Flex Image加载Servlet图像流处理

  Image控件是Flex加载、显示图像的一个控件，当然其也可以加载SWF文件。Image加载图像有3种方式：

       1）使用@Embed，该种方式加图像数据直接编译到swf文件中去，加载速度最快，但是其编译后的swf文件较大；

    2）使用应用的相对路径

    如tomcat下有个应用，flex-demo，假设flex客户端程序是发布到flex-demo的web目录下，若在web目录下有一个/statics/image/home.png文件，则image控件若要加载该文件只要设置其source如下即可：

    Source = “statics/image/home.png”，flex application在运行时会自动去服务器加载该文件。

    3）使用servlet

    使用servlet进行图像加载需要做2个事情：servlet编写和image的source设置为该servlet的mapping url。

    Servlet编写：

    只要该servlet继承httpservlet即可，要注意的就是response需要输出图片文件流，代码如下：

package com.servlet;

 

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.OutputStream;

 

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

 

/**

 *

 * <p>Description:image加载图片Servlet</p>

 * @author Marcus

 * @version $Id: CaptureShowServlet.java,v 0.1 2010-9-27 上午08:19:09 Exp $

 */

public class CaptureShowServlet extends HttpServlet{

       /**

        * Comment for <code>serialVersionUID</code>

        */

       private static final long serialVersionUID = 1L;

 

       private String picFolder = "d:/pictures";

       public void destroy()

       { 

              super.destroy();

       }

      

       public void init(ServletConfig config) throws ServletException{

              super.init(config);

       }

      

       @Override

       public void doGet(HttpServletRequest request, HttpServletResponse response)

              throws ServletException, IOException{

        String fileName = request.getParameter("fileName");

        String mimeType = "image/gif";   

        // Set content type

        response.setContentType(mimeType);

   

        // Set content size

        File file = new File(picFolder + File.separator + fileName);

        response.setContentLength((int)file.length());

        // Open the file and output streams

        FileInputStream in = new FileInputStream(file);

        OutputStream out = response.getOutputStream();

        // Copy the contents of the file to the output stream

        byte[] buf = new byte[1024];

        int count = 0;

        while ((count = in.read(buf)) >= 0) {

            out.write(buf, 0, count);

        }

        in.close();

        out.close();

       }

      

       public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException  

       { 

              //processRequest(request, response);

       }

}

       Image的source指定：

       假设servlet的访问地址为http://localhost:8080/servlet/CaptureShowServlet,加载的图片文件名为pic01.jpg，则只要如下设置image的source即可：

       Source = “http://localhost:8080/servlet/CaptureShowServlet?fileName=pic01.jpg”