源自：2-2 验证码的代码实现
验证码出不来
<%@ page language="java" contentType="text/html; charset=utf-8"%>
<!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=utf-8">
<title>checkCode</title>
<script type="text/javascript">
function reloadCode(){
var time = new Date().getTime();
document.getElementById("imagecode").src="<%request.getContextPath();%>/yanzheng/ImageServlet?d="+time;
}
</script>
</head>
<body>
验证码：<input type="text" name="checkcode"/>
<img alt="验证码" id="imagecode" src="<%request.getContextPath();%>/yanzheng/ImageServlet" />
<a href="javascript:reloadCode();">看不清楚</a><br>
</body>
</html>
package com.imooc.yanzheng;
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.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class ImageServlet
*/
@WebServlet(name="ImageServlet",urlPatterns={"/yanzheng/ImageServlet"})
public class ImageServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ImageServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
public void doGet(HttpServletRequest request, HttpServletResponse response) {
BufferedImage bi = new BufferedImage(66,22,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 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456798".toCharArray();
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]);
}
request.getSession().setAttribute("piccode", sb.toString());
try {
ImageIO.write(bi, "JPG", response.getOutputStream());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
提问者：大咪
2016-08-03 08:17
个回答
-
- 丫丫小小笑
- 2016-08-03 10:11:26
这里路径写错了吧，首先<% 后边缺少一个等号，其次访问路径好像也不太对，建议你看一下你点击获取的时候路径的变化以及报错信息。
-
- 丫丫小小笑
- 2016-08-04 10:36:31
不是的，jsp表达式使用的就是<%= %>这样的方式，你应该是看错了。
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
path是获取的根目录，你也可以写<%=path>/......路径/.