dataoutputstream.java

已经移植好的java虚拟机

/*
 * Copyright 1994-2002 Sun Microsystems, Inc. All Rights Reserved.
 *
 * This software is the proprietary information of Sun Microsystems, Inc.
 * Use is subject to license terms.
 *
 */

package java.io;

/**
 * A data input 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 1.31, 12/04/99 (CLDC 1.0, Spring 2000)
 * @see     java.io.DataInputStream
 * @since   JDK1.0, CLDC 1.0
 */
public
class DataOutputStream extends OutputStream implements DataOutput {

    /**
     * The output stream.
     */
    protected OutputStream out;

    /**
     * Creates a new data output stream to write data to the specified
     * underlying output stream.
     *
     * @param   out   the underlying output stream, to be saved for later
     *                use.
     */
    public DataOutputStream(OutputStream out) {
        this.out = out;
    }

    /**
     * Writes the specified byte (the low eight bits of the argument
     * <code>b</code>) to the underlying output stream.
     * <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.
     */
    public void write(int b) throws IOException {
        out.write(b);
    }

    /**
     * Writes <code>len</code> bytes from the specified byte array
     * starting at offset <code>off</code> to the underlying output stream.
     *
     * @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.
     */
    public void write(byte b[], int off, int len) throws IOException {
        out.write(b, off, 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>DataOutputStream</code>
     * calls the <code>flush</code> method of its underlying output stream.
     *
     * @exception  IOException  if an I/O error occurs.
     */
    public void flush() throws IOException {
        out.flush();
    }

    /**
     * Closes this output stream and releases any system resources
     * associated with the stream.
     * <p>
     * The <code>close</code> method
     * calls its <code>flush</code> method, and then calls the
     * <code>close</code> method of its underlying output stream.
     *
     * @exception  IOException  if an I/O error occurs.
     */
    public void close() throws IOException {
        out.close();
    }

    /**
     * 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>.
     *
     * @param      v   a <code>boolean</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     */
    public final void writeBoolean(boolean v) throws IOException {
        write(v ? 1 : 0);
    }

    /**
     * Writes out a <code>byte</code> to the underlying output stream as
     * a 1-byte value.
     *
     * @param      v   a <code>byte</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     */
    public final void writeByte(int v) throws IOException {
        write(v);
    }

    /**
     * Writes a <code>short</code> to the underlying output stream as two
     * bytes, high byte first.
     *
     * @param      v   a <code>short</code> to be written.
     * @exception  IOException  if an I/O error occurs.
     */
    public final void writeShort(int v) throws IOException {
        write((v >>> 8) & 0xFF);
        write((v >>> 0) & 0xFF);
    }

    /**
     * Writes a <code>char</code> to the underlying output stream as a
     * 2-byte value, high byte first.
     * @param      v   a <code>char</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     */
    public final void writeChar(int v) throws IOException {
        write((v >>> 8) & 0xFF);
        write((v >>> 0) & 0xFF);
    }

    /**
     * Writes an <code>int</code> to the underlying output stream as four
     * bytes, high byte first.
     *
     * @param      v   an <code>int</code> to be written.
     * @exception  IOException  if an I/O error occurs.
     */
    public final void writeInt(int v) throws IOException {
        write((v >>> 24) & 0xFF);
        write((v >>> 16) & 0xFF);
        write((v >>>  8) & 0xFF);
        write((v >>>  0) & 0xFF);
    }

    /**
     * Writes a <code>long</code> to the underlying output stream as eight
     * bytes, high byte first.
     *
     * @param      v   a <code>long</code> to be written.
     * @exception  IOException  if an I/O error occurs.
     */
    public final void writeLong(long v) throws IOException {
        write((int)(v >>> 56) & 0xFF);
        write((int)(v >>> 48) & 0xFF);
        write((int)(v >>> 40) & 0xFF);
        write((int)(v >>> 32) & 0xFF);
        write((int)(v >>> 24) & 0xFF);
        write((int)(v >>> 16) & 0xFF);
        write((int)(v >>>  8) & 0xFF);
        write((int)(v >>>  0) & 0xFF);
    }

    /**
     * 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.
     *
     * @param      s   a <code>String</code> value to be written.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.DataOutputStream#writeChar(int)
     */
    public final void writeChars(String s) throws IOException {
        int len = s.length();
        for (int i = 0 ; i < len ; i++) {
            int v = s.charAt(i);
            write((v >>> 8) & 0xFF);
            write((v >>> 0) & 0xFF);
        }
    }

    /**
     * Writes a string to the underlying output stream using 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 UTF-8 encoding
     * for the character.
     *
     * @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 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
     * UTF-8 encoding for the character.
     *
     * @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 final int writeUTF(String str, DataOutput out) throws IOException {
        return com.sun.cldc.io.GeneralBase.writeUTF(str, out);
    }

}