Java IO（输入输出）

1. System.out、System.in

• System 内部：

  public final static InputStream in = null;public final static PrintStream out = null;

  • 二者均是实例化后的对象；

2. PrintStream、PrintWriter

Writing to console with System.out and PrintWriter

• PrintStream：a stream of bytes，字节流；
  
  • 使用平台默认编码，

• PrintWriter：a stream of characters，字符流；

  • 可以自定义编码，通过 OutputStreamWriter

  private static final CHARSET_NAME = "UTF-8";PrintWriter out = new PrintWriter(new OutputStreamWriter(output, CHARSET_NAME));