java rmi : access control exception, 访问被拒绝

Question

我正在浏览sun网站上的教程，尝试使用RMI。

但是当我尝试启动服务器时出现此错误:

ComputeEngine exception:
java.security.AccessControlException: access denied ("java.net.SocketPermission" "127.0.0.1:1099" "connect,resolve")
    at java.security.AccessControlContext.checkPermission(AccessControlContext.java:372)
    at java.security.AccessController.checkPermission(AccessController.java:559)
    at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
    at java.lang.SecurityManager.checkConnect(SecurityManager.java:1051)
    at java.net.Socket.connect(Socket.java:574)
    at java.net.Socket.connect(Socket.java:528)
    at java.net.Socket.<init>(Socket.java:425)
    at java.net.Socket.<init>(Socket.java:208)
    at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirectSocketFactory.java:40)
    at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMasterSocketFactory.java:146)
    at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:613)
    at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:216)
    at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:202)
    at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:340)
    at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
    at engine.ComputeEngine.main(ComputeEngine.java:31)

有人可以建议如何解决这个问题吗？我如何摆脱这个异常，如何修复它？

这是我遇到异常的地方(我在线右侧画了箭头):

package engine;

import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;
import compute.Compute;
import compute.Task;

public class ComputeEngine implements Compute {

    public ComputeEngine() {
        super();
    }

    public <T> T executeTask(Task<T> t) {
        return t.execute();
    }

    public static void main(String[] args) {
        if (System.getSecurityManager() == null) {
            System.setSecurityManager(new SecurityManager());
        }
        try {
            String name = "Compute";
            Compute engine = new ComputeEngine();
            Compute stub =
                (Compute) UnicastRemoteObject.exportObject(engine, 0);
            Registry registry = LocateRegistry.getRegistry();
            registry.rebind(name, stub); <<<<<------
            System.out.println("ComputeEngine bound");
        } catch (Exception e) {
            System.err.println("ComputeEngine exception:");
            e.printStackTrace();
        }
    }
}

最后，这就是我开始我的程序的方式:

我将在下面留下可能有用的更多相关信息:

这是文件 ~/.server_policy:

grant codeBase "file:/home/jenia/Documents/eclipse/workspace/asti01/bin" {
    permission java.security.AllPermission;
};

这是项目目录树:

/home/jenia/Documents/eclipse/workspace/asti01$ tree
.
├── bin
│   ├── client
│   │   ├── ComputePi.class
│   │   └── Pi.class
│   ├── compute
│   │   ├── Compute.class
│   │   └── Task.class
│   └── engine
│       └── ComputeEngine.class
└── src
    ├── client
    │   ├── ComputePi.java
    │   └── Pi.java
    ├── compute
    │   ├── Compute.java
    │   └── Task.java
    ├── compute.jar
    └── engine
        └── ComputeEngine.java

这是文件夹 ~/public_html 的树

/home/jenia/public_html/
└── classes
    ├── client
    │   └── Pi.class
    └── compute.jar

Answer 1

重申@EJP 的原始评论:

忽略教程中与配置/使用 SecurityManager 相关的所有内容。不要尝试使用远程代码加载。这些“功能”极大地增加了使用 rmi 的复杂性，并且 99% 的用户实际上并不需要它们。