零教程

在上一章中，我们创建了一个RMI应用程序的示例。 在本章中，我们将介绍如何创建一个客户端调用显示GUI窗口(基于JavaFX)的RMI应用程序。

定义远程接口

在这里，首先定义一个名称为Hello的远程接口，此接口中有一个名称为animation()的方法。

import java.rmi.Remote 
import java.rmi.RemoteException  

// Creating Remote interface for our application 
public interface Hello extends Remote { 
   void animation() throws RemoteException 
}

开发实现类

在本应用程序的Implementation类(远程对象)中，将创建一个使用JavaFX显示GUI内容的窗口。创建一个Java源代码文件：FxSample.java，其代码如下所示 -

import javafx.animation.RotateTransition  
import javafx.application.Application  
import javafx.event.EventHandler   

import javafx.scene.Group  
import javafx.scene.PerspectiveCamera  
import javafx.scene.Scene  
import javafx.scene.control.TextField  
import javafx.scene.input.KeyEvent  
import javafx.scene.paint.Color  
import javafx.scene.paint.PhongMaterial 

import javafx.scene.shape.Box  
import javafx.scene.text.Font  
import javafx.scene.text.FontWeight
import javafx.scene.text.Text   
import javafx.scene.transform.Rotate  

import javafx.stage.Stage  
import javafx.util.Duration  

// Implementing the remote interface 
public class FxSample extends Application implements Hello {  
   @Override  
   public void start(Stage stage) { 
      // Drawing a Box  
      Box box = new Box()  

      // Setting the properties of the Box  
      box.setWidth(150.0)  
      box.setHeight(150.0)    
      box.setDepth(100.0)  

      // Setting the position of the box  
      box.setTranslateX(350)   
      box.setTranslateY(150)  
      box.setTranslateZ(50)  

      // Setting the text  
      Text text = new Text(
         "Type any letter to rotate the box, and click on the box to stop the rotation")

      // Setting the font of the text  
      text.setFont(Font.font(null, FontWeight.BOLD, 15))      

      // Setting the color of the text  
      text.setFill(Color.CRIMSON)  

      // Setting the position of the text  
      text.setX(20)  
      text.setY(50) 

      // Setting the material of the box  
      PhongMaterial material = new PhongMaterial()   
      material.setDiffuseColor(Color.DARKSLATEBLUE)   

      // Setting the diffuse color material to box  
      box.setMaterial(material)        

      // Setting the rotation animation to the box     
      RotateTransition rotateTransition = new RotateTransition()  

      // Setting the duration for the transition  
      rotateTransition.setDuration(Duration.millis(1000))  

      // Setting the node for the transition  
      rotateTransition.setNode(box)        

      // Setting the axis of the rotation  
      rotateTransition.setAxis(Rotate.Y_AXIS)  

      // Setting the angle of the rotation 
      rotateTransition.setByAngle(360)  

      // Setting the cycle count for the transition  
      rotateTransition.setCycleCount(50)  

      // Setting auto reverse value to false  
      rotateTransition.setAutoReverse(false)   

      // Creating a text filed  
      TextField textField = new TextField()    

      // Setting the position of the text field  
      textField.setLayoutX(50)  
      textField.setLayoutY(100)  

      // Handling the key typed event  
      EventHandler<KeyEvent> eventHandlerTextField = new EventHandler<KeyEvent>() {  
         @Override  
         public void handle(KeyEvent event) {  
            // Playing the animation  
            rotateTransition.play()  
         }            
      }               

      // Adding an event handler to the text feld  
      textField.addEventHandler(KeyEvent.KEY_TYPED, eventHandlerTextField)  

      // Handling the mouse clicked event(on box)  
      EventHandler<javafx.scene.input.MouseEvent> eventHandlerBox =  
         new EventHandler<javafx.scene.input.MouseEvent>() {  
         @Override  
         public void handle(javafx.scene.input.MouseEvent e) {  
            rotateTransition.stop()   
         }  
      }  

      // Adding the event handler to the box   
      box.addEventHandler(javafx.scene.input.MouseEvent.MOUSE_CLICKED, eventHandlerBox) 

      // Creating a Group object 
      Group root = new Group(box, textField, text)  

      // Creating a scene object  
      Scene scene = new Scene(root, 600, 300)       

      // Setting camera  
      PerspectiveCamera camera = new PerspectiveCamera(false)  
      camera.setTranslateX(0)  
      camera.setTranslateY(0)  
      camera.setTranslateZ(0)  
      scene.setCamera(camera)   

      // Setting title to the Stage
      stage.setTitle("Event Handlers Example")  

      // Adding scene to the stage  
      stage.setScene(scene)  

      // Displaying the contents of the stage  
      stage.show()  
   }  

   // Implementing the interface method 
   public void animation() {  
      launch()  
   }  
}

服务器程序

RMI服务器程序应实现远程接口或扩展实现类。 在这里，应该创建一个远程对象并将其绑定到RMIregistry。

以下是本应用程序的服务器程序。在这里，我们将扩展上述创建的类，创建一个远程对象，并使用绑定名称：hello 将其注册到RMI注册表。创建一个Java源代码文件：Server.java，其代码如下所示 -

import java.rmi.registry.Registry 
import java.rmi.registry.LocateRegistry 
import java.rmi.RemoteException 
import java.rmi.server.UnicastRemoteObject 

public class Server extends FxSample { 
   public Server() {} 
   public static void main(String args[]) { 
      try { 
         // Instantiating the implementation class 
         FxSample obj = new FxSample()

         // Exporting the object of implementation class  
         // (here we are exporting the remote object to the stub) 
         Hello stub = (Hello) UnicastRemoteObject.exportObject(obj, 0)  

         // Binding the remote object (stub) in the registry 
         Registry registry = LocateRegistry.getRegistry() 

         registry.bind("Hello", stub)  
         System.err.println("Server ready") 
      } catch (Exception e) { 
         System.err.println("Server exception: " + e.toString()) 
         e.printStackTrace() 
      } 
   } 
}

客户端程序

以下是本应用程序的客户端程序。 在这里，我们提取远程对象并调用其animation()方法。创建一个Java源代码文件：Client.java，其代码如下所示 -

import java.rmi.registry.LocateRegistry 
import java.rmi.registry.Registry  

public class Client { 
   private Client() {} 
   public static void main(String[] args) {  
      try { 
         // Getting the registry 
         Registry registry = LocateRegistry.getRegistry(null) 

         // Looking up the registry for the remote object 
         Hello stub = (Hello) registry.lookup("Hello") 

         // Calling the remote method using the obtained object 
         stub.animation() 

         System.out.println("Remote method invoked") 
      } catch (Exception e) {
         System.err.println("Client exception: " + e.toString()) 
         e.printStackTrace() 
      } 
   } 
}

运行示例的步骤

以下是运行RMI示例的步骤。

第一步 - 打开存储所有程序的文件夹，并编译所有Java文件，如下所示。

F:\worksp\java_rmi\java-gui>javac *.java
F:\worksp\java_rmi\java-gui>

第二步 - 使用以下命令启动rmi注册表。

start rmiregistry

这将在单独的窗口中启动一个rmi注册表，如下所示。

第三步 - 运行服务器类文件，如下所示。

F:\worksp\java_rmi\java-gui>java Server
Server ready

第四步 - 运行客户端类文件，如下所示。

F:\worksp\java_rmi\java-gui> java Client

验证调用结果 - 当启动客户端以后，将在服务器中看到启动一个图形界面，如下所示 -