Servlet傳送物件給Applet使用 (轉)

Servlet傳送物件給Applet使用 (轉)[@more@]

 前日,一位朋友與我談論與Applet共享的問題,現發表出來與大家分享,文中瑕癖
之處甚多,望各位指教.
 朋友談論的需求是這樣的:他想透過頁面上一個Applet呼叫一個Servlet,而從Servlet產生
一個Java物件再傳給另外一個Applet,怎麼樣讓Servlet實時地把物件傳給Applet這是一個問題,有一個方
案是採用(JavaMessageService),在我以後的文章中會有敘述的.這裡我給大家展示一個簡單的實現,那
就是讓Applet主動訪問Servlet,讓Servlet返回Java物件.下面給出全部程式碼和,其中Applet部分涵蓋
了與Applet的互相,對於該部分不感興趣的朋友可以復略.

第一步,編寫需要傳遞的物件類
/**
 * Class Person just a demo for translate this class to client
 * @author: rookie
 * @datetime: 2002-7-26
 */
package exapplet;
import java.io.*;
public class Person implements Serializable {//必須實現Serializable介面才能序列化
 private String m_Name;
 private int m_Age;
 public Person() {
 this("",0);
 }
 public Person(String name,int age) {
 this.m_Name = name;
 this.m_Age = age;
 }
 public String getName() {
 return m_Name;
 }
 public int getAge() {
 return m_Age;
 }
 //Serializable介面中宣告的方法
 private void write(java.io.ObjectOutputStream out) 
  throws IOException {
 out.defaultWriteObject();
 }
 //Serializable介面中宣告的方法 
 private void readObject(java.io.ObjectInputStream in)
  throws IOException, ClassNotFoundException {
 in.defaultReadObject();
 } 
 public static void main(String[] args) {
 try {
 Person p = new Person("Liaoyuan",25);
 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(new File("test.obj")));
 oos.writeObject(p);
 oos.close();
 ObjectInputStream ois = new ObjectInputStream (new FileInputStream(new File("test.obj")));
 Person q = (Person)ois.readObject();
 ois.close();
 System.out.println(q.getName());
 System.out.println(q.getAge());
 } catch(Exception exp) {
 exp.printStackTrace();
 }
 }
}

第二步,實現Servlet
package exapplet;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet extends HttpServlet 
{
 public void doGet(HttpServletRequest req,HttpServletResponse res)
 throws ServletException,IOException
 {
 String fPath = "H:XSchoolWorkingRoomexappletsrcjava.obj";
 
 String act = req.getParameter("Action");
 if ( act.equals("UpdateObject") ) {
 //建立JavaObject
 Person p = new Person("Liaoyuan",26);
 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(new File(fPath)));
 oos.writeObject(p);
 oos.close();
 DataOutputStream dos = new DataOutputStream(res.getOutputStream());
 dos.writeBytes("Server Java Object Updated OK!");
 dos.close();
 } else if ( act.equals("GetObject") ) {
 //傳回物件給Applet
 res.setContentType("application/octet-stream");
 Person p;
 ObjectInputStream ois = new ObjectInputStream(new FileInputStream(new File(fPath)));
 try {
 p  = (Person)ois.readObject();
 } catch (ClassNotFoundException e) {
 p = new Person();
 }
 ois.close();
 
 ObjectOutputStream o= new ObjectOutputStream(res.getOutputStream());
 oos.writeObject(p);
 oos.close();
 }
 }
 public String getServletInfo()
 {
 return "A simple Servlet!";
 }
}

第三步,實現呼叫Servlet更新物件的Applet
package exapplet;
import java.awt.*;
import java.applet.*;
import java.io.*;
import java.*;
import .javascript.*;
public class MyApplet extends java.applet.Applet
{
 public void init()
 {
 }
 public void paint(Graphics g)
 {}
 //This method will be call in html
 public void invoke() {
 try {
 URL url = new URL("");
 URLConnection urlcon = url.openConnection();
 urlcon.connect();
 
 DataInputStream dis=new DataInputStream(urlcon.getInputStream());
 String txt = dis.readLine();
 dis.close();
 
 String[] info = new String[]{txt};
 JSObject.getWindow(this).call("alert",info);
 } catch (Exception e) {
 }
 }
}

第四步,實現提取物件的Applet
package exapplet;
import java.awt.*;
import java.applet.*;
import java.io.*;
import java.net.*;
import netscape.javascript.*;
public class MyAppletB extends java.applet.Applet
{
 public void init()
 {
 }
 public void paint(Graphics g)
 {}
 //This method will be call in html
 public void invoke() {
 try {
 URL url = new URL("");
 URLConnection urlcon = url.openConnection();
 urlcon.connect();
 ObjectInputStream ois=new ObjectInputStream(urlcon.getInputStream());
 Person p = (Person)ois.readObject();
 ois.close();
 String[] info = new String[]{"Person Infonn-Name: "+p.getName()+"n-Age : "+p.getAge()};
 JSObject.getWindow(this).call("alert",info);
 } catch (Exception e) {
 }
 }
}
第五步,配製Server(我用的是4.0)
複製編譯後的MyServlet.class到相應目錄下,
編輯對應的web.,確保下面的內容正確

">

 
  PostToApplet
  exapplet.MyServlet
  
 
  
  PostToApplet
  
  
  /exapplet/PostToApplet
  
  

第六步,編寫html檔案
呼叫更新的html





Hello This is a Test!






提取物件的html





Hello This is a Test!

中間有錯誤的地方請指教,zlyperson@163.net