JavaRMI添加示例

Question

我正在实现一个简单的JavaRMI应用程序。它的主要目标是加2个整数。代码源如下：客户端和服务器端的AdditionInterfaceimport java。rmi.*；公共接口添加接口扩展远程{public int add（int a，int b）抛出RemoteException；}

附加JAVA

 import java.rmi.*;
 import java.rmi.server.*;

 public class Addition extends UnicastRemoteObject
 implements AdditionInterface {

 public Addition () throws RemoteException { }

 public int add(int a, int b) throws RemoteException {
 int result=a+b;
 return result;
 }
 }

附加服务器

import java.rmi.*;
 import java.rmi.server.*;

 public class AdditionServer {
 public static void main (String[] argv) {
 try {
 System.setSecurityManager(new SecurityManager());

 Addition Hello = new Addition();
 Naming.rebind("rmi://localhost/ABC", Hello);

 System.out.println("Addition Server is ready.");
 }catch (Exception e) {
 System.out.println("Addition Server failed: " + e);
 }
 }
}

添加客户端

import java.rmi.*;

 public class AdditionClient {
 public static void main (String[] args) {
 AdditionInterface hello;
 try {
 System.setSecurityManager(new SecurityManager());
 hello = (AdditionInterface)Naming.lookup("rmi://localhost/ABC");
 int result=hello.add(9,10);
 System.out.println("Result is :"+result);

 }catch (Exception e) {
 System.out.println("HelloClient exception: " + e);
 }
 }
 }

客户端和服务器端的安全策略

    grant {
        permission java.security.AllPermission;

  };

然而，我得到了HelloClient例外：java。安全AccessControlException:拒绝访问（“java.net.SocketPermission”“127.0.0.1:1099”“连接，解决”）错误




Answer 1

您必须首先启动RMI注册表。试着打电话

java.rmi.registry.LocateRegistry.createRegistry(1099);

在尝试（重新）绑定远程对象之前。我不确定，但如果注册表已经启动，此调用可能会失败。第二个问题可能是SecurityManager应用的策略没有连接/解析localhost的权限。尝试ro注释掉System.setSecurityManager（new SecurityManager（））；以开始。默认的java策略文件只有一个SocketPersion被授予：

permission java.net.SocketPermission "localhost:0", "listen";