java - 实例化缓冲编写器的差异

Question

我想实例化一个缓冲写入器以写入套接字输出流。

    String cs = "UTF-8";
    OutputStream out = socket.getOutputStream();

    Writer writer1 = new BufferedWriter(
            new OutputStreamWriter(out, cs));

    Writer writer2 = new OutputStreamWriter(
            new BufferedOutputStream(out), cs);

    Writer writer3 = new BufferedWriter(
            new OutputStreamWriter(
                    new BufferedOutputStream(out), cs));

第一版和第二版之间有什么不明显的区别吗？哪个更适合写入套接字？第三个版本是不是有点“矫枉过正”？

Answer 1

第三个有点矫枉过正。

第一个是首选，因为它在通过文本到字节编码器发送数据之前缓冲数据，与一次一个字符相比，以 block 形式完成时性能更好。

OutputStreamWriter 的 javadoc甚至这样说:

For top efficiency, consider wrapping an OutputStreamWriter within a BufferedWriter so as to avoid frequent converter invocations. For example:

Writer out
  = new BufferedWriter(new OutputStreamWriter(System.out));