JAVA的输出流 - java.io.OutputStream

 

继承关系

同InputStream一样实现了closeable接口外 实现了Flushable接口 flush方法

 

主要方法

 

 

 

/**
     * Writes the specified byte to this output stream. The general
     * contract for write is that one byte is written
     * to the output stream. The byte to be written is the eight
     * low-order bits of the argument b. The 24
     * high-order bits of b are ignored.
     * 

     * Subclasses of OutputStream must provide an
     * implementation for this method.
     *
     * @param      b   the byte.
     * @exception  IOException  if an I/O error occurs. In particular,
     *             an IOException may be thrown if the
     *             output stream has been closed.

        主要方法 把参数b写入流中

     */
    public abstract void write(int b) throws IOException;

 
    public void write(byte b[]) throws IOException {
        write(b, 0, b.length);
    }

  
    public void write(byte b[], int off, int len) throws IOException {
        if (b == null) {
            throw new NullPointerException();
        } else if ((off < 0) || (off > b.length) || (len < 0) ||
                   ((off + len) > b.length) || ((off + len) < 0)) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return;
        }
        for (int i = 0 ; i < len ; i++) {
            write(b[off + i]);
        }
    }

 /**
     * Flushes this output stream and forces any buffered output bytes
     * to be written out. The general contract of flush is
     * that calling it is an indication that, if any bytes previously
     * written have been buffered by the implementation of the output
     * stream, such bytes should immediately be written to their
     * intended destination.
     * 

     * If the intended destination of this stream is an abstraction provided by
     * the underlying operating system, for example a file, then flushing the
     * stream guarantees only that bytes previously written to the stream are
     * passed to the operating system for writing; it does not guarantee that
     * they are actually written to a physical device such as a disk drive.
     * 

     * The flush method of OutputStream does nothing.
     *
     * @exception  IOException  if an I/O error occurs.



        实现该方法 流中的bytes会被刷入intended destination中 
        如果intended destination是操作系统提供并管理的 该方法不会立刻写入
        何时真正写入由操作系统决定  
     */
    public void flush() throws IOException {
    }