content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  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 <tt>0</tt> through <tt>buf.length</tt>; elements
       * <tt>buf[0]</tt> through <tt>buf[count-1]</tt> 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 &lt;= 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 <code>len</code> bytes from the specified byte array
       * starting at offset <code>off</code> to this buffered output stream.
       *
       * <p> 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
       * <code>BufferedOutputStream</code>s 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();
      }
  }
  