import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;
import java.util.UUID;

/*
 * 雜項（無符號數(shù)轉換，字符串補齊，md5,uuid,隨機數(shù)）
 */
public class SundryTest {

 //轉成無符號數(shù)
 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;
  }
 }
 //左補齊
 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;
 }
 //右補齊
 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(           //左補齊
        Integer.toHexString(      //轉成16進制數(shù) 
         (Integer)toUnsignedNumber(message[i])), //轉成無符號數(shù)
       "0",2).toUpperCase());       //轉成大寫
   }
  } catch (NoSuchAlgorithmException e) {
   throw new RuntimeException("不存在md5服務！");
  }
  return sb.toString();
 }
 //UUID
 public static String uuid(){
  return UUID.randomUUID().toString().replaceAll("-","").toUpperCase();
 }

 //隨機數(shù)(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("無法處理一個不合法的數(shù)字區(qū)間！");
  }

 }

 public static void main(String[] args){
  System.out.println("MD5(123456):"+md5("123456"));
  System.out.println("UUID:"+uuid());
  System.out.println("隨機數(shù)："+random(1,100));
 }

}