转载自：http://www.xrss.cn/Dev/JAVA/200792816836.Html

实现非常简单，例子主要有3个类，ImageContainer.java 在内存中保存动态走势图，ImageServlet.java 输出图片servlet，RandomValueThread.java模拟随机数据的线程。

为了要生成gif 图片 ，请先在http://www.fmsware.com/stuff/gif.zip 下载处理GIF图片的代码，解压之后可以发现有AnimatedGifEncoder.java, GifDecoder.java, ... 其中AnimatedGifEncoder.是用来生成GIF文件的

Gif图片比Jpeg 要小的多，另外动态走势图保存在内存中，不用生成图片文件的。

准备一张背景图片400×200大小，如下

ImageContainer.java

package com.web;

import java.awt.Color;

import java.awt.Graphics;

import java.awt.Image;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.IOException;

import java.util.LinkedList;

import java.util.List;

import javax.imageio.ImageIO;

public class ImageContainer {

public final static int MAX_LIST_SIZE = 100;

public final static int DEFAULT_WIDTH = 400;

public final static int DEFAULT_HEIGHT = 200;

public final static int DOT_WIDTH = 4;

public final static int DOT_HEIGHT = 2;

public final static String BACKGROUND_IMAGE = "/bg.gif";

private LinkedList valueList = new LinkedList();

private Image image = null;

private void loadImageFile() {

File file = new File(this.getClass().getResource(BACKGROUND_IMAGE)

.getFile());

try {

image = ImageIO.read(file);

} catch (IOException e) {

System.err.println("Can not load backgroud, reason:"

+ e.getMessage());

}

}

private ImageContainer() {

}

private static ImageContainer intance = new ImageContainer();

public static ImageContainer getInstance() {

return intance;

}

public synchronized List getList() {

return valueList;

}

public synchronized void pushValue(Integer value) {

if (valueList.size() >= MAX_LIST_SIZE) {

valueList.poll();

}

valueList.offer(value);

}

public BufferedImage draw() {

BufferedImage tag = new BufferedImage(DEFAULT_WIDTH, DEFAULT_HEIGHT,

BufferedImage.TYPE_INT_RGB);

if (image == null) {

loadImageFile();

}

if (image != null) {

int width = image.getWidth(null);

int height = image.getHeight(null);

tag.getGraphics().drawImage(image, 0, 0, width, height, null);

}

Graphics g = tag.getGraphics();

g.setColor(Color.GREEN);

List valueList = this.getList();

int x1 = 0, y1 = 0, x2 = 0, y2 = 0;

int size = valueList.size();

int offset = (MAX_LIST_SIZE - size) * DOT_WIDTH;

x1 = offset;

y1 = DEFAULT_HEIGHT-0;

for (int i = 0; i < size; i++) {

x2 = offset + i * DOT_WIDTH;

y2 = DEFAULT_HEIGHT-(Integer) valueList.get(i) * DOT_HEIGHT;

g.drawLine(x1, y1, x2, y2);

System.out.printf("drawLine[%d,%d,%d,%d]", x1, y1, x2, y2);

x1 = x2;

y1 = y2;

}

System.out.println();

return tag;

}

}

RandomValueThread.java

package com.web;

import java.util.Random;

public class RandomValueThread extends Thread {

private boolean isRunning = false;

public synchronized boolean isRunning() {

return isRunning;

}

public synchronized void setRunning(boolean isRunning) {

this.isRunning = isRunning;

}

@Override

public synchronized void start() {

isRunning = true;

super.start();

}

@Override

public void run() {

int v;

Random randomp = new Random();

while (isRunning) {

v = randomp.nextInt(100);

System.out.println("Put random value=" + v);

ImageContainer.getInstance().pushValue(v);

try {

Thread.sleep(1000);

} catch (InterruptedException e) {

}

}

}

}

ImageServlet.java

package com.web.servlet;

import giftool.AnimatedGifEncoder;

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.web.ImageContainer;

import com.web.RandomValueThread;

public class ImageServlet extends HttpServlet {

private static final String GIF = "image/gif";

private static final String JPG = "image/jpeg";

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType(GIF);

BufferedImage image = ImageContainer.getInstance().draw();

OutputStream out = response.getOutputStream();

// JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

// encoder.encode(image);

AnimatedGifEncoder encoder = new AnimatedGifEncoder();

encoder.setRepeat(0);

encoder.start(out);

encoder.addFrame(image);

encoder.finish();

out.close();

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doGet(request, response);

}

public void init() throws ServletException {

// Start random value thread

RandomValueThread thread = new RandomValueThread();

thread.setDaemon(true);

thread.start();

}

}

web.xml 加入

ImageServlet

com.web.servlet.ImageServlet

ImageServlet

/ImageServlet

demo.htm

Memory Copy Buffer Image

function refreshImage() ...{

document.getElementById("viewImg").src="ImageServlet?"+Math.random();

setTimeout(refreshImage,1000);

}

setTimeout(refreshImage,1000);

最终演示效果图:

posted on 2008-06-25 11:25 蒋家狂潮 阅读(1217) 评论(0)  编辑  收藏