helloapplet.java

java网络编程 包含全书所有代码编程以及实例

package helloinapplet;

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.rmi.*;

public class helloApplet extends Applet {
  boolean isStandalone = false;
  String message = "blank";
  //"obj" is the identifier that we'll use to refer
  //to the remote object that implements the "Hello"
  //interface
  private Button button1 = new Button();
  private Label label1 = new Label();  //Get a parameter value
  public String getParameter(String key, String def) {
    return isStandalone ? System.getProperty(key, def) :
      (getParameter(key) != null ? getParameter(key) : def);
  }

  //Construct the applet
  public helloApplet() {
  }
  //Initialize the applet
  public void init() {
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  //Component initialization
  private void jbInit() throws Exception {
    button1.setLabel("Click me");                           //设计布局
    button1.setBounds(new Rectangle(120, 143, 91, 29));
    button1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        button1_actionPerformed(e);
      }
    });
    this.setLayout(null);
    label1.setBounds(new Rectangle(105, 90, 395, 31));
    this.add(button1, null);
    this.add(label1, null);
  }

  public void paint(Graphics g){
    g.drawString("", 25, 50);
    }

  //Get Applet information
  public String getAppletInfo() {
    return "Applet Information";
  }
  //Get parameter info
  public String[][] getParameterInfo() {
    return null;
  }

  void button1_actionPerformed(ActionEvent e) {
    try {
      label1.setText("正在连接RMI主机...");
      hello obj = (hello)Naming.lookup("rmi://127.0.0.1/HelloWorld");   //寻找RMI主机的相应服务
      message = obj.sayHello();              //调用远程函数
      label1.setText(message);               //显示结果
    }
    catch (Exception e1)
    {
      label1.setText("Error: " + e1);        //捕捉异常情况
    }
  }
}