java - 如何从服务器向列表中的多个客户端发送消息

Question

我尝试使用以下代码作为服务器向 IP 在列表 mSession 中的客户端发送消息

for (MSession mSession : mSessions)
{
   System.out.println("Inside for each");
   System.out.println("IP TEST : " + mSession.getRemote_Addr());
   ServerSocket srvr = new ServerSocket(1324, 5, InetAddress.getByName(mSession.getRemote_Addr()));
   Socket skt = srvr.accept();
   System.out.println("IP1:" + InetAddress.getByName(mSession.getRemote_Host()));
   System.out.println("IP2:" + skt.getInetAddress().getHostAddress());           
   System.out.print("Server has connected!\n");
   PrintWriter out = new PrintWriter(skt.getOutputStream(), true);
   System.out.print("Sending string: '" + data + "'\n");
   out.print(data);
   out.close();
   skt.close();
   srvr.close();                                         
}

客户端代码:

InetAddress ip = InetAddress.getByName(host[0]);
System.out.println("IP SERVER : " + ip);
Socket skt = new Socket(ip, 1324);// Ip address of server
in = new BufferedReader(new InputStreamReader(skt.getInputStream()));
System.out.print("Received string: ");

while (!in.ready()) {}
data = in.readLine();
System.out.println(in.readLine());

System.out.print("'\n");
Popupapp app = new Popupapp();
app.fdis(data);
in.close();
skt.close();

我收到 bindexception 无法分配请求的地址:JVM_Bind我尝试过其他端口，但异常仍然相同我尝试过端口 8080、8089、8086、8009、1234、8242、8006

请帮我解决这个问题。

我尝试过这个简单的程序，它显示了相同的异常

public class ServerSide extends Thread{

public void run()
{
    while(true)
    {
        String data = "Recieved new notification";
        try {

             ServerSocket srvr = new ServerSocket(1234, 5, InetAddress.getByName("192.168.168.40"));
             Socket skt = srvr.accept();

             skt.getInputStream();

             System.out.print("Server has connected!\n");
             PrintWriter out = new PrintWriter(skt.getOutputStream(), true);
             System.out.print("Sending string: '" + data + "'\n");
             out.print(data);
             out.close();
             skt.close();
             srvr.close();
             Thread.sleep(500);



      }

   catch(Exception e) {
      System.out.print("Whoops! It didn't work!\n" + e);
      try {
        Thread.sleep(1000);
    } catch (InterruptedException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
   }

}
}

Answer 1

原因是您在 foreach 循环内创建服务器套接字。因此，在第一次之后，当第一个客户端被处理并且第一次创建serversocket时，此代码在下一次客户端处理中再次尝试在同一端口上创建另一个serversocket，从而导致绑定(bind)异常。

解决方案是在循环之前创建一个单独的服务器套接字，它将继续在 foreach 循环内接受客户端。如下图所示:

ServerSocket srvr = new ServerSocket(1324, 5, InetAddress.getByName(mSession.getRemote_Addr()));
for (MSession mSession : mSessions)
              {
                  System.out.println("Inside for each");
                  System.out.println("IP TEST : " + mSession.getRemote_Addr());
                  // start accepting client-requests                     
                  Socket skt = srvr.accept();
                  System.out.println("IP1:" + InetAddress.getByName(mSession.getRemote_Host()));
                  System.out.println("IP2:" + skt.getInetAddress().getHostAddress());            
                  System.out.print("Server has connected!\n");
                  PrintWriter out = new PrintWriter(skt.getOutputStream(), true);
                  System.out.print("Sending string: '" + data + "'\n");
                  out.print(data);
                  out.close();
                  skt.close();                                     
              }
                // finally close the server-socket!                
                  srvr.close(); 

<小时/>

根据您的编辑:

您再次在循环内创建 ServerSocket! 不要!!!* 在构造函数(或其他方法)中执行此操作。

public class ServerSide extends Thread{

public ServerSide(){
ServerSocket srvr = new ServerSocket(1234, 5, InetAddress.getByName("192.168.168.40"));
}
public void run()
{
while(true)
{
    String data = "Recieved new notification";
    try {             
         Socket skt = srvr.accept();
         skt.getInputStream();
         System.out.print("Server has connected!\n");
         PrintWriter out = new PrintWriter(skt.getOutputStream(), true);
         System.out.print("Sending string: '" + data + "'\n");
         out.print(data);
         out.close();
         skt.close();
         srvr.close();
         Thread.sleep(500);
  }
catch(Exception e) {
  System.out.print("Whoops! It didn't work!\n" + e);
  try {
    Thread.sleep(1000);
} catch (InterruptedException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}
}

现在，从服务器端的主方法调用它，如下所示:

new ServerSide().start();