;
	import java.nio.charset.Charset;
	import java.nio.charset.CharsetDecoder;
	import java.nio.charset.CoderResult;
	import java.nio.charset.CodingErrorAction;
	import java.nio.charset.MalformedInputException;
	import java.nio.charset.UnmappableCharacterException;
	import java.util.Arrays;

	/**
	* A class for turning a byte stream into a character stream. Data read from the
	* source input stream is converted into characters by either a default or a
	* provided character converter. The default encoding is taken from the
	* "file.encoding" system property. {@code InputStreamReader} contains a buffer
	* of bytes read from the source stream and converts these into characters as
	* needed. The buffer size is 8K.
	*
	* @see OutputStreamWriter
	*/
	public class InputStreamReader extends Reader {
	private InputStream in;

	private boolean endOfInput = false;

	private CharsetDecoder decoder;

	private final ByteBuffer bytes = ByteBuffer.allocate(8192);

	/**
	* Constructs a new {@code InputStreamReader} on the {@link InputStream}
	* {@code in}. This constructor sets the character converter to the encoding
	* specified in the "file.encoding" property and falls back to ISO 8859_1
	* (ISO-Latin-1) if the property doesn't exist.
	*
	* @param in
	* the input stream from which to read characters.
	*/
	public InputStreamReader(InputStream in) {
	this(in, Charset.defaultCharset());
	}

	/**
	* Constructs a new InputStreamReader on the InputStream {@code in}. The
	* character converter that is used to decode bytes into characters is
	* identified by name by {@code enc}. If the encoding cannot be found, an
	* UnsupportedEncodingException error is thrown.
	*
	* @param in
	* the InputStream from which to read characters.
	* @param enc
	* identifies the character converter to use.
	* @throws NullPointerException
	* if {@code enc} is {@code null}.
	* @throws UnsupportedEncodingException
	* if the encoding specified by {@code enc} cannot be found.
	*/
	public InputStreamReader(InputStream in, final String enc)
	throws UnsupportedEncodingException {
	super(in);
	if (enc == null) {
	throw new NullPointerException();
	}
	this.in = in;
	try {
	decoder = Charset.forName(enc).newDecoder().onMalformedInput(
	CodingErrorAction.REPLACE).onUnmappableCharacter(
	CodingErrorAction.REPLACE);
	} catch (IllegalArgumentException e) {
	throw (UnsupportedEncodingException)
	new UnsupportedEncodingException(enc).initCause(e);
	}
	bytes.limit(0);
	}

	/**
	* Constructs a new InputStreamReader on the InputStream {@code in} and
	* CharsetDecoder {@code dec}.
	*
	* @param in
	* the source InputStream from which to read characters.
	* @param dec
	* the CharsetDecoder used by the character conversion.
	*/
	public InputStreamReader(InputStream in, CharsetDecoder dec) {
	super(in);
	dec.averageCharsPerByte();
	this.in = in;
	decoder = dec;
	bytes.limit(0);
	}

	/**
	* Constructs a new InputStreamReader on the InputStream {@code in} and
	* Charset {@code charset}.
	*
	* @param in
	* the source InputStream from which to read characters.
	* @param charset
	* the Charset that defines the character converter
	*/
	public InputStreamReader(InputStream in, Charset charset) {
	super(in);
	this.in = in;
	decoder = charset.newDecoder().onMalformedInput(
	CodingErrorAction.REPLACE).onUnmappableCharacter(
	CodingErrorAction.REPLACE);
	bytes.limit(0);
	}

	/**
	* Closes this reader. This implementation closes the source InputStream and
	* releases all local storage.
	*
	* @throws IOException
	* if an error occurs attempting to close this reader.
	*/
	@Override
	public void close() throws IOException {
	synchronized (lock) {
	if (decoder != null) {
	decoder.reset();
	}
	decoder = null;
	if (in != null) {
	in.close();
	in = null;
	}
	}
	}

	/**
	* Returns the historical name of the encoding used by this writer to convert characters to
	* bytes, or null if this writer has been closed. Most callers should probably keep
	* track of the String or Charset they passed in; this method may not return the same
	* name.
	*/
	public String getEncoding() {
	if (!isOpen()) {
	return null;
	}
	return HistoricalCharsetNames.get(decoder.charset());
	}

	/**
	* Reads a single character from this reader and returns it as an integer
	* with the two higher-order bytes set to 0. Returns -1 if the end of the
	* reader has been reached. The byte value is either obtained from
	* converting bytes in this reader's buffer or by first filling the buffer
	* from the source InputStream and then reading from the buffer.
	*
	* @return the character read or -1 if the end of the reader has been
	* reached.
	* @throws IOException
	* if this reader is closed or some other I/O error occurs.
	*/
	@Override
	public int read() throws IOException {
	synchronized (lock) {
	if (!isOpen()) {
	throw new IOException("InputStreamReader is closed");
	}
	char[] buf = new char[1];
	return read(buf, 0, 1) != -1 ? buf[0] : -1;
	}
	}

	/**
	* Reads at most {@code length} characters from this reader and stores them
	* at position {@code offset} in the character array {@code buf}. Returns
	* the number of characters actually read or -1 if the end of the reader has
	* been reached. The bytes are either obtained from converting bytes in this
	* reader's buffer or by first filling the buffer from the source
	* InputStream and then reading from the buffer.
	*
	* @param buffer
	* the array to store the characters read.
	* @param offset
	* the initial position in {@code buf} to store the characters
	* read from this reader.
	* @param length
	* the maximum number of characters to read.
	* @return the number of characters read or -1 if the end of the reader has
	* been reached.
	* @throws IndexOutOfBoundsException
	* if {@code offset < 0} or {@code length < 0}, or if
	* {@code offset + length} is greater than the length of
	* {@code buf}.
	* @throws IOException
	* if this reader is closed or some other I/O error occurs.
	*/
	@Override
	public int read(char[] buffer, int offset, int length) throws IOException {
	synchronized (lock) {
	if (!isOpen()) {
	throw new IOException("InputStreamReader is closed");
	}

	Arrays.checkOffsetAndCount(buffer.length, offset, length);
	if (length == 0) {
	return 0;
	}

	CharBuffer out = CharBuffer.wrap(buffer, offset, length);
	CoderResult result = CoderResult.UNDERFLOW;

	// bytes.remaining() indicates number of bytes in buffer
	// when 1-st time entered, it'll be equal to zero
	boolean needInput = !bytes.hasRemaining();

	while (out.hasRemaining()) {
	// fill the buffer if needed
	if (needInput) {
	try {
	if (in.available() == 0 && out.position() > offset) {
	// we could return the result without blocking read
	break;
	}
	} catch (IOException e) {
	// available didn't work so just try the read
	}

	int desiredByteCount = bytes.capacity() - bytes.limit();
	int off = bytes.arrayOffset() + bytes.limit();
	int actualByteCount = in.read(bytes.array(), off, desiredByteCount);

	if (actualByteCount == -1) {
	endOfInput = true;
	break;
	} else if (actualByteCount == 0) {
	break;
	}
	bytes.limit(bytes.limit() + actualByteCount);
	needInput = false;
	}

	// decode bytes
	result = decoder.decode(bytes, out, false);

	if (result.isUnderflow()) {
	// compact the buffer if no space left
	if (bytes.limit() == bytes.capacity()) {
	bytes.compact();
	bytes.limit(bytes.position());
	bytes.position(0);
	}
	needInput = true;
	} else {
	break;
	}
	}

	if (result == CoderResult.UNDERFLOW && endOfInput) {
	result = decoder.decode(bytes, out, true);
	decoder.flush(out);
	decoder.reset();
	}
	if (result.isMalformed() \|\| result.isUnmappable()) {
	result.throwException();
	}

	return out.position() - offset == 0 ? -1 : out.position() - offset;
	}
	}

	private boolean isOpen() {
	return in != null;
	}

	/**
	* Indicates whether this reader is ready to be read without blocking. If
	* the result is {@code true}, the next {@code read()} will not block. If
	* the result is {@code false} then this reader may or may not block when
	* {@code read()} is called. This implementation returns {@code true} if
	* there are bytes available in the buffer or the source stream has bytes
	* available.
	*
	* @return {@code true} if the receiver will not block when {@code read()}
	* is called, {@code false} if unknown or blocking will occur.
	* @throws IOException
	* if this reader is closed or some other I/O error occurs.
	*/
	@Override
	public boolean ready() throws IOException {
	synchronized (lock) {
	if (in == null) {
	throw new IOException("InputStreamReader is closed");
	}
	try {
	return bytes.hasRemaining() \|\| in.available() > 0;
	} catch (IOException e) {
	return false;
	}
	}
	}
	}