Java RMI : ConnectException: Connection timed out: connect

Question

我意识到这个问题已经被问了很多次，也被回答了很多次(通常来自 EJP，他显然知道他的东西!)，但我仍然在挣扎。

我“偷了”一个简单的 RMI 添加服务器和客户端。(谢谢你， http://www.scs.ryerson.ca/mes/courses/cps530/programs/rmi/Schildt/addTwoNumbers.html然后，他引用了 P.Naughton 和 H.Schildt 所著的《Java 2:完整引用》第 24 章。)

无论我尝试什么，我仍然会遇到“连接超时”异常。谁能看到我做错了什么吗？

我怀疑防火墙出了问题，但如果是这样，我不知道该告诉我的 IT 人员修复和更改什么。

提前致谢!

界面:

public interface AddServerIntf extends Remote {
    double add(double d1, double d2) throws RemoteException;
}

服务器:

public class SimpleRMIExServer {
    public static void main(String[] args) throws Exception {    
        System.out.println("Class name " + SimpleRMIExServer.class.getSimpleName());
        System.out.println("Path " + System.getProperty("user.dir"));
        System.setProperty("java.rmi.server.codebase",
                "file:///D:\\SimpleRMIExample\\lib\\SimpleRMIExample.jar");
        Registry registry;
        try {
            registry = LocateRegistry.createRegistry(1099);
        } catch (RemoteException remoteException) {
            registry = LocateRegistry.getRegistry(1099);
        }
        AddServerImpl addServerImpl = new AddServerImpl();
        registry.bind("AddServer", addServerImpl);
        System.out.println("Located Registry " + registry.toString());
        for (String boundName : registry.list()) {
            System.out.println("Name bound: " + boundName);
        }
        Naming.rebind("SERVERNAME", addServerImpl);
        System.out.println("Registry: " + registry);
        System.out.println("");
        System.out.println("Remote: " + addServerImpl);
    }    
}
public class AddServerImpl extends UnicastRemoteObject implements AddServerIntf {
    public AddServerImpl() throws RemoteException {
    }

    @Override
    public double add(double d1, double d2) throws RemoteException {
        return d1 + d2;
    }
}

客户:

public class SimpleRMIExClient {
   public static void main(String[] args) throws Exception {
     final Registry registry = LocateRegistry.getRegistry("SERVERNAME", 1099);
     AddServerIntf addServerIntf = (AddServerIntf) registry.lookup("AddServer");
     System.out.println("The first number is: " + 10);
     double d1 = Double.valueOf(10).doubleValue();
     System.out.println("The second number is: " + 15);
     double d2 = Double.valueOf(15).doubleValue();
     System.out.println("The sum is: " + addServerIntf.add(d1, d2)); //Exception occurs here.
   }
}

服务器输出:

D:\>java -jar SimpleRMIExServer.jar
Class name SimpleRMIExServer
Path D:\
Located Registry RegistryImpl[UnicastServerRef [liveRef: [endpoint:[XX.XX.XX.XX:
1099](local),objID:[0:0:0, 0]]]]
Name bound: AddServer
Registry: RegistryImpl[UnicastServerRef [liveRef: [endpoint:[XX.XX.XX.XX:1099](l
ocal),objID:[0:0:0, 0]]]]

Remote: AddServerImpl[UnicastServerRef [liveRef: [endpoint:[XX.XX.XX.XX:54119](l
ocal),objID:[2a7202aa:14492e5ea89:-7fff, -5034491972061237368]]]]

客户端的输出:

debug:
The first number is: 10
The second number is: 15
Exception in thread "main" java.rmi.ConnectException: Connection refused to host: XX.XX.XX.XX; nested exception is: 
    java.net.ConnectException: Connection timed out: connect
    at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619)
    at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619)
    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.invoke(UnicastRef.java:129)
    at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:194)
    at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:148)
    at com.sun.proxy.$Proxy0.add(Unknown Source)
    at com.sun.proxy.$Proxy0.add(Unknown Source)
    at simplermiexclient.SimpleRMIExClient.main(SimpleRMIExClient.java:35)
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:579)
    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:147)
    at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:613)
    ... 7 more
Java Result: 1
BUILD SUCCESSFUL (total time: 1 minute 33 seconds)

此外，我使用了命令 netstat -a 它显示:

LocalAddress       ForeignAddress    State
0.0.0.0:1099       SERVERNAME:0      LISTENING
[::]:1099          SERVERNAME:0      LISTENING
XX.XX.XX.XX:53373  SERVERNAME:1099   ESTABLISHED

(还有许多其他行)我还看到过:

LocalAddress       ForeignAddress    State
XX.XX.XX.XX:54138   SERVERNAME:1099  TIME_WAIT

编辑:我尝试添加:

System.setProperty("java.rmi.server.hostname", "SERVERNAME");

根据 EJP 对许多其他人的建议，在设置代码库系统属性后立即连接到服务器，以阅读 Java RMI FAQ A.1。

当我这样做时，这是堆栈跟踪:

debug:
The first number is: 10
The second number is: 15
Exception in thread "main" java.rmi.ConnectException: Connection refused to host: SERVERNAME; nested exception is: 
    java.net.ConnectException: Connection timed out: connect
    at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619)
    at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619)
    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.invoke(UnicastRef.java:129)
    at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:194)
    at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:148)
    at com.sun.proxy.$Proxy0.add(Unknown Source)
    at com.sun.proxy.$Proxy0.add(Unknown Source)
    at simplermiexclient.SimpleRMIExClient.main(SimpleRMIExClient.java:35)
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:579)
    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:147)
    at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:613)
    ... 7 more
Java Result: 1
BUILD SUCCESSFUL (total time: 1 minute 15 seconds)

回答我自己的问题:我已经找到了我的问题的答案。我喜欢看到其他人这样做，能够自己说出来真是太好了。

我的最终解决方案是防火墙问题，但我想向任何人提供如何解决我的问题的建议。

1. 将其分解。将上面的代码(实际上不是我的代码)制作一个更简单的 RMI 服务器版本并进行测试。

2. 从小事做起，逐步提高。从本地主机开始，确保其工作正常，然后在单独的 PC 上进行测试(我有一台虚拟 PC)，然后在您的服务器上进行测试。

3. 寻求帮助!我在互联网上搜索了很多。谢谢你，EJP!另外，一旦我最终让它在虚拟 PC 上运行，但不能在服务器上运行，然后我让 IT 人员参与其中，他们发现了两者之间的差异。 “PC 上有一个与 Java 相关的防火墙设置，但服务器上没有设置。” - IT 专家(参见:http://windows.microsoft.com/en-us/windows/communicate-through-windows-firewall#1TC=windows-7)

我意识到我在这里所说的并不是什么新鲜事，我知道我已经听过很多次了，但有时需要听一千遍才能最终接受。虽然它还没有对我的 child 起作用。 ;-)

祝你好运。

Answer 1

(通过问题编辑回答。转换为社区 wiki 答案。请参阅 Question with no answers, but issue solved in the comments (or extended in chat) )

OP 写道:

Answering my own question: I have figured out the answer to my problem. I love to see others do that, it's good to be able to say it myself.

My final solution was a firewall problem, but I'd like to provide suggestions to anyone out there for HOW I solved my problem.

1. Break it down. Take my code above that really isn't my code and make a much simpler version of the RMI server and test it.

2. Start small and work your way up. Start with localhost make sure that works, then test on a separate PC (I had a virtual PC), then test on your server.

3. GET HELP! I searched the Internet A LOT. Thank you, EJP! Also, once I finally got it working on the Virtual PC, but not on the server, then I go my IT guys involved and they found a difference between the two. "There was a firewall setting on the PC that was related to Java that was not set on the server." - IT Guy (See: http://windows.microsoft.com/en-us/windows/communicate-through-windows-firewall#1TC=windows-7 )

I realize what I've said here is nothing new and I know I've heard it many times, but sometimes it takes hearing it a thousand times to finally accept. Although it hasn't worked with my kids yet. ;-)

Good Luck.