菜鸟提问,java在命令行里面执行的问题

Question

我写了个java程序,在eclipse里面点运行的时候就没有问题,一切正常,数据也正常.
但是我在命令行里面用javac执行正常,然后java执行的时候就出错了.
Exception in thread "main" java.lang.NoClassDefFoundError: d:\java\Server4
Caused by: java.lang.ClassNotFoundException: d:\java\Server4
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClassInternal(Unknown Source)这是为啥哪?
我在linux下运行也是这样的错误.

Answer 1

类没找到，贴一下你的程序和执行的java命令

Answer 2

import java.net.*;
//import java.io.*;
import java.util.*;
import java.io.PrintWriter;
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class Server4 {
        private ServerSocket server;
        private BManager bMan=new BManager();
        
        public Server4(){}
        void startServer()
        {
         String xml = "<cross-domain-policy>";
            xml = xml + "<allow-access-from domain=\"*\" to-ports=\"*\" />";
            xml = xml + "</cross-domain-policy>";
                try{
                
                        server=new ServerSocket(8888);
                        //protocol.sendStringToSingleClient(protocol.getUser(), "<?xml version=\"1.0\"?><cross-domain-policy><site-control permitted-cross-domain-policies=\"all\"/><allow-access-from domain=\"*\" to-ports=\"*\"/></cross-domain-policy>\0");
                        //System.out.println("服务器套接字建立完毕");
                        
                        while(true)
                        {
                                Socket socket=server.accept();
                                BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                                PrintWriter pw = new PrintWriter(socket.getOutputStream());
                                char[] by = new char[22];
                                br.read(by,0,22);
                                String head = new String(by);
                                if(head.equals("<policy-file-request/>"))
                                {
                                        pw.print(xml + "\0");
                                        pw.flush();
                                }
                                new Chat_Thread(socket).start();
                                bMan.add(socket);
                                bMan.sendClientInfo();
                        }
                }catch(Exception e){
                        //System.out.println(e);
                }
        }
        public static void main(String[] args) {
                Server4 server=new Server4();
                server.startServer();
        }
        class Chat_Thread extends Thread 
        {
                Socket socket; 
                private BufferedReader reader;
                private PrintWriter writer;
                Chat_Thread(Socket socket)
                {
                        this.socket=socket;
                }
                public void run()
                {
                        
                        try
                        {
                                reader=new BufferedReader(new InputStreamReader(socket.getInputStream(),"utf8"));
                                writer=new PrintWriter(socket.getOutputStream(),true);
                                String msg;
                                while((msg=reader.readLine())!=null)
                                {
                                        bMan.sendToAll(msg);
                                }
                        }catch(Exception e)
                        {
                                
                        }finally
                        {
                                try {
                                        bMan.remove(socket);
                                        if(reader !=null) reader.close();
                                        if(writer !=null) writer.close();
                                        if(socket !=null) socket.close();
                                        reader=null;
                                        writer=null;
                                        socket=null;
                                        bMan.sendClientInfo();
                                } catch (Exception e) {}
                        }
                        
                }
        }
}class BManager extends Vector
{
        BManager (){}
        void add(Socket sock)
        {
                super.add(sock);
        }
        void remove(Socket sock)
        {
                super.remove(sock);
        }
        synchronized void sendToAll(String msg)
        {
                PrintWriter writer=null;
                Socket sock;
                for(int i=0;i<size();i++)
                {
                        sock=(Socket)elementAt(i);
                        try
                        {
                                writer=new PrintWriter(sock.getOutputStream(),true);
                        }catch(Exception ie){}
                        if(writer!=null) writer.println(msg);
                }
        }        synchronized void sendClientInfo()
        {
        }
}

Answer 3

这是我在linux下执行的报错
[root@localhost ~]# java /root/Server4
Exception in thread "main" java.lang.NoClassDefFoundError: .root.Server4
   at gnu.java.lang.MainThread.run(libgcj.so.7rh)
Caused by: java.lang.ClassNotFoundException: .root.Server4 not found in gnu.gcj.runtime.SystemClassLoader{urls=[file:./,file:/usr/java/jdk1.6.0_07/lib/dt.jar,file:/usr/java/jdk1.6.0_07/lib/tools.jar], parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}
   at java.net.URLClassLoader.findClass(libgcj.so.7rh)
   at gnu.gcj.runtime.SystemClassLoader.findClass(libgcj.so.7rh)
   at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
   at java.lang.ClassLoader.loadClass(libgcj.so.7rh)

Answer 4

问题是file:/usr/java/jdk1.6.0_07/lib/dt.jar,file:/usr/java/jdk1.6.0_07/lib/tools.jar 这两个的路径是没有错的啊

Answer 5

找到你的class文件，在该目录下用javac

Answer 6

我将你的程序编译运行没有问题
C:\>javac Server4.java
注意：Server4.java 使用了未经检查或不安全的操作。
注意：要了解详细信息，请使用 -Xlint:unchecked 重新编译。C:\>java Server4
server.startServer() runing为了能看出执行结果，我修改了一下main方法．
 public static void main(String[] args) { 
                Server4 server=new Server4(); 
                System.out.println("server.startServer() runing");
                server.startServer(); 
        } 
需要配jdk地址，在环境变量Path中加入C:\Program Files\Java\jdk1.6.0_10\bin;
或者C:\Program Files\Java\jdk1.5.0\bin
我用了两个版本的 jdk都可以执行．
我这里没有linux环境，无法在linux环境测试。
根据上面的原因，我怀疑是你linux环境jdk环境配置的问题。