Java实现验证码具体代码

这里实现我使用到了struts2模拟一个登录功能来验证java实现的验证码功能。

Java实现验证码的步骤：

1、创建RandomImageGenerator.java类，该类实现验证码图片的生成

2、创建一个servlet类，RandomImageServlet.java，将生成的验证码输出到页面

3、创建一个Action类，LoginAction.java，控制登录

4、配置struts.xml一个web.xml文件

5、编写页面

具体实现用代码表达

1、创建RandomImageGenerator.java类

代码如下:

package com.tenghu.code;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;

/**
 * 验证码生成类
 * @author xiaohu
 *
 */
public class RandomImageGenerator {
 //创建Random对象
 static Random random=new Random();
 //随机生成包含验证码字符串
 public static String random(int num){
  //初始化种子
  String[] str={"0","1","2","3","4","5","6","7","8","9",
       "a","b","c","d","e","f","g","h","i","j",
       "k","l","m","n","p","q","r","s","t"};
  int number=str.length;
  //接收随机字符
  String text = "";
  //随机产生4个字符的字符串
  for(int i=0;i<num;i++){
   text+=str[random.nextInt(number)];
  }
  return text;
 }
 /**
  * 随机产生定义的颜色
  *
  * @return
  */
 private static Color getRandColor() {
  Random random = new Random();
  Color color[] = new Color[10];
  color[0] = new Color(32, 158, 25);
  color[1] = new Color(218, 42, 19);
  color[2] = new Color(31, 75, 208);
  color[3] = new Color(0, 102, 182);
  color[4] = new Color(171, 0, 85);
  return color[random.nextInt(5)];
 }
 /**
  * 产生随机字体
  *
  * @return
  */
 private static Font getFont() {
  Random random = new Random();
  Font font[] = new Font[5];
  font[0] = new Font("Ravie", Font.BOLD, 30);
  font[1] = new Font("Antique Olive Compact", Font.BOLD, 30);
  font[2] = new Font("Forte", Font.BOLD, 30);
  font[3] = new Font("Wide Latin", Font.BOLD, 30);
  font[4] = new Font("Gill Sans Ultra Bold", Font.BOLD, 30);
  return font[random.nextInt(5)];
 }
 /**
  * 生成图片
  * @throws IOException
  */
 public static void render(String randomStr,OutputStream out,int width,int height) throws IOException{
  //在内存中创建图像
  BufferedImage bi=new BufferedImage(width, height, BufferedImage.TYPE_BYTE_INDEXED);
  //获取图形上下文
  Graphics2D g=(Graphics2D) bi.getGraphics();
  //话边框
  g.setColor(Color.white);
  g.fillRect(0, 0, width, height);
  g.setFont(getFont());
  g.setColor(Color.BLACK);
  //画认证码，每个认证码在不同的水平位置
  String str1[]=new String[randomStr.length()];
  for(int i=0;i<str1.length;i++){
   str1[i]=randomStr.substring(i,i+1);
   int w=0;
   int x=(i+1)%3;
   //随机生成验证码字符水平偏移量
   if(x==random.nextInt(7)){
    w=30-random.nextInt(7);
   }else{
    w=30+random.nextInt(7);
   }
   //随机生成颜色
   g.setColor(getRandColor());
   g.drawString(str1[i], 20*i+10, w);
  }
  //随机产生干扰点，并用不同的颜色表示，事图像的认证码不易被其他程序探测到
  for(int i=0;i<100;i++){
   int x=random.nextInt(width);
   int y=random.nextInt(height);
   Color color=new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
   //随机画各种颜色的线
   g.setColor(color);
   g.drawOval(x, y, 0, 0);
  }
  //画干扰线
  for(int i=0;i<15;i++){
   int x=random.nextInt(width);
   int y=random.nextInt(height);
   int x1=random.nextInt(width);
   int y1=random.nextInt(height);
   Color color=new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
   //随机画各种颜色线
   g.setColor(color);
   g.drawLine(x, y, x1, y1);
  }
  //图像生效
  g.dispose();
  //输出页面
  ImageIO.write(bi, "jpg", out);
 }
 public static void main(String[] args) throws FileNotFoundException, IOException {
  //获取随机字符串
  String randomStr=random(5);
  System.out.println(randomStr);
  //生成图片
  render(randomStr, new FileOutputStream("D:\\test.jpg"),130,40);
 }
}

2、创建RandomImageServlet.java

代码如下:

package com.tenghu.code.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.tenghu.code.RandomImageGenerator;

public class RandomImageServlet extends HttpServlet {
 //图片宽度
 int width=0;
 //图片高度
 int height=0;
 //图片上随机字符个数
 int randomStrNum=0;
 public void destroy() {
 }
 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doPost(request, response);
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  request.setCharacterEncoding("UTF-8");
  //获取HttpSession对象
  HttpSession session=request.getSession();
  //获取随机字符串
  String randomStr=RandomImageGenerator.random(randomStrNum);
  if(null!=session){
   //设置参数
   session.setAttribute("randomStr", randomStr);
   //设置响应类型,输出图片客户端不缓存
   response.setDateHeader("Expires", 1L); 
   response.setHeader("Cache-Control", "no-cache, no-store, max-age=0");
   response.addHeader("Pragma", "no-cache");
   response.setContentType("image/jpeg"); 
   //输出到页面
   RandomImageGenerator.render(randomStr, response.getOutputStream(), width, height);
  }
 }
 public void init() throws ServletException {
  //获取宽度
  width=Integer.parseInt(this.getInitParameter("width"));
  //获取高度
  height=Integer.parseInt(this.getInitParameter("height"));
  //获取个数
  randomStrNum=Integer.parseInt(this.getInitParameter("num"));
 }
}

3、创建LoginAction.java类

代码如下:

package com.tenghu.code.action;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport{
 //用户名
 private String userName;
 //密码
 private String password;
 //验证码
 private String code;
 private InputStream inputStream;
 public InputStream getResult(){
  return inputStream;
 }
 //成功
 public String success() throws Exception{
  return SUCCESS;
 }
 //测试登录
 public String testLogin() throws Exception{
  //获取图片的验证码
  String randomStr=(String) ActionContext.getContext().getSession().get("randomStr");
  if(code.trim().equalsIgnoreCase(randomStr)){
   if("admin".equals(userName.trim())&&"admin".equals(password.trim())){
    //成功
    inputStream=new ByteArrayInputStream("1".getBytes("UTF-8"));
   }else{
    //用户名或密码错误
    inputStream=new ByteArrayInputStream("2".getBytes("UTF-8"));
   }
  }else{
   //验证码错误
   inputStream=new ByteArrayInputStream("0".getBytes("UTF-8"));
  }
  return "result";
 }
 public String getUserName() {
  return userName;
 }
 public void setUserName(String userName) {
  this.userName = userName;
 }
 public String getPassword() {
  return password;
 }
 public void setPassword(String password) {
  this.password = password;
 }
 public String getCode() {
  return code;
 }
 public void setCode(String code) {
  this.code = code;
 }
}

4、配置struts.xml、web.xml文件

代码如下:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
 "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
 "http://struts.apache.org/dtds/struts-2.3.dtd">
<struts> 
 <package name="installs" extends="struts-default">
  <action name="login" class="com.tenghu.code.action.LoginAction">
   <!-- 登录成功到success.jsp页面 -->
   <result name="success">success.jsp</result>
   <!-- 登录验证返回的数据 -->
   <result name="result" type="stream">
    <param name="contentType">text/html</param>
    <param name="inputName">result</param>
   </result>
  </action>
 </package>
</struts>

代码如下:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
 xmlns="http://java.sun.com/xml/ns/javaee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
 http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>RandomImageServlet</servlet-name>
    <servlet-class>com.tenghu.code.servlet.RandomImageServlet</servlet-class>
    <!-- 初始化图片宽度 -->
    <init-param>
     <param-name>width</param-name>
     <param-value>130</param-value>
    </init-param>
    <!-- 初始化图片高度 -->
    <init-param>
     <param-name>height</param-name>
     <param-value>40</param-value>
    </init-param>
    <!-- 初始化图片随机数个数 -->
    <init-param>
     <param-name>num</param-name>
     <param-value>4</param-value>
    </init-param>
  </servlet>

<servlet-mapping>
    <servlet-name>RandomImageServlet</servlet-name>
    <url-pattern>/verification.do</url-pattern>
  </servlet-mapping>
  <!-- 配置struts核心过滤器 -->
  <filter>
   <filter-name>struts2</filter-name>
   <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
  </filter>
  <filter-mapping>
   <filter-name>struts2</filter-name>
   <url-pattern>/*</url-pattern>
  </filter-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

5、编写测试页面

代码如下:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">

<title>My JSP 'index.jsp' starting page</title>
 <script type="text/javascript" src="js/jquery-1.10.2.min.js"></script>
 <script type="text/javascript" src="js/jquery.form.js"></script>
 <script type="text/javascript">
  $(document).ready(function(){
   CODE.initCode();
   //验证输入
   function checkInput(){
    if($('#userName').val()==''){
     alert('用户名不能为空！');
     return false;
    }
    if($('#password').val()==''){
     alert('密码不能为空！');
     return false;
    }
    if($('#code').val()==''){
     alert('验证码不能为空！');
     return false;
    }
    return true;
   }

//点击按钮
   $('#btn').click(function(){
    if(checkInput()==true){
     $('#login_request').ajaxSubmit({
      url:'login!testLogin',
      cache:false,
      type:'POST',
      success:function(data){
       if(data==0){
        alert('验证码错误！');
        //改变验证码
        CODE.initCode();
       }else if(data==1){
        alert('登录成功！');
        //提交到登录成功页面
        $('#login_request')[0].submit();
       }else if(data==2){
        alert('用户名或密码错误！');
        //改变验证码
        CODE.initCode();
       }
      },
      error:function(e){
       alert('出错了！');
      }
     });
     }
   });
  });
  var CODE={
    //初始化化验证码
    initCode:function(){
     $("#code_img").attr("src","verification.do?rmd="+new Date().getTime())//如果需要点击图片改变图片的内容，则必须添加时间搓
     .click(function(){
      $(this).attr("src","verification.do?rmd="+new Date().getTime());
     }); 
    }};
 </script>
  </head>

<body>
   <form action="login!success" id="login_request" method="post">
    UserName:<input type="text" id="userName" name="userName"/><br/>
    Password:<input type="password" id="password" name="password"/><br>
    Verification_Code:<input type="text" id="code" name="code"/><img id="code_img" style="position:relative;top:8px;height:25px"><br>
    <input type="button" id="btn" value="登录"/>
   </form>
  </body>
</html>

成功页面就部贴出来了，就是一段文字而已
显示结果：