Java Charset

package com.demo.test;

import java.nio.charset.Charset;
import java.util.Arrays;

/**
（1）在中国，字符串转化默认使用GBK编码
（2）转化表
英文（L） 中文（L） 混合（英文L1 + 中文L2）
DEFAULT(GBK) L 2*L L1 + 2*L2
ISO8859-1 L L L1 + L2
ASCII L L L1 + L2
GBK L 2*L L1 + 2*L2
UTF-8 L 3*L L1 + 3*L2
UNICODE 2*L+2 2*L+2 2*(L1 + L2)+2
*/
public class CharsetDemo {

public static void main(String[] args) {
System.out.println("ASCII " + Charset.isSupported("ASCII"));//true
System.out.println("Shift_JIS " + Charset.isSupported("Shift_JIS"));//true

System.out.println("ISO-8859-1 " + Charset.isSupported("ISO-8859-1"));//true
System.out.println("I-S-O-8859-1 " + Charset.isSupported("I-S-O-8859-1"));//false
System.out.println("ISO8859-1 " + Charset.isSupported("ISO8859-1"));//true
System.out.println("ISO8859_1 " + Charset.isSupported("ISO8859_1"));//true
//error: java.nio.charset.IllegalCharsetNameException
// System.out.println("ISO8859 1 " + Charset.isSupported("ISO8859 1"));
//ISO8859必须有第一版的标识否则不合法
System.out.println("ISO8859 " + Charset.isSupported("ISO8859"));//false

//ISO/IEC8859-1，又称Latin-1或“ 西欧语言”，但这里用Latin-1却是不合法的
System.out.println("Latin-1 " + Charset.isSupported("Latin-1"));//false

System.out.println("UTF8 " + Charset.isSupported("UTF8"));//true
System.out.println("UTF-8 " + Charset.isSupported("UTF-8"));//true
System.out.println("UTF_8 " + Charset.isSupported("UTF_8"));//false
//CharsetName跟大小写无关
System.out.println("Unicode " + Charset.isSupported("Unicode"));//true
System.out.println("uNiCoDe " + Charset.isSupported("uNiCoDe"));//true

String str1 = "hello world";//11位
System.out.println(Arrays.toString(str1.toCharArray()));
System.out.println(Arrays.toString(toCharBytes(str1)));
System.out.println(Arrays.toString(str1.getBytes()));//11位，[104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]
System.out.println(Arrays.toString(str1.getBytes(Charset.forName("ISO8859-1"))));//11位，[104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]
System.out.println(Arrays.toString(str1.getBytes(Charset.forName("ASCII"))));//11位，[104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]
System.out.println(Arrays.toString(str1.getBytes(Charset.forName("GBK"))));//11位，[104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]
System.out.println(Arrays.toString(str1.getBytes(Charset.forName("UTF-8"))));//11位，[104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]
System.out.println(Arrays.toString(str1.getBytes(Charset.forName("Unicode"))));//24位，[-2, -1, 0, 104, 0, 101, 0, 108, 0, 108, 0, 111, 0, 32, 0, 119, 0, 111, 0, 114, 0, 108, 0, 100]
System.out.println();

String str2 = "可惜不是你";//5位
System.out.println(Arrays.toString(str2.toCharArray()));
System.out.println(Arrays.toString(toCharBytes(str2)));
System.out.println(Arrays.toString(str2.getBytes()));//10位，[-65, -55, -49, -89, -78, -69, -54, -57, -60, -29]
System.out.println(Arrays.toString(str2.getBytes(Charset.forName("ISO8859-1"))));//5位，[63, 63, 63, 63, 63]
System.out.println(Arrays.toString(str2.getBytes(Charset.forName("ASCII"))));//5位，[63, 63, 63, 63, 63]
System.out.println(Arrays.toString(str2.getBytes(Charset.forName("GBK"))));//10位，[-65, -55, -49, -89, -78, -69, -54, -57, -60, -29]
System.out.println(Arrays.toString(str2.getBytes(Charset.forName("UTF-8"))));//15位，[-27, -113, -81, -26, -125, -100, -28, -72, -115, -26, -104, -81, -28, -67, -96]
System.out.println(Arrays.toString(str2.getBytes(Charset.forName("Unicode"))));//12位，[-2, -1, 83, -17, 96, -36, 78, 13, 102, 47, 79, 96]
System.out.println();

String str3 = "love!我爱你哟！";//5+5位
System.out.println(Arrays.toString(str3.toCharArray()));
System.out.println(Arrays.toString(toCharBytes(str3)));
System.out.println(Arrays.toString(str3.getBytes()));//15位，[108, 111, 118, 101, 33, -50, -46, -80, -82, -60, -29, -45, -76, -93, -95]
System.out.println(Arrays.toString(str3.getBytes(Charset.forName("ISO8859-1"))));//10位，[108, 111, 118, 101, 33, 63, 63, 63, 63, 63]
System.out.println(Arrays.toString(str3.getBytes(Charset.forName("ASCII"))));//10位，[108, 111, 118, 101, 33, 63, 63, 63, 63, 63]
System.out.println(Arrays.toString(str3.getBytes(Charset.forName("GBK"))));//15位，[108, 111, 118, 101, 33, -50, -46, -80, -82, -60, -29, -45, -76, -93, -95]
System.out.println(Arrays.toString(str3.getBytes(Charset.forName("UTF-8"))));//20位，[108, 111, 118, 101, 33, -26, -120, -111, -25, -120, -79, -28, -67, -96, -27, -109, -97, -17, -68, -127]
System.out.println(Arrays.toString(str3.getBytes(Charset.forName("Unicode"))));//22位，[-2, -1, 0, 108, 0, 111, 0, 118, 0, 101, 0, 33, 98, 17, 114, 49, 79, 96, 84, -33, -1, 1]
}

public static byte[] toCharBytes(String str) {
char[] charArr = str.toCharArray();
byte[] byteArr = new byte[charArr.length*2];
for(int i=0;i<charArr.length;i++) {
//当字符是英文时，该位的编码与ASCII和ISO8859-1均相同
byteArr[2*i] = (byte)(charArr[i] & 0xFF);
//当字符是英文的时候，高位是0；如果字符是中文，那么高位不为0。并且该编码也与GBK、UTF8、Unicode都不同
byteArr[2*i+1] = (byte)((charArr[i] & 0xFF00) >>> 8);
}
return byteArr;
}
}