The technical principle of the ‘simple RMI’ framework in the Java class library
The technical principle of the ‘simple RMI’ framework in the Java class library
Simple RMI (Remote Method Invocation) is a remote communication framework in the Java language that allows method calls between different Java processes in distributed systems.It realizes the function of remote communication and method calls based on some core classes and interfaces in the Java library.The technical principles of the simple RMI framework will be introduced below.
1. Remote interface definition
The first step of the simple RMI framework is to define remote interfaces.Remote interfaces are a set of abstract methods that declare the services that remote objects can provide.The remote interface must expand the java.rmi.remote interface, and the method of each declaration must be thrown out of Java.rmi.remoteException.The following is a simple remote interface example:
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface MyRemoteInterface extends Remote {
public String sayHello() throws RemoteException;
}
2. Realm of remote objects
Next, remote interfaces need to be achieved to create specific remote objects.These remote objects provide services defined in remote interfaces.Remote objects need to expand java.rmi.server.unicastremoteObject class and implement methods in remote interfaces.The following is a simple remote object example:
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
public class MyRemoteObject extends UnicastRemoteObject implements MyRemoteInterface {
public MyRemoteObject() throws RemoteException {
super();
}
public String sayHello() throws RemoteException {
return "Hello, world!";
}
}
3. Registration of remote objects
Before remote communication, the remote object needs to be registered in the RMI registry.The RMI registry is a server -side component used to store remote objects.The client can find and obtain a reference to the remote object through the RMI registry.The following is an example of a simple remote object registration:
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
public class Server {
public static void main(String[] args) {
try {
MyRemoteInterface remoteObject = new MyRemoteObject();
Registry registry = LocateRegistry.createRegistry(1099);
registry.bind("MyRemoteObject", remoteObject);
System.out.println("Remote object registered.");
} catch (Exception e) {
e.printStackTrace();
}
}
}
4. Remote object access
The client can find and obtain a reference to the remote object through the RMI registry, and then use this reference to call the remote object.The following is a simple remote object access example:
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
public class Client {
public static void main(String[] args) {
try {
Registry registry = LocateRegistry.getRegistry("localhost", 1099);
MyRemoteInterface remoteObject = (MyRemoteInterface) registry.lookup("MyRemoteObject");
String result = remoteObject.sayHello();
System.out.println("Remote method result: " + result);
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above code, the client uses the `localEgistry.getRegistry` method to obtain the reference to the RMI registry, and then use the reference to call the` logup` method to get the reference to the remote object.Finally, the client uses the method of remote objects to call the remote object obtained by the client.
The technical principle of the simple RMI framework is based on the Java remote communication -related class and interface implementation of the Java library.It allows remote methods to call in a distributed system and simplify the process of remote communication.+
