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J2EE开发---验证码（一）

2016-07-14 10:18 183 查看

ImageServlet.java

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

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

public class ImageServlet extends HttpServlet{

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {

BufferedImage bi = new BufferedImage(68,22,BufferedImage.TYPE_INT_RGB);
Graphics g = bi.getGraphics();
Color c = new Color(200,150,255);
g.setColor(c);
g.fillRect(0, 0, 68, 22);

char[] ch = "ABCDEFGHIGKLMNOPQRSTUVWXYZ".toCharArray();

//使用随机数，来随机的产生验证码
Random r = new Random();
int len = ch.length,index;

StringBuffer sb = new StringBuffer();
for(int i=0; i<4; i++){
index = r.nextInt(len);
g.setColor(new Color(r.nextInt(88),r.nextInt(188),r.nextInt(255)));
g.drawString(ch[index]+"",(i*15)+3,18);
sb.append(ch[index]);

}

//将产生的验证码，存放至session中，以便在后台进行对比验证
req.getSession().setAttribute("piccode", sb.toString());
ImageIO.write(bi, "JPG", resp.getOutputStream());

}
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>checkCode</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>

<servlet>
<servlet-name>ImageServlet</servlet-name>
<servlet-class>com.muke.ImageServlet</servlet-class>
</servlet>

<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.muke.LoginServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>ImageServlet</servlet-name>
<url-pattern>/servlet/ImageServlet</url-pattern>
</servlet-mapping>

<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/servlet/LoginServlet</url-pattern>
</servlet-mapping>

</web-app>

index.jsp

<%@ page language="java" contentType="text/html; charset=GBK"
pageEncoding="GBK"%>

<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+"";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>Insert title here</title>

<script type="text/javascript">
function reloadCode(){

//给页面传递一个时间参数，时间时刻在变化，所以每一次点击刷新都被浏览器认为是一次新的请求，即产生新的验证码

//如果不添加时间参数，因为页面有缓存,  不会使页面刷新
var time = new Date().getTime();
document.getElementById("imagecode").src="<%=request.getContextPath()%>/servlet/ImageServlet?d="+time;
}

</script>

</head>
<body>
<form action="<%=request.getContextPath()%>/servlet/LoginServlet" method="get">
验证码：<input type="text" name="checkcode"/>
<img alt="验证码" id="imagecode" src="<%=request.getContextPath()%>/servlet/ImageServlet"/>
<a href="javascript:reloadCode();">看不清楚</a><br>
<input type="submit" value="提交"/>
</form>
</body>
</html>

LoginServlet.java

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;

public class LoginServlet extends HttpServlet{

/**
*
*/
private static final long serialVersionUID = 1L;

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
resp.setContentType("text/html; charset=GBK");

//获取保存在session中的系统生成的验证码
String piccode = (String) req.getSession().getAttribute("piccode");
//获取页面输入的验证码
String checkcode = req.getParameter("checkcode");
//大小写忽略
checkcode = checkcode.toUpperCase();

PrintWriter pw = resp.getWriter();
if(piccode.equals(checkcode)){
pw.println("验证成功；");
}else{
pw.println("验证出错");
}

pw.flush();
pw.close();

}

}

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