Applet与Servlet之间的通信与交互

                   Applet与Servlet之间的通信与交互
Applet的优势在于可以操作客户端的资源,一般要操作客户端的资源---如上传文件,调用客户端的应用程序,调用客户端的打印机实现本地打印等,一般都是用Applet程序实现的,并将其嵌入到网页中,通过Applet将本地资源转换成流,然后连接后台服务器的SERVLET,并达到与之交互,将客户端的资源上传到服务器中.如我最近在项目中遇到的的一个问题:需要将客户端的桌面上的文件上传到服务器上的特定文件中.
Applet小程序
import java.applet.Applet;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import javax.swing.filechooser.FileSystemView;


public class DesktopReadJpg extends Applet{
   
    /**
     * 初始化Applet
     */
    public void init()
    {
        FileSystemView fsv = FileSystemView.getFileSystemView();
        File vFile = fsv.getHomeDirectory();
        String path = vFile.getPath();
       
        String picUrl = getParameter("PICURL");
        try{
            //URL url1 = new URL("http://localhost:8080/vmis/appletServlet");
            URL url1 = new URL(picUrl);
            HttpURLConnection conn = (HttpURLConnection) url1.openConnection();
            conn.setRequestMethod("POST");
            conn.setAllowUserInteraction(true);
            conn.setDoInput(true);
            conn.setDoOutput(true);
            conn.setUseCaches(true);
            conn.setRequestProperty("Content-Type", "application/octet-stream");
           
           
            File jpgFile = new File(path+"\\ZP.JPG");
            if(jpgFile.isFile()){
                // 建立文件的输入流
                FileInputStream fileInputStream = null;
                fileInputStream = new FileInputStream(jpgFile);
                BufferedInputStream bis=new BufferedInputStream(fileInputStream);
                OutputStream os = conn.getOutputStream();
                BufferedOutputStream bos=new BufferedOutputStream(os);
                int len =0;
                byte[] bty=new byte[4096];
                while((len=bis.read(bty,0,4096))!=-1){
                    bos.write(bty, 0, len);
                    bos.flush();
                   
                }
                bos.close();
                bis.close();
                System.out.println(conn.getContentType() + ": "
                        + conn.getResponseCode());
            }
        }catch(Exception e){
            e.printStackTrace();
           
        }
      
    }
}

其中System.out.println(conn.getContentType() + ": "+
conn.getResponseCode());,这句必须加上才能够连接上服务器上的Servlet完成上传工作
与之交互的Servlet程序:
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.maslong.pub.Constants;


public class AppletServlet extends HttpServlet{
   
    public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws IOException {
            InputStream in = request.getInputStream();       
           //System.out.print(request.getParameter("username"));
            File f = new File(Constants.PHOTODIR+"Head.JPG");
            FileOutputStream fos = new FileOutputStream(f);

            byte[] b = new byte[1024 * 1024];
            int bytes, sumBytes = 0;

            while (true) {
                bytes = in.read(b);
                if (bytes <= 0)
                    break;
                sumBytes += bytes;
                fos.write(b, 0, bytes);
            }
            fos.close();
            in.close();         
    }
   
    public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws IOException {

        doGet(request, response);
    }
}