java实现无符号数转换、字符串补齐、md5、uuid、随机数示例

  • Z时代
  • 2024-01-10
  • 分类：IT

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)); }

}

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