Java中如何判断中文字符串长度

import java.io.UnsupportedEncodingException;
public class test {
	public static void main(String[] args) throws UnsupportedEncodingException{
		String str = "123java编程";
		System.out.println("length():" + str.length());
		System.out.println("ASCII:" + getStringLength(str));
		System.out.println("正则:" + getStringLengthRegex(str));  
        System.out.println("GBK:" + getStringLengthCode(str,"GBK"));  
        System.out.println("UTF-8:" + getStringLengthCode(str,"UTF-8"));  
	}
	public static int getStringLength(String s){  
        int length = 0;  
        for(int i = 0; i < s.length(); i++)  
        {  
            int ascii = Character.codePointAt(s, i);  
            if(ascii >= 0 && ascii <=255)  
                length++;  
            else  
                length += 2;  
        }  
        return length;  
    }
	/*基本原理是将字符串中所有的非标准字符（双字节字符）替换成两个标准字符（**，或其他的也可以）。这样就可以直接例用length方法获得字符串的字节长度了*/  
    public static  int getStringLengthRegex(String s) {  
        s = s.replaceAll("[^\\x00-\\xff]", "**");  
        int length = s.length();  
        return length;  
    } 
    /*按特定的编码格式获取长度*/  
    public static int getStringLengthCode(String str, String code) throws UnsupportedEncodingException{  
        return str.getBytes(code).length;  
    } 
}
/*
输出结果：
length():9
ASCII:11
正则:11
GBK:11
UTF-8:13
*/

public class Char_cn {
 public static void main(String[] args) {
  // TODO Auto-generated method stub
  String haha = "呵呵呵呵abcd";
  int true_num = String_length(haha);
  System.out.println("true" + true_num);
  int false_num = haha.length();
  System.out.print("flase" + false_num);
 }
 public static int String_length(String value) {
  int valueLength = 0;
  String chinese = "[\u4e00-\u9fa5]";
  for (int i = 0; i < value.length(); i++) {
   String temp = value.substring(i, i + 1);
   if (temp.matches(chinese)) {
    valueLength += 2;
   } else {
    valueLength += 1;
   }
  }
  return valueLength;
 }
}

true12
false8

Regex.IsMatch(“中文”,”^[/u4e00-/u9fa5]”)；

！Regex.IsMatch(“中文”,@”[a-zA-Z]”)；