生成验证码

//生成四位的验证码
        
        
        //利用split截取
        
        String str = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        
        String []str1 = str.split("");//分割字符串，并生成数组
        
//        for(String x:str1){
//            
//            System.out.println(x);
//        }
        String Code = "";//声明一个空的字符串
        
        Random ran = new Random();
        
        for(int i = 0;i<4;i++){
            
            int j = ran.nextInt(62);
            
            if(j == 0){                    //去除split分割出来的那个空的char
                
                Code = Code + str1[j+1];
            }
            else{
                
                Code = Code + str1[j];
            }
        }
        System.out.println("生成的验证码1是："+Code);
        
        
        //利用subSting来分割
        
        str = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        
        Random ran1 = new Random();
        
        System.out.print("生成的验证码2是：");
        
        for(int a = 0;a<4;a++){            //循环四次截取四个字符串
            
            int i = ran1.nextInt(str.length()-1);
            
            System.out.print(str.substring(i,i+1));
        }
        System.out.println();
        
        

运行的结果：