加载index.jsp出现img标签两次请求servlet图片解决思路

加载index.jsp出现img标签两次请求servlet图片



<!-- index.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 'index.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">

<meta http-equiv="cache-control" content="no-cache">

<meta http-equiv="expires" content="0">

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

<meta http-equiv="description" content="This is my page">

<!--

	<link rel="stylesheet" type="text/css" href="styles.css">

	-->

<link rel="stylesheet" type="text/css" href="common.css">


<script type="text/javascript">

	function refresh(img) {

		//alert("aaaaaaa");

		img.src = img.src + "?" + new Date().getTime();

	}

</script>


</head>


<body class="center">

	<h3>欢迎来到宠物小屋</h3>


	<form id="form1" name="form" action="/javaWork/servlet/Pet">

		<table class="left">

			<tr>

				<td><b>宠物种类:</b></td>

				<td><select name="type" onchange="typeChanged()">

						<option value="dog">狗狗</option>

						<option value="penguin">企鹅</option>

				</select>

				</td>

			</tr>

			<tr>

				<td><b>宠物昵称:</b></td>

				<td><input type="text" name="name" /></td>

			</tr>

			<tr>

				<td><b>健康值:</b></td>

				<td><input type="text" name="health"><span class="red">(0~100)</span>

				</td>

			</tr>

			<tr>

				<td>验证码:</td>

				<td><input type="text" name="checkCode" /><img

					src="/javaWork/servlet/CheckImage?i=1" title="点击刷新"

					onclick="refresh(this)" style="cursor:pointer" />

				</td>

			</tr>

			<tr>

				<td class="center"><input type="submit" value="提交" /></td>

				<td class="center"><input type="reset" value="清空" /></td>

			</tr>

		</table>



	</form>

</body>

</html>



//Servlet: CheckImage.java


package cn.bdqb.t36;


import java.awt.Color;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.io.PrintWriter;


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 ImageHealth extends HttpServlet {


	public final int WIDTH = 100;

	public final int HEIGHT = 20;


	public void doGet(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		BufferedImage img = new BufferedImage(WIDTH, HEIGHT,

				BufferedImage.TYPE_INT_RGB);

		Graphics g = img.getGraphics();


		setSize(g);

		setWidth(g);

		drawRectangle(g);


		response.setDateHeader("expires", -1);

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

		response.setContentType("image/jpeg");

		ImageIO.write(img, "jpg", response.getOutputStream());


	}


	// 设置边框样式

	private void setSize(Graphics g) {


		g.setColor(Color.BLUE);

		g.fillRect(0, 0, WIDTH, HEIGHT);


	}


	// 设置边框线大小

	private void setWidth(Graphics g) {

		g.setColor(Color.WHITE);

		g.fillRect(2, 2, WIDTH - 4, HEIGHT - 4);

	}


	// 画出方块标示健康值

	private void drawRectangle(Graphics g) {

		g.setColor(Color.RED);

		int health = Common.dog.getHealth() / 10;

		int xP = 0;

		for (int i = 0; i < health; i++) {

			g.fillRect(xP, 20, WIDTH, HEIGHT);

			xP += 10;

		}

	}


	public void doPost(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		doGet(request, response);

	}


}