Question

在某些java代码中获取这些错误

http://tutorials.jenkov.com/java-multithreaded-servers/multithreaded-server.html

Exception in thread "Thread-0" java.lang.RuntimeException: Cannot open port 8080
at servers.MultiThreadedServer.openServerSocket(MultiThreadedServer.java:61)
at servers.MultiThreadedServer.run(MultiThreadedServer.java:22)
at java.lang.Thread.run(Thread.java:679)
Caused by: java.net.BindException: Address already in use
at java.net.PlainSocketImpl.socketBind(Native Method)
at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:353)
at java.net.ServerSocket.bind(ServerSocket.java:336)
at java.net.ServerSocket.<init>(ServerSocket.java:202)
at java.net.ServerSocket.<init>(ServerSocket.java:114)
at servers.MultiThreadedServer.openServerSocket(MultiThreadedServer.java:59)
... 2 more
     Exception in thread "main" Stopping Server
  java.lang.NullPointerException
at servers.MultiThreadedServer.stop(MultiThreadedServer.java:51)
at servers.Dispatch.main(Dispatch.java:18)

我制作了这些文件

WorkerRunnable.java

package servers;

import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.net.Socket;

/**

*/
public class WorkerRunnable implements Runnable{

protected Socket clientSocket = null;
protected String serverText   = null;

public WorkerRunnable(Socket clientSocket, String serverText) {
    this.clientSocket = clientSocket;
    this.serverText   = serverText;
}

public void run() {
    try {
        InputStream input  = clientSocket.getInputStream();
        OutputStream output = clientSocket.getOutputStream();
        long time = System.currentTimeMillis();
        output.write(("HTTP/1.1 200 OK\n\nWorkerRunnable: " +
                this.serverText + " - " +
                time +
                "").getBytes());
        output.close();
        input.close();
        System.out.println("Request processed: " + time);
    } catch (IOException e) {
        //report exception somewhere.
        e.printStackTrace();
    }
  }
 }

MultiThreadedServer.java

package servers;

import java.net.ServerSocket;
import java.net.Socket;
import java.io.IOException;

public class MultiThreadedServer implements Runnable{

protected int          serverPort   = 8080;
protected ServerSocket serverSocket = null;
protected boolean      isStopped    = false;
protected Thread       runningThread= null;

public MultiThreadedServer(int port){
    this.serverPort = port;
}

public void run(){
    synchronized(this){
        this.runningThread = Thread.currentThread();
    }
    openServerSocket();
    while(! isStopped()){
        Socket clientSocket = null;
        try {
            clientSocket = this.serverSocket.accept();
        } catch (IOException e) {
            if(isStopped()) {
                System.out.println("Server Stopped.") ;
                return;
            }
            throw new RuntimeException(
                "Error accepting client connection", e);
        }
        new Thread(
            new WorkerRunnable(
                clientSocket, "Multithreaded Server")
        ).start();
    }
    System.out.println("Server Stopped.") ;
}


private synchronized boolean isStopped() {
    return this.isStopped;
}

public synchronized void stop(){
    this.isStopped = true;
    try {
        this.serverSocket.close();
    } catch (IOException e) {
        throw new RuntimeException("Error closing server", e);
    }
}

private void openServerSocket() {
    try {
        this.serverSocket = new ServerSocket(this.serverPort);
    } catch (IOException e) {
        throw new RuntimeException("Cannot open port 8080", e);
    }
}

}

Dispatch.java

 package servers;

 public class Dispatch {

/**
 * @param args
 */
public static void main(String[] args) {
    MultiThreadedServer server = new MultiThreadedServer(9000);
    new Thread(server).start();

    try {
        Thread.sleep(20 * 1000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    System.out.println("Stopping Server");
    server.stop();

}

}

Answer 1

端口8080可能已被您计算机中的其他服务使用（它通常由Web服务器使用，如Tomcat）。尝试在另一个端口号中启动服务器。

Answer 2

其他程序正在使用您的计算机的端口8080

终止使用端口8080的程序

您可以通过以下命令（Windows）找到该程序：

netstat -o -n -a | findstr 0.0:8080

示例输出：

TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING 8704

然后，您可以使用任务管理器使用PID 8704找到该程序并终止它。

详情请参阅here。

使用其他端口

您可以更改

protected int serverPort   = 8080;

到

protected int serverPort   = 8888;

或者

MultiThreadedServer server = new MultiThreadedServer(8888);

因此使用端口8888代替8080。

Answer 3

您的代码容易出错且误导。您将服务器端口指定为9000，并在异常块中将其打印为8080，并在类声明中初始化它为8080。正在使用的实际端口是端口9000，而不是8080。尝试另一个端口 - 请尝试8080。

Java Server示例错误

3 个答案: