Servlet doget（）方法实现随机图片的生成

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Servlet doget（）方法实现随机图片的生成

java代码：

package com.sunbing;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
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.JPEGImageEncoder;

/**
 * Servlet implementation class TestServlet
 */
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
	//随机字符字典
	public static final char[] chars = {'1','2','3','4','5','6','7','8','9','0'};
	//产生随机数
	public static Random random = new Random();
	public static String getRandomString(){
		StringBuffer buffer = new StringBuffer();
		for(int i = 0; i<5; i++)
		{
			buffer.append(chars[random.nextInt(chars.length)]);
		}
		return buffer.toString();
	}
	/*获取随机的颜色*/
	public static Color getRandomColor()
	{
		return new Color(random.nextInt(255), random.nextInt(255),random.nextInt(255));
	}
	/*返回某颜色的反色*/
	public static Color getReverseColor(Color c)
	{
		return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue());
	}
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		/*设置输出类型*/
		response.setContentType("image/jpeg");
		/*随机字符串*/
		String randomString = getRandomString();
		/*将randomString放到session中*/
		request.getSession(true).setAttribute("randomString", randomString);
		/*设置图片的宽高*/
		int width = 100;
		int height = 30;
		/*随机颜色用于背景颜色，反色用于前景颜色*/
		Color color = getRandomColor();
		Color reverse = getReverseColor(color);
		BufferedImage bi = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
		Graphics2D g = bi.createGraphics();
		g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 16));
		g.setColor(color);
		g.fillRect(0, 0, width, height);
		g.setColor(reverse);
		g.drawString(randomString, 18, 20);
		for(int i = 0, n = random.nextInt(100); i <n; i++)
		{
			g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);
		}
		ServletOutputStream out = response.getOutputStream();
		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
		encoder.encode(bi);
		out.close();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

}

XML配置

<?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>IdentityServlet</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>TestServlet</servlet-name>
		<servlet-class>com.sunbing.TestServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>TestServlet</servlet-name>
		<url-pattern>/servlet/TestServlet</url-pattern>
	</servlet-mapping>
</web-app>

前台html展示

<!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>随机图片</title>
</head>
<script>
function reloadImage()
{
	document.getElementById('btn').disable = true;
	document.getElementById('identity').src = 'servlet/TestServlet?ts=' + new Date().getTime();
}
</script>
<body>
<img src="servlet/TestServlet" id = "identity" onload="btn.disable = false;"/>
<input type=button value="换个图片" onclick="reloadImage()" id = "btn"/>

</body>
</html>