com.alibaba.metrics.reporter.file.BufferedOutputStream Maven / Gradle / Ivy
package com.alibaba.metrics.reporter.file;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
*
* 去掉synchronized，非thread safe，只能一个线程使用
*
* 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
* @since JDK1.0
*/
public
class BufferedOutputStream extends FilterOutputStream {
/**
* The internal buffer where data is stored.
*/
protected byte buf[];
/**
* 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.
*/
protected int count;
/**
* Creates a new buffered output stream to write data to the
* specified underlying output stream.
*
* @param out the underlying output stream.
*/
public BufferedOutputStream(OutputStream out) {
this(out, 8192);
}
/**
* 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.
*/
public BufferedOutputStream(OutputStream out, int size) {
super(out);
if (size <= 0) {
throw new IllegalArgumentException("Buffer size <= 0");
}
buf = new byte[size];
}
/** Flush the internal buffer */
private void flushBuffer() throws IOException {
if (count > 0) {
out.write(buf, 0, count);
count = 0;
}
}
/**
* Writes the specified byte to this buffered output stream.
*
* @param b the byte to be written.
* @exception IOException if an I/O error occurs.
*/
public void write(int b) throws IOException {
if (count >= buf.length) {
flushBuffer();
}
buf[count++] = (byte)b;
}
/**
* 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.
*/
public void write(byte b[], int off, int len) throws IOException {
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;
}
/**
* 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
*/
public void flush() throws IOException {
flushBuffer();
out.flush();
}
}