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：
