dataoutputstream.java

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/*
 * @(#)DataOutputStream.java	1.40 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package java.io;

/**
 * A data output stream lets an application write primitive Java data 
 * types to an output stream in a portable way. An application can 
 * then use a data input stream to read the data back in. 
 *
 * @author  unascribed
 * @version 1.34 10/17/00
 * @see     java.io.DataInputStream
 * @since   JDK1.0
 */
public
class DataOutputStream extends FilterOutputStream implements DataOutput {
    /**
     * The number of bytes written to the data output stream so far. 
     * If this counter overflows, it will be wrapped to Integer.MAX_VALUE.
     */
    protected int written;

    /**
     * Creates a new data output stream to write data to the specified 
     * underlying output stream. The counter <code>written</code> is 
     * set to zero.
     *
     * @param   out   the underlying output stream, to be saved for later 
     *                use.
     * @see     java.io.FilterOutputStream#out
     */
    public DataOutputStream(OutputStream out) {
	super(out);
    }

    /**
     * Increases the written counter by the specified value
     * until it reaches Integer.MAX_VALUE.
     */
    private void incCount(int value) {
        int temp = written + value;
        if (temp < 0) {
            temp = Integer.MAX_VALUE;
        }
        written = temp;
    }

    /**
     * Writes the specified byte (the low eight bits of the argument 
     * <code>b</code>) to the underlying output stream. If no exception 
     * is thrown, the counter <code>written</code> is incremented by 
     * <code>1</code>.
     * <p>
     * Implements the <code>write</code> method of <code>OutputStream</code>.
     *
     * @param      b   the <code>byte</code> to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public synchronized void write(int b) throws IOException {
	out.write(b);
        incCount(1);
    }

    /**
     * Writes <code>len</code> bytes from the specified byte array 
     * starting at offset <code>off</code> to the underlying output stream. 
     * If no exception is thrown, the counter <code>written</code> is 
     * incremented by <code>len</code>.
     *
     * @param      b     the data.
     * @param      off   the start offset in the data.
     * @param      len   the number of bytes to write.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public synchronized void write(byte b[], int off, int len)
	throws IOException
    {
	out.write(b, off, len);
	incCount(len);
    }

    /**
     * Flushes this data output stream. This forces any buffered output 
     * bytes to be written out to the stream. 
     * <p>
     * The <code>flush</code> method of <code>DataOuputStream</code> 
     * calls the <code>flush</code> method of its underlying output stream.
     *
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     * @see        java.io.OutputStream#flush()
     */
    public void flush() throws IOException {
	out.flush();
    }

    /**
     * Writes a <code>boolean</code> to the underlying output stream as 
     * a 1-byte value. The value <code>true</code> is written out as the 
     * value <code>(byte)1</code>; the value <code>false</code> is 
     * written out as the value <code>(byte)0</code>. If no exception is 
     * thrown, the counter <code>written</code> is incremented by 
     * <code>1</code>.
     *
     * @param      v   a <code>boolean</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public final void writeBoolean(boolean v) throws IOException {
	out.write(v ? 1 : 0);
	incCount(1);
    }

    /**
     * Writes out a <code>byte</code> to the underlying output stream as 
     * a 1-byte value. If no exception is thrown, the counter 
     * <code>written</code> is incremented by <code>1</code>.
     *
     * @param      v   a <code>byte</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public final void writeByte(int v) throws IOException {
	out.write(v);
        incCount(1);
    }

    /**
     * Writes a <code>short</code> to the underlying output stream as two
     * bytes, high byte first. If no exception is thrown, the counter 
     * <code>written</code> is incremented by <code>2</code>.
     *
     * @param      v   a <code>short</code> to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public final void writeShort(int v) throws IOException {
        out.write((v >>> 8) & 0xFF);
        out.write((v >>> 0) & 0xFF);
        incCount(2);
    }

    /**
     * Writes a <code>char</code> to the underlying output stream as a 
     * 2-byte value, high byte first. If no exception is thrown, the 
     * counter <code>written</code> is incremented by <code>2</code>.
     *
     * @param      v   a <code>char</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public final void writeChar(int v) throws IOException {
        out.write((v >>> 8) & 0xFF);
        out.write((v >>> 0) & 0xFF);
        incCount(2);
    }

    /**
     * Writes an <code>int</code> to the underlying output stream as four
     * bytes, high byte first. If no exception is thrown, the counter 
     * <code>written</code> is incremented by <code>4</code>.
     *
     * @param      v   an <code>int</code> to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public final void writeInt(int v) throws IOException {
        out.write((v >>> 24) & 0xFF);
        out.write((v >>> 16) & 0xFF);
        out.write((v >>>  8) & 0xFF);
        out.write((v >>>  0) & 0xFF);
        incCount(4);
    }

    private byte writeBuffer[] = new byte[8];

    /**
     * Writes a <code>long</code> to the underlying output stream as eight
     * bytes, high byte first. In no exception is thrown, the counter 
     * <code>written</code> is incremented by <code>8</code>.
     *
     * @param      v   a <code>long</code> to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public final void writeLong(long v) throws IOException {
        writeBuffer[0] = (byte)(v >>> 56);
        writeBuffer[1] = (byte)(v >>> 48);
        writeBuffer[2] = (byte)(v >>> 40);
        writeBuffer[3] = (byte)(v >>> 32);
        writeBuffer[4] = (byte)(v >>> 24);
        writeBuffer[5] = (byte)(v >>> 16);
        writeBuffer[6] = (byte)(v >>>  8);
        writeBuffer[7] = (byte)(v >>>  0);
        out.write(writeBuffer, 0, 8);
	incCount(8);
    }

    /**
     * Converts the float argument to an <code>int</code> using the 
     * <code>floatToIntBits</code> method in class <code>Float</code>, 
     * and then writes that <code>int</code> value to the underlying 
     * output stream as a 4-byte quantity, high byte first. If no 
     * exception is thrown, the counter <code>written</code> is 
     * incremented by <code>4</code>.
     *
     * @param      v   a <code>float</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     * @see        java.lang.Float#floatToIntBits(float)
     */
    public final void writeFloat(float v) throws IOException {
	writeInt(Float.floatToIntBits(v));
    }

    /**
     * Converts the double argument to a <code>long</code> using the 
     * <code>doubleToLongBits</code> method in class <code>Double</code>, 
     * and then writes that <code>long</code> value to the underlying 
     * output stream as an 8-byte quantity, high byte first. If no 
     * exception is thrown, the counter <code>written</code> is 
     * incremented by <code>8</code>.
     *
     * @param      v   a <code>double</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     * @see        java.lang.Double#doubleToLongBits(double)
     */
    public final void writeDouble(double v) throws IOException {
	writeLong(Double.doubleToLongBits(v));
    }

    /**
     * Writes out the string to the underlying output stream as a 
     * sequence of bytes. Each character in the string is written out, in 
     * sequence, by discarding its high eight bits. If no exception is 
     * thrown, the counter <code>written</code> is incremented by the 
     * length of <code>s</code>.
     *
     * @param      s   a string of bytes to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterOutputStream#out
     */
    public final void writeBytes(String s) throws IOException {
	int len = s.length();
	for (int i = 0 ; i < len ; i++) {
	    out.write((byte)s.charAt(i));
	}
	incCount(len);
    }

    /**
     * Writes a string to the underlying output stream as a sequence of 
     * characters. Each character is written to the data output stream as 
     * if by the <code>writeChar</code> method. If no exception is 
     * thrown, the counter <code>written</code> is incremented by twice 
     * the length of <code>s</code>.
     *
     * @param      s   a <code>String</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.DataOutputStream#writeChar(int)
     * @see        java.io.FilterOutputStream#out
     */
    public final void writeChars(String s) throws IOException {
        int len = s.length();
        for (int i = 0 ; i < len ; i++) {
            int v = s.charAt(i);
            out.write((v >>> 8) & 0xFF); 
            out.write((v >>> 0) & 0xFF); 
        }
        incCount(len * 2);
    }

    /**
     * Writes a string to the underlying output stream using Java modified
     * UTF-8 encoding in a machine-independent manner. 
     * <p>
     * First, two bytes are written to the output stream as if by the 
     * <code>writeShort</code> method giving the number of bytes to 
     * follow. This value is the number of bytes actually written out, 
     * not the length of the string. Following the length, each character 
     * of the string is output, in sequence, using the modified UTF-8 encoding
     * for the character. If no exception is thrown, the counter 
     * <code>written</code> is incremented by the total number of 
     * bytes written to the output stream. This will be at least two 
     * plus the length of <code>str</code>, and at most two plus 
     * thrice the length of <code>str</code>.
     *
     * @param      str   a string to be written.
     * @exception  IOException  if an I/O error occurs.
     */
    public final void writeUTF(String str) throws IOException {
        writeUTF(str, this);
    }

    /**
     * Writes a string to the specified DataOutput using Java modified UTF-8
     * encoding in a machine-independent manner. 
     * <p>
     * First, two bytes are written to out as if by the <code>writeShort</code>
     * method giving the number of bytes to follow. This value is the number of
     * bytes actually written out, not the length of the string. Following the
     * length, each character of the string is output, in sequence, using the
     * modified UTF-8 encoding for the character. If no exception is thrown, the
     * counter <code>written</code> is incremented by the total number of 
     * bytes written to the output stream. This will be at least two 
     * plus the length of <code>str</code>, and at most two plus 
     * thrice the length of <code>str</code>.
     *
     * @param      str   a string to be written.
     * @param      out   destination to write to
     * @return     The number of bytes written out.
     * @exception  IOException  if an I/O error occurs.
     */
    static int writeUTF(String str, DataOutput out) throws IOException {
	int strlen = str.length();
	int utflen = 0;
 	char[] charr = new char[strlen];
	int c, count;

	str.getChars(0, strlen, charr, 0);
 
	utflen = strlen * 3;
	byte[] bytearr = new byte[utflen+2];
	count = 2;
	for (int i = 0; i < strlen; i++) {
	    c = charr[i];
	    if ((c >= 0x0001) && (c <= 0x007F)) {
		bytearr[count++] = (byte) c;
	    } else if (c > 0x07FF) {
		bytearr[count++] = (byte) (0xE0 | ((c >> 12) & 0x0F));
		bytearr[count++] = (byte) (0x80 | ((c >>  6) & 0x3F));
		bytearr[count++] = (byte) (0x80 | ((c >>  0) & 0x3F));
	    } else {
		bytearr[count++] = (byte) (0xC0 | ((c >>  6) & 0x1F));
		bytearr[count++] = (byte) (0x80 | ((c >>  0) & 0x3F));
	    }
	}

	utflen = count - 2;

	if (utflen > 65535)
	    throw new UTFDataFormatException();

	bytearr[0] = (byte) ((utflen >>> 8) & 0xFF);
	bytearr[1] = (byte) ((utflen >>> 0) & 0xFF);

        out.write(bytearr, 0, count);

	return utflen + 2;
    }

    /**
     * Returns the current value of the counter <code>written</code>, 
     * the number of bytes written to this data output stream so far.
     * If the counter overflows, it will be wrapped to Integer.MAX_VALUE.
     *
     * @return  the value of the <code>written</code> field.
     * @see     java.io.DataOutputStream#written
     */
    public final int size() {
	return written;
    }
}