Why should I use RMI?
In this project, for the communication between the client and the server, think a lot of ways, because do is rich client application, the final technology selected in the RMI and Java-sockets two, which RMI flexibility is not high, both client and server must be written Java, but the use of more convenient , Java-sockets, although more flexible, but need to specify their own server-side and client communication protocol. More trouble, after weighing, and ultimately choose RMI to do server-client communication
File Upload problem
In the process of using Java-rmi, you will inevitably encounter a file upload problem, because in the RMI can not transfer file flow (such as the RMI method parameters can not be fileinputstream and so on), then we have to choose a compromise approach, is to read the file in a byte array first, then pass the byte array as a parameter into the RMI method, and then restore the byte array to outputstream on the server side, so that the file can be transferred via RMI FileInputStream
This is also a disadvantage, that is, can not test the accuracy of the data transmitted over.
Here's an example to explain
Fileclient
Copy Code code as follows:
Package rmiupload;
Import Java.io.BufferedInputStream;
Import Java.io.File;
Import Java.io.FileInputStream;
Import java.io.FileNotFoundException;
Import java.io.IOException;
Import java.net.MalformedURLException;
Import java.rmi.Naming;
Import java.rmi.NotBoundException;
Import java.rmi.RemoteException;
public class Fileclient {
Public Fileclient () {
TODO auto-generated Constructor stub
}
public static void Main (string[] args) {
try {
Filedataservice Filedataservice = (filedataservice) naming.lookup ("Rmi://localhost:9001/filedataservice");
Filedataservice.upload ("/users/neverdie/documents/test.mp4", New Fileclient (). Filetobyte ("/Users/NeverDie/Music/ Test.mp4 "));
catch (Malformedurlexception | RemoteException | Notboundexception e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}
This method is more important by using this method to convert a file named filename to a byte array.
Private byte[] Filetobyte (String filename) {
Byte[] B = null;
try {
File File = new file (filename);
b = new byte[(int) file.length ()];
Bufferedinputstream is = new Bufferedinputstream (new FileInputStream (file));
Is.read (b);
catch (FileNotFoundException e) {
TODO auto-generated Catch block
E.printstacktrace ();
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
return b;
}
}
Filedataservice
Package rmiupload;
Import Java.net.URL;
Import Java.rmi.Remote;
Import java.rmi.RemoteException;
Public interface Filedataservice extends remote{
The filename here should be the address of the file stored on the server side
public void upload (String filename, byte[] file) throws RemoteException;
}
Filedataservice_imp
Copy Code code as follows:
Package rmiupload;
Import Java.io.BufferedOutputStream;
Import Java.io.File;
Import java.io.FileNotFoundException;
Import Java.io.FileOutputStream;
Import java.io.IOException;
Import Java.net.URL;
Import java.rmi.RemoteException;
Import Java.rmi.server.RMIClientSocketFactory;
Import Java.rmi.server.RMIServerSocketFactory;
Import Java.rmi.server.UnicastRemoteObject;
public class Filedataservice_imp extends UnicastRemoteObject implements filedataservice{
Public Filedataservice_imp () throws RemoteException {
}
@Override
public void upload (String filename, byte[] filecontent) throws remoteexception{
File File = new file (filename);
try {
if (!file.exists ())
File.createnewfile ();
Bufferedoutputstream OS = new Bufferedoutputstream (new FileOutputStream (file));
Os.write (filecontent);
catch (FileNotFoundException e) {
TODO auto-generated Catch block
E.printstacktrace ();
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
; }
}
Fileserver
Copy Code code as follows:
Package rmiupload;
Import java.net.MalformedURLException;
Import java.rmi.Naming;
Import java.rmi.RemoteException;
Import Java.rmi.registry.LocateRegistry;
public class Fileserver {
Filedataservice Filedataservice;
Public Fileserver () {
try {
Filedataservice = new Filedataservice_imp ();
Locateregistry.createregistry (9001);
Naming.rebind ("Rmi://localhost:9001/filedataservice", Filedataservice);
catch (RemoteException e) {
TODO auto-generated Catch block
E.printstacktrace ();
catch (Malformedurlexception e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}
/**
* @param args
*/
public static void Main (string[] args) {
New Fileserver ();
}
}
