FileDocCategorySizeDatePackage
BufferedOutputStream.javaAPI DocJava SE 5 API3984Fri Aug 26 14:56:58 BST 2005java.io

BufferedOutputStream

public class BufferedOutputStream extends FilterOutputStream
The class implements a buffered output stream. By setting up such an output stream, an application can write bytes to the underlying output stream without necessarily causing a call to the underlying system for each byte written.
author
Arthur van Hoff
version
1.33, 12/19/03
since
JDK1.0

Fields Summary
protected byte[]
buf
The internal buffer where data is stored.
protected int
count
The number of valid bytes in the buffer. This value is always in the range 0 through buf.length; elements buf[0] through buf[count-1] contain valid byte data.
Constructors Summary
public BufferedOutputStream(OutputStream out)
Creates a new buffered output stream to write data to the specified underlying output stream.

param
out the underlying output stream.

	this(out, 8192);
public BufferedOutputStream(OutputStream out, int size)
Creates a new buffered output stream to write data to the specified underlying output stream with the specified buffer size.

param
out the underlying output stream.
param
size the buffer size.
exception
IllegalArgumentException if size <= 0.

	super(out);
        if (size <= 0) {
            throw new IllegalArgumentException("Buffer size <= 0");
        }
	buf = new byte[size];
Methods Summary
public synchronized voidflush()
Flushes this buffered output stream. This forces any buffered output bytes to be written out to the underlying output stream.

exception
IOException if an I/O error occurs.
see
java.io.FilterOutputStream#out

        flushBuffer();
	out.flush();
private voidflushBuffer()
Flush the internal buffer

        if (count > 0) {
	    out.write(buf, 0, count);
	    count = 0;
        }
public synchronized voidwrite(int b)
Writes the specified byte to this buffered output stream.

param
b the byte to be written.
exception
IOException if an I/O error occurs.

	if (count >= buf.length) {
	    flushBuffer();
	}
	buf[count++] = (byte)b;
public synchronized voidwrite(byte[] b, int off, int len)
Writes len bytes from the specified byte array starting at offset off to this buffered output stream.

Ordinarily this method stores bytes from the given array into this stream's buffer, flushing the buffer to the underlying output stream as needed. If the requested length is at least as large as this stream's buffer, however, then this method will flush the buffer and write the bytes directly to the underlying output stream. Thus redundant BufferedOutputStreams will not copy data unnecessarily.

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.

	if (len >= buf.length) {
	    /* If the request length exceeds the size of the output buffer,
    	       flush the output buffer and then write the data directly.
    	       In this way buffered streams will cascade harmlessly. */
	    flushBuffer();
	    out.write(b, off, len);
	    return;
	}
	if (len > buf.length - count) {
	    flushBuffer();
	}
	System.arraycopy(b, off, buf, count, len);
	count += len;