Hướng dẫn gọi phương thức từ xa với Java RMI

package org.o7planning.tutorial.rmi;

public class Constants {

   // Địa điểm Hà Nội
   public static final String LOCATION_HANOI = "HaNoi";    
   public static final String LOCATION_TOKYO = "Tokyo";
   public static final String LOCATION_CHICAGO = "Chicago";
   
   
   // Thời tiết mưa
   public static final String WEATHER_RAIN ="rain";
   
   // Thời tiết nắng.
   public static final String WEATHER_SUNNY ="sunny";

}

package org.o7planning.tutorial.rmi;

import java.io.Serializable;
import java.util.Date;

public class WeatherData implements Serializable {

   private static final long serialVersionUID = 1L;

   private Date date;
   private String location;
   private String weather;

   public WeatherData(Date date, String location, String weather) {
       this.date = date;
       this.location = location;
       this.weather = weather;
   }

   public Date getDate() {
       return date;
   }

   public void setDate(Date date) {
       this.date = date;
   }

   public String getLocation() {
       return location;
   }

   public void setLocation(String location) {
       this.location = location;
   }

   public String getWeather() {
       return weather;
   }

   public void setWeather(String weather) {
       this.weather = weather;
   }

}

package org.o7planning.tutorial.rmi;

import java.rmi.Remote;
import java.rmi.RemoteException;
import java.util.Date;



public interface WeatherService extends Remote {

 // Method lấy về đối tượng thông tin thời tiết.
 // Tham số truyền vào ngày & địa điểm.
 public WeatherData getWeather(Date date, String location)
         throws RemoteException;
}

package org.o7planning.tutorial.rmi.server;

import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.util.Calendar;
import java.util.Date;

import org.o7planning.tutorial.rmi.Constants;
import org.o7planning.tutorial.rmi.WeatherData;
import org.o7planning.tutorial.rmi.WeatherService;

public class WeatherServiceImpl extends UnicastRemoteObject implements
      WeatherService {
  private static final long serialVersionUID = 1L;

  public WeatherServiceImpl() throws RemoteException {
      super();
  }

  @Override
  public synchronized WeatherData getWeather(Date date, String location)
          throws RemoteException {
      Calendar c = Calendar.getInstance();
      c.setTime(date);

      int dayOfWeek = c.get(Calendar.DAY_OF_WEEK);

      // Sunday, Monday
      if (dayOfWeek == 1 || dayOfWeek == 2) {
          if (location.equals(Constants.LOCATION_CHICAGO)) {
              // Rain
              return new WeatherData(date, location, Constants.WEATHER_RAIN);
          } else if (location.equals(Constants.LOCATION_HANOI)) {
              // Sunny
              return new WeatherData(date, location, Constants.WEATHER_SUNNY);
          } else if (location.equals(Constants.LOCATION_TOKYO)) {
              // Sunny
              return new WeatherData(date, location, Constants.WEATHER_SUNNY);
          }
          return new WeatherData(date, location, Constants.WEATHER_SUNNY);
      } else {
          return new WeatherData(date, location, Constants.WEATHER_SUNNY);
      }

  }
}

package org.o7planning.tutorial.rmi.client;

import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.util.Date;

import org.o7planning.tutorial.rmi.Constants;
import org.o7planning.tutorial.rmi.WeatherData;
import org.o7planning.tutorial.rmi.WeatherService;

public class Client {

   // Host or IP of Server
   private static final String HOST = "localhost";
   private static final int PORT = 1099;
   private static Registry registry;

   public static void main(String[] args) throws Exception {

       // Search the registry in the specific Host, Port.
       registry = LocateRegistry.getRegistry(HOST, PORT);

       // Lookup WeatherService in the Registry.
       WeatherService service = (WeatherService) registry
               .lookup(WeatherService.class.getSimpleName());

       Date today = new Date();

       // Get Chicago weather info:
       WeatherData chicagoWeather = service.getWeather(today,
               Constants.LOCATION_CHICAGO);

       System.out.println("Chicago weather today: "
               + chicagoWeather.getWeather());
       
       // Get Hanoi weather info:
       WeatherData hanoiWeather = service.getWeather(today,
               Constants.LOCATION_HANOI);

       System.out.println("Hanoi weather today: " + hanoiWeather.getWeather());

   }
}

package org.o7planning.tutorial.rmi.server;

import java.rmi.AlreadyBoundException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;

import org.o7planning.tutorial.rmi.WeatherService;

public class Server {
   private static final int PORT = 1099;
   private static Registry registry;

   public static void startRegistry() throws RemoteException {

       // Tạo một bộ đăng ký (Registry) tại Server.
       registry =  LocateRegistry.createRegistry(PORT);
   }

   public static void registerObject(String name, Remote remoteObj)
           throws RemoteException, AlreadyBoundException {
       // Đăng ký đối tượng vào bộ đăng ký.
       // Nó được gắn với cái tên nào đó.
       // Client sẽ tìm trên bộ đăng ký với tên này để có thể gọi đối tượng.


       registry.bind(name, remoteObj);
       System.out.println("Registered: " + name + " -> "
               + remoteObj.getClass().getName() + "[" + remoteObj + "]");
   }

   public static void main(String[] args) throws Exception {
       System.out.println("Server starting...");
       startRegistry();
       registerObject(WeatherService.class.getSimpleName(), new WeatherServiceImpl());

       // Server đã được start, và đang lắng nghe các request từ Client.
       System.out.println("Server started!");
   }
}