java - 我应该先转换字节流，缓冲流还是字符流？

Question

要获取给定字节流的缓冲字符流，我应该先将字节流转换为缓冲流还是字符流？

1. 给定一个 OutputStream 对象 os(例如 FileOutputStream对象或 System.out)，似乎有两种方法可以获取缓冲字符流:

   new BufferedWriter(new OutputStreamWriter(os));
   
   new OutputStreamWriter(new BufferedOutputStream(os));
   

   它们之间有什么区别？

2. 给定一个 InputStream 对象 is (例如 FileInputStream 对象或 System.in )，似乎有两种方法可以获取缓冲的字符流:

   new BufferedReader(new InputStreamReader(is));
   
   new InputStreamReader(new BufferedInputStream(is));
   

   它们之间有什么区别？

Answer 1

1. 如 javadoc 中所述 OutputStreamWriter

The characters passed to the write() methods are not buffered.
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));

由于转换后的结果字节会累积在缓冲区中，因此无需在 OutputStreamWriter 之后通过管道传入 BufferedStream

因此，传统的方法是使用:

new BufferedWriter(new OutputStreamWriter(os));

InputStreamReader 的类似原因

用途:

new BufferedReader(new InputStreamReader(is));