刚刚有一个关于我遇到的奇怪运行时错误的问题。我正在使用一个 JSON 服务器，该服务器在外部源提示时使用 JSON 对象进行响应。然而，就目前而言，我只是试图在发送 JSON 对象之前启动并运行它。我的代码在没有指定任何类路径的情况下进行编译，但是在运行时，它会抛出NoClassDefFoundError如下所示：
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/lang/exception/NestableRuntimeException
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at ExampleServer.sendData(ExampleServer.java:76)
at ExampleServer.runServer(ExampleServer.java:30)
at ExampleServer.main(ExampleServer.java:15)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang.exception.NestableRuntimeException
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
... 15 more
我的代码如下：
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.lang.*;
import net.sf.json.*;
public class ExampleServer{
private DataOutputStream output;
private DataInputStream input;
private ServerSocket server;
private Socket connection;
public static void main(String[] args){
new ExampleServer().runServer();
}
public void ExampleServer(){
System.out.println("Server object created");
}
public void runServer(){
try{
server = new ServerSocket(12345,100);
while(true){
try{
waitForConnection();
getStreams();
processConnection();
sendData("Text");
} catch(Exception e){
System.out.println("Server Terminated Exception.");
} finally {
closeConnection();
}
}
} catch(Exception e){
e.printStackTrace();
}
}
private void waitForConnection(){
try{
System.out.println("Waiting for connection.");
connection = server.accept();
System.out.println("Connection received from " + connection.getInetAddress().getHostName());
} catch (IOException e){
System.out.println(e);
}
}
private void getStreams() throws IOException{
output = new DataOutputStream(connection.getOutputStream());
input = new DataInputStream(connection.getInputStream());
System.out.println("Got streams");
}
private void processConnection() throws IOException{
sendData("This is a test message");
}
private void closeConnection(){
try{
if(output != null && connection != null){
sendData("SEVER>>> TERMINATE");
output.close();
connection.close();
}
} catch (IOException e){
e.printStackTrace();
}
}
private void sendData(String message){
try{
JSONObject g = new JSONObject();
g.put("message", message);
System.out.println(g.toString());
} catch (Exception e){
System.out.println("Error writing object");
}
}
}
并且 JSON 文件夹与 位于同一目录中ExampleServer.java，JSON 类net/sf/json位于我的导入中指定的位置。为什么它直到运行时才起作用？由于某种原因，我的类路径不正确吗？包含必要的类路径的适当语法是什么？
提前致谢