验证码（正则表达式）

package term;import java.util.Random;import java.util.regex.Pattern;/*需求生成验证码 并以 数字 字母 数字 字母形式*/public class Demo {private int len;private String s= "qwertyuiopasdfghjklzxcvbnm1234567890";public Demo(){this.len = 4;}public Demo(int len){this.len = len;}public static void main(String[] args) {Demo d = new Demo();System.out.println(d.getCode());}//生成验证码并返回public String getCode(){Random r = new Random();StringBuilder getS = new StringBuilder();char[] arr = new char[len];//正则校验String jyCode = "[0-9][a-z][0-9][a-z]{5}";while (true) {for (int i = 0; i < len; i++) {arr[i] = s.charAt(r.nextInt(s.length()));getS.append(arr[i]);}if(Pattern.matches(jyCode,getS)) //使用matches方法进行 匹配对比 成功返回break;getS.delete(0,getS.length()); //失败 删除后重新随机}return getS.toString();}}

package term;import java.util.regex.Matcher;import java.util.regex.Pattern;public class Test {public static void main(String[] args) {String s = "$1231cxzcd$13";//先创建一个Pattern 对象 模式Pattern pattern = pile("[$][0-9]+");//再创建一个匹配器对象Matcher matcher = pattern.matcher(s);//public boolean find() 判断是否有 满足正则表达式的内容String[] arry = {};int i = 0;while (matcher.find()){//public String group(int group) 返回满足正则表达式内容System.out.println("有"+matcher.group(0));arry[i] = matcher.group(0);i++;}}}