package com.hongyuan.test;
 
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;
import java.util.UUID;
 
 
/*
 * 杂项（无符号数转换，字符串补齐，md5,uuid,随机数）
 */
public class SundryTest {
     
    //转成无符号数
    public static Number toUnsignedNumber(Number num){
        if(num instanceof Byte){
            return (Byte)num & 0xff;
        }else if(num instanceof Short){
            return (Short)num & 0xffff;
        }else if(num instanceof Integer){
            return (Integer)num & 0xffffffffL;
        }else{
            return -1;
        }
    }
    //左补齐
    public static String leftPad(String str,String pad,int len){
        String newStr=(str==null?"":str);
        while(newStr.length()<len){
            newStr=pad+newStr;
        }
        if(newStr.length()>len){
            newStr=newStr.substring(newStr.length()-len);
        }
        return newStr;
    }
    //右补齐
    public static String rightPad(String str,String pad,int len){
        String newStr=(str==null?"":str);
        while(newStr.length()<len){
            newStr=newStr+pad;
        }
        if(newStr.length()>len){
            newStr=newStr.substring(0, len);
        }
        return newStr;
    }
     
    //md5
    public static String md5(String str){
        StringBuilder sb=new StringBuilder();
        try {
            MessageDigest digest = MessageDigest.getInstance("MD5");
            byte[] message=digest.digest(str.getBytes());
            for(int i=0;i<message.length;i++){
                sb.append(leftPad(                                          //左补齐
                                Integer.toHexString(                        //转成16进制数   
                                    (Integer)toUnsignedNumber(message[i])), //转成无符号数
                            "0",2).toUpperCase());                          //转成大写
            }
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("不存在md5服务！");
        }
        return sb.toString();
    }
    //UUID
    public static String uuid(){
        return UUID.randomUUID().toString().replaceAll("-","").toUpperCase();
    }
     
    //随机数(包括min,不包括max)
    public static int random(int min,int max){
        if(min<=max){
            Random random=new Random();
            return random.nextInt(max-min)+min;
        }else{
            throw new IllegalArgumentException("无法处理一个不合法的数字区间！");
        }
 
    }
     
    public static void main(String[] args){
        System.out.println("MD5(123456):"+md5("123456"));
        System.out.println("UUID:"+uuid());
        System.out.println("随机数："+random(1,100));
    }
 
}