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

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

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

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

<?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>

<?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

<%@ 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：