编码总结

public static void main(String args[]) {

		try {
			byte[] b = "汉字a".getBytes("Unicode");

			System.out.println(b.length);
			b = "汉字a".getBytes("GBK");

			System.out.println(b.length);
			b = "汉字a".getBytes("UTF-8");

			System.out.println(b.length);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}

Unicode 所有字符2个字节编码+2个字节头

UTF-8 汉字*3 字符*1

gbk/gb2312 汉字*2 字符*1

所以是8

5

7

-----

static void show(byte[] b) {
for (int i = 0; i < b.length; i++)

System.out.print(Integer.toBinaryString(b[i]&0xff)+“ ”);
     
}

以汉字汉为例

unicode 

11111110 11111111 1101100 1001001 ---4 unicode

10111010 10111010 ---2 gbk
11100110 10110001 10001001 ---3utf-8

utf-8 1110xxx 3个字节就是3个1

10xxxxxx

10xxxxxx