尝试连接到RMI注册表但获取java时出现异常。网连接异常：连接被拒绝：连接

Question

我有两台电脑。在其中一个服务器上，正在运行RMI注册表，该注册表仅由以下代码创建：

package main;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.util.Scanner;

public class TheRegistry{

    public static void main(String[] args) {
        try {
            Registry reg = LocateRegistry.createRegistry(2020);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally{
            System.out.println("Registry Created");
            Scanner input = new Scanner(System.in);
            input.nextInt();
            System.exit(0);
        }
    }
}

另一台计算机的服务器正试图在该注册表上注册一个对象，但是，它遇到了一个异常。以下是服务器的代码：

import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;
import java.rmi.*;

public class TextScramblerServer implements TextScramblerInterface 
{
    private static Remote obj; 
    // main method to export
    @Override //Return input text as-is.
    public String testInputText(String inputText) {

        return "Your input text is: " + inputText;
    }

    @Override //Return the string reversed.
    public String reverse(String inputText) {
        String reversedInput = "";
        for(int i=0; i<inputText.length();i++)
        {
            reversedInput=reversedInput+inputText.charAt((inputText.length()-1)-i);
        }
        return "Result: "+reversedInput;
    }

    @Override //Return the string scrambled.
    public String scramble(String inputText) {
        String scrambledInput="";

        for(int i=0; i<inputText.length();i++)
        {
            if(i%2==0)
            {
                scrambledInput=scrambledInput+inputText.charAt(i);
            }
            else
            {
                scrambledInput=inputText.charAt(i)+scrambledInput;
            }
        }
        return "Result: "+scrambledInput;
    }

    public void exportServer() throws Exception {
        System.setSecurityManager(new RMISecurityManager());
        obj = UnicastRemoteObject.exportObject(this, 2022);
        Registry registry = LocateRegistry.getRegistry("132.205.94.50", 2020);
        registry.bind("test", obj);
    }

    public static void main(String[] args) {
        try {
            (new TextScramblerServer()).exportServer();
            System.out.println("Server is up and running");
        }
        catch(Exception e){
            e.printStackTrace();
            try {
                UnicastRemoteObject.unexportObject(obj, true); //close port
            } catch (NoSuchObjectException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        }
    }
}

我不断发现错误：

java.rmi.ConnectException: Connection refused to host: 132.205.94.50; nested exception is: 
    java.net.ConnectException: Connection refused: connect
    at sun.rmi.transport.tcp.TCPEndpoint.newSocket(Unknown Source)
    at sun.rmi.transport.tcp.TCPChannel.createConnection(Unknown Source)
    at sun.rmi.transport.tcp.TCPChannel.newConnection(Unknown Source)
    at sun.rmi.server.UnicastRef.newCall(Unknown Source)
    at sun.rmi.registry.RegistryImpl_Stub.bind(Unknown Source)
    at TextScramblerServer.exportServer(TextScramblerServer.java:57)
    at TextScramblerServer.main(TextScramblerServer.java:62)
Caused by: java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(Unknown Source)
    at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(Unknown Source)
    ... 7 more
java.rmi.NoSuchObjectException: object not exported
    at sun.rmi.transport.ObjectTable.unexportObject(Unknown Source)
    at java.rmi.server.UnicastRemoteObject.unexportObject(Unknown Source)
    at TextScramblerServer.main(TextScramblerServer.java:68)

我不明白为什么会这样。我想我什么都试过了

Answer 1

您的注册表已被垃圾收集，您的IP地址错误，或者它是公共IP地址，您尚未配置端口转发

您需要将注册表引用存储在一个静态对象中，以克服垃圾收集，尽管当rmiregistry.exe已经存在时，该程序的意义让我完全无法理解

反正你找错人了。只能绑定到本地主机上运行的RMI注册表。因此，在绑定或解除绑定时，永远不需要使用除"localhost"之外的注册表主机名

得到NoSuchObjectException的原因是您试图取消导出存根，它由obj引用，这是返回存根的UnicastRemoteObject.exportObject()的结果。参见Javadoc。您需要保存new TextScramblerServer()的结果并取消报告