servlet和jsp写一个图片验证码

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//定义生成验证码图片的Servlet：

import java.awt.Color;

import java.awt.Graphics2D;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.io.OutputStream;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.sun.image.codec.jpeg.JPEGCodec;

import com.sun.image.codec.jpeg.JPEGEncodeParam;

import com.sun.image.codec.jpeg.JPEGImageEncoder;

publicclass CreateImageServlet extends HttpServlet {

publicvoid doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

//取消缓存，否则没有单击后更新不了图片

response.setHeader("cache-control", "no-cache");

response.setContentType("image/jpeg");

int width=50;

int height=30;

BufferedImage bi=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);

Graphics2D g=bi.createGraphics();

g.setBackground(Color.YELLOW);

g.clearRect(0,0,width, height);

g.setColor(Color.BLACK);

g.drawString(getRandomString(request), 5, 20);

g.dispose();

bi.flush();

//设定jpg格式解码

OutputStream outPut=response.getOutputStream();

JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(outPut);

JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bi);

param.setQuality(1.0f, false);

encoder.setJPEGEncodeParam(param);

try {

encoder.encode(bi);

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

System.out.println("image runed ...");

}

publicvoid doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

this.doGet(request, response);

}

//随机生成的四位数的验证码

private String getRandomString(HttpServletRequest request){

int ranNum=(int)(Math.random()*9000)+1000;

//放置进session

request.getSession().setAttribute("ranNum", ranNum+"");

return ranNum+"";

}

//生成执行注册或者登陆的JSP页面-----------------------------------

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>

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>

function changeImage(obj){

obj.src="servlet/CreateImageServlet";

}

function confDialog(obj){

if(confirm("if yes or no")){

obj.href="a.jsp";

}

function hrefuri(){

location.href="a.jsp";

}

</script>

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

<!--

-->

</head>

<body>

This is my JSP page. <br>

<form action="<%=request.getContextPath() %>/servlet/CheckLog" method="post">

</form>

</body>

</html>

//生成验证登陆的Servlet：------------------------------------------

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

publicclass CheckLog extends HttpServlet {

publicvoid doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

this.doPost(request, response);

}

publicvoid doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

//获取输入图片

String submitStr=request.getParameter("checkText");

//获取放置在session中的生成代码

String checkStr=request.getSession().getAttribute("ranNum").toString();

//验证

if(checkStr.equals(submitStr)){

System.out.println("Success!!!");

}else{

System.out.println("Failed!!!");

}

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