java自己主动生成验证码

代码结构：

web.xml

<?
xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 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_3_0.xsd">

	<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>*.action</url-pattern>
	</filter-mapping>

	<servlet>
		<servlet-name>ImageServlet</servlet-name>
		<servlet-class>com.wzs.ImageServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>ImageServlet</servlet-name>
		<url-pattern>/imageServlet</url-pattern>
	</servlet-mapping>

	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>

</web-app>

struts.xml

<?xml version="1.0" encoding="UTF-8"?
>
<!DOCTYPE struts PUBLIC
	"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
	"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
	<!-- 配置了系列常量 -->
	<constant name="struts.i18n.encoding" value="UTF-8" />

	<package name="wangzs" extends="struts-default">
		<action name="login" class="com.wzs.LoginAction">
			<result name="success">/welcome.jsp</result>
		</action>
		<!-- 让用户直接訪问该应用时列出全部视图页面 -->
		<action name="">
			<result>.</result>
		</action>
	</package>
</struts>

ImageServlet.java

package com.wzs;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ImageServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("image/jpeg");// 设置对应类型,告诉浏览器输出的内容为图片
		response.setHeader("Pragma", "No-cache");// 设置响应头信息，告诉浏览器不要缓存此内容
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expire", 0);
		RandomValidateCode randomValidateCode = new RandomValidateCode();
		try {
			randomValidateCode.getRandcode(request, response);// 输出图片方法
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}

RandomValidateCode.java

package com.wzs;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class RandomValidateCode {

	public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";// 放到session中的key
	private Random random = new Random();
	private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";// 随机产生的字符串

	private int width = 120;// 图片宽
	private int height = 26;// 图片高
	private int lineSize = 40;// 干扰线数量
	private int stringNum = 6;// 随机产生字符数量

	/*
	 * 获得字体
	 */
	private Font getFont() {
		return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
	}

	/*
	 * 获得颜色
	 */
	private Color getRandColor(int fc, int bc) {
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		int r = fc + random.nextInt(bc - fc - 16);
		int g = fc + random.nextInt(bc - fc - 14);
		int b = fc + random.nextInt(bc - fc - 18);
		return new Color(r, g, b);
	}

	/**
	 * 生成随机图片
	 */
	public void getRandcode(HttpServletRequest request, HttpServletResponse response) {
		HttpSession session = request.getSession();
		// BufferedImage类是具有缓冲区的Image类,Image类是用于描写叙述图像信息的类
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
		Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象能够在图像上进行各种绘制操作
		g.fillRect(0, 0, width, height);
		g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
		g.setColor(getRandColor(110, 133));
		// 绘制干扰线
		for (int i = 0; i <= lineSize; i++) {
			drowLine(g);
		}
		// 绘制随机字符
		String randomString = "";
		for (int i = 1; i <= stringNum; i++) {
			randomString = drowString(g, randomString, i);
		}
		session.removeAttribute(RANDOMCODEKEY);
		session.setAttribute(RANDOMCODEKEY, randomString);
		g.dispose();
		try {
			ImageIO.write(image, "JPEG", response.getOutputStream());// 将内存中的图片通过流动形式输出到client
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/*
	 * 绘制字符串
	 */
	private String drowString(Graphics g, String randomString, int i) {
		g.setFont(getFont());
		g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));
		String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
		randomString += rand;
		g.translate(random.nextInt(3), random.nextInt(3));
		g.drawString(rand, 13 * i, 16);
		return randomString;
	}

	/*
	 * 绘制干扰线
	 */
	private void drowLine(Graphics g) {
		int x = random.nextInt(width);
		int y = random.nextInt(height);
		int xl = random.nextInt(13);
		int yl = random.nextInt(15);
		g.drawLine(x, y, x + xl, y + yl);
	}

	/*
	 * 获取随机的字符
	 */
	public String getRandomString(int num) {
		return String.valueOf(randString.charAt(num));
	}
}

LoginAction.java

package com.wzs;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport {
	private String name;
	private String password;
	private String randomCode;

	@Override
	public String execute() throws Exception {
		ActionContext ctx = ActionContext.getContext();
		String randomcodekey = (String) ctx.getSession().get(RandomValidateCode.RANDOMCODEKEY);

		System.out.println("username:" + getName());
		System.out.println("密码:" + getPassword());
		System.out.println("图片显示验证码:" + randomcodekey + " | 用户输入验证码:" + randomCode);

		return null;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public String getRandomCode() {
		return randomCode;
	}

	public void setRandomCode(String randomCode) {
		this.randomCode = randomCode;
	}

}

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>验证码</title>
<script type="text/javascript">
	function refresh(obj) {
		obj.src = "imageServlet?" + Math.random();
	}
</script>
</head>
<body>
	<form action="login.action" method="post">
		<table>
			<tr>
				username：
				<input type="text" id="name" name="name" />
			</tr>
			<tr>
				密  码：
				<input type="text" id="password" name="password" />
			</tr>
			<tr>
				验证码：
				<input type="text" id="randomCode" name="randomCode" />
			</tr>
			<tr>
				<img title="点击更换" onclick="javascript:refresh(this);" src="imageServlet">
				<br />
			</tr>
			<tr>
				<input type="submit" value="submit">
			</tr>
		</table>
	</form>
</body>
</html>

welcome.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>My JSP 'welcome.jsp' starting page</title>


</head>

<body>
	登陆成功!
	<br>
</body>
</html>