登录的时候，经常需要输入验证码，我们来写一个验证码产生的函数，包括数字，大写字母，小写字母各种情况的组合
VerifyCode.java
1 package com.xiejiaohui.util; 2 3 import java.util.Random; 4 5 /** 6 * 验证码产生器 2016-01-24 7 * 8 * @author xiejiaohui 9 * 10 */ 11 public class VerifyCode { 12 13 /** 14 * 产生验证码 15 * 16 * @param type 17 * @param length 18 * @param exChars 19 * @return 20 */ 21 public static String generateTextCode(int type, int length, String exChars) { 22 if (length <= 0) { 23 return ""; 24 } 25 StringBuffer code = new StringBuffer(); 26 int i = 0; 27 Random r = new Random(); 28 switch (type) { 29 default: 30 break; 31 case 0: // 仅数字 32 while (i < length) { 33 int t = r.nextInt(10); 34 if (exChars == null || exChars.indexOf((new StringBuilder(String.valueOf(t))).toString()) < 0) { 35 code.append(t); 36 i++; 37 } 38 } 39 break; 40 case 1: // 仅字母（即大写字母、小写字母混合） 41 while (i < length) { 42 int t = r.nextInt(123); 43 if ((t >= 97 || t >= 65 && t <= 90) && (exChars == null || exChars.indexOf((char) t) < 0)) { 44 code.append((char) t); 45 i++; 46 } 47 } 48 break; 49 case 2: // 数字、大写字母、小写字母混合 50 while (i < length) { 51 int t = r.nextInt(123); 52 if ((t >= 97 || t >= 65 && t <= 90 || t >= 48 && t <= 57) 53 && (exChars == null || exChars.indexOf((char) t) < 0)) { 54 code.append((char) t); 55 i++; 56 } 57 } 58 break; 59 case 3: // 数字、大写字母混合 60 while (i < length) { 61 int t = r.nextInt(91); 62 if ((t >= 65 || t >= 48 && t <= 57) && (exChars == null || exChars.indexOf((char) t) < 0)) { 63 code.append((char) t); 64 i++; 65 } 66 } 67 break; 68 case 4: // 数字、小写字母混合 69 while (i < length) { 70 int t = r.nextInt(123); 71 if ((t >= 97 || t >= 48 && t <= 57) && (exChars == null || exChars.indexOf((char) t) < 0)) { 72 code.append((char) t); 73 i++; 74 } 75 } 76 break; 77 case 5: // 仅大写字母 78 while (i < length) { 79 int t = r.nextInt(91); 80 if (t >= 65 && (exChars == null || exChars.indexOf((char) t) < 0)) { 81 code.append((char) t); 82 i++; 83 } 84 } 85 break; 86 case 6: // 仅小写字母 87 while (i < length) { 88 int t = r.nextInt(123); 89 if (t >= 97 && (exChars == null || exChars.indexOf((char) t) < 0)) { 90 code.append((char) t); 91 i++; 92 } 93 } 94 break; 95 } 96 return code.toString(); 97 } 98 99 public static void main(String[] args) { 100 // 10以内的随机数: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 不包括10 101 Random random = new Random(); 102 System.out.println(random.nextInt(10)); 103 104 // 大写字母 105 for(int i = 65; i <= 90; i++) { 106 System.out.print((char)i); 107 System.out.print(" "); 108 } 109 System.out.println(); 110 111 // 小写字母 112 for(int i = 97; i <= 122; i++) { 113 System.out.print((char)i); 114 System.out.print(" "); 115 } 116 System.out.println(); 117 118 // 数字 119 for(int i = 48; i <= 57; i++) { 120 System.out.print((char)i); 121 System.out.print(" "); 122 } 123 System.out.println(); 124 125 System.out.println(VerifyCode.generateTextCode(0, 32, "0")); // 数字 126 System.out.println(VerifyCode.generateTextCode(1, 32, "l")); // 大写字母和小写字母组合 127 System.out.println(VerifyCode.generateTextCode(2, 32, "l")); // 数字大写字母、小写字母组合 128 System.out.println(VerifyCode.generateTextCode(3, 32, "0")); // 数字和大写字母组合 129 System.out.println(VerifyCode.generateTextCode(4, 32, "0")); // 数字和小写字母组合 130 System.out.println(VerifyCode.generateTextCode(5, 32, "Z")); // 大写字母 131 System.out.println(VerifyCode.generateTextCode(6, 32, "o")); // 小写字母 132 133 } 134 135 }
输出：
1 5 2 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 3 a b c d e f g h i j k l m n o p q r s t u v w x y z 4 0 1 2 3 4 5 6 7 8 9 5 62651637842124942893714462981794 6 YMFcVREgxazamXFoAgkjKJimFohafisJ 7 sZecd9cNP9hufE3ZrQIVxEKtR6tkUkVj 8 3MJUZ6JD1QZSC4RNR6C4VC6YT4DWHHBY 9 pdqdwia9csl8e89xneh1lvvnrh2btkdz 10 HMTFHCGUXVABGIVSLRCWAGQDABYKQVDB 11 uwikqkqaeiemvphctmyhxctdsfwrkkgh