使用套接字和 AsyncTask 强制关闭

Question

大家好……

请在下面查看我的课程代码和我的 LogCat...

我在尝试连接时强制关闭。如果有人可以帮助我弄清楚为什么会非常感激。

基本上代码在做什么：

1. 从意图中获取 IP 地址。
2. 使用 32 端口连接到 IP
3. 然后发送一个命令，等待响应再发送另一个命令。
4. 在我们发送 2 个命令后，我应该得到“SNX_COM>”的响应
5. 一旦建立连接，我希望连接保持打开状态，以便在单击按钮时发送特定命令。

请帮忙:)

package com.smarte.smartipcontrol;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;

public class IPControl extends Activity {

private Socket socket;
private String serverIpAddress = "com.smarte.smartipcontrol.ACTU_IP";
private static final int REDIRECTED_SERVERPORT = 32;
public PrintWriter out;
public BufferedReader in;
public String data;
public Object pd;


public void getModel(View view) {
    try {
        out.println("[m\r\n");
        //System.out.print("root\r\n");
        while(!in.ready());
        String textStatus = readBuffer();

    } catch(IOException e) {}
}


@Override
public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);

   setContentView(R.layout.act_ipcontrol);


   try{   

   this.pd = ProgressDialog.show(this, "Loading..", "Please Wait...", true, false);
    new AsyncAction().execute();

   }catch (Exception e) {
       e.printStackTrace();
   }

   }



private class AsyncAction extends AsyncTask<String, Void, String> {
   protected String doInBackground(String... args) { 
   try {
 InetAddress serverAddr = InetAddress.getByName(serverIpAddress);
 socket = new Socket(serverAddr, REDIRECTED_SERVERPORT);
} catch (UnknownHostException e1) {
 e1.printStackTrace();
} catch (IOException e1) {
 e1.printStackTrace();
}
try {
 out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true); in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
 while (! in .ready());
 readBuffer();
 out.println("root\r\n");
 //System.out.print("root\r\n");
 while (! in .ready());
 readBuffer();
 out.println("root\r\n");
 //System.out.print("root\r\n");
 while (! in .ready());
 String msg = "";

while ( in .ready()) {
 msg = msg + (char) in .read();
}
} catch (IOException e) {}

       return null;//returns what you want to pass to the onPostExecute()
   }

   protected void onPostExecute(String result) {

   //resultis the data returned from doInbackground

       IPControl.this.data = result;




       if (IPControl.this.pd != null) {
           ((Dialog) IPControl.this.pd).dismiss();
       }
    }


}

private String readBuffer() throws IOException {
    String msg = "";

    while(in.ready()) {
        msg = msg + (char)in.read();
    }
    //System.out.print(msg);
    if(msg.indexOf("SNX_COM> ") != -1) return msg.substring(0, msg.indexOf("SNX_COM> "));
    else return msg;
}

}

Logcat.......

12-03 15:39:56.346: E/AndroidRuntime(2697): FATAL EXCEPTION: AsyncTask #5
12-03 15:39:56.346: E/AndroidRuntime(2697): java.lang.RuntimeException: An error occured while executing doInBackground()
12-03 15:39:56.346: E/AndroidRuntime(2697):     at android.os.AsyncTask$3.done(AsyncTask.java:299)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at java.util.concurrent.FutureTask.run(FutureTask.java:239)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at java.lang.Thread.run(Thread.java:856)
12-03 15:39:56.346: E/AndroidRuntime(2697): Caused by: java.lang.NullPointerException
12-03 15:39:56.346: E/AndroidRuntime(2697):     at com.smarte.smartipcontrol.IPControl$AsyncAction.doInBackground(IPControl.java:71)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at com.smarte.smartipcontrol.IPControl$AsyncAction.doInBackground(IPControl.java:1)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
12-03 15:39:56.346: E/AndroidRuntime(2697):     at java.util.concurrent.FutureTask.run(FutureTask.java:234)
12-03 15:39:56.346: E/AndroidRuntime(2697):     ... 4 more

Answer 1

我认为你的问题在这里：

 InetAddress serverAddr = InetAddress.getByName(serverIpAddress);
 socket = new Socket(serverAddr, REDIRECTED_SERVERPORT);

我找不到您的 serverIpAddress 分配位置，因此您得到 NullPointerException。