Question

我创建了一个包含服务和活动的Android测试程序。在活动中我开始粘性服务。服务每10秒发出一次http请求。如果我不退出活动，一切正常。如果我退出，服务有时会工作，然后被系统杀死并重新启动。重启后，有时http请求有效，有时会给出错误消息：

09-28 14:55:18.053 31161-31184/home.xmpp W/System.err: java.net.ConnectException: failed to connect to www.ya.ru/87.250.250.242 (port 80) after 15000ms: isConnected failed: ECONNREFUSED (Connection refused)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at libcore.io.IoBridge.isConnected(IoBridge.java:238)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at libcore.io.IoBridge.connectErrno(IoBridge.java:171)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at libcore.io.IoBridge.connect(IoBridge.java:122)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:456)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at java.net.Socket.connect(Socket.java:882)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at com.android.okhttp.internal.Platform.connectSocket(Platform.java:174)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at com.android.okhttp.Connection.connect(Connection.java:152)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:276)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:211)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:382)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at com.android.okhttp.internal.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:106)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at com.android.okhttp.internal.http.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:217)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at home.xmpp.MyService.sendPostRequest(MyService.java:160)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at home.xmpp.MyService$MyTask.doInBackground(MyService.java:128)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at home.xmpp.MyService$MyTask.doInBackground(MyService.java:109)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at android.os.AsyncTask$2.call(AsyncTask.java:292)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at java.lang.Thread.run(Thread.java:818)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err: Caused by: android.system.ErrnoException: isConnected failed: ECONNREFUSED (Connection refused)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:     at libcore.io.IoBridge.isConnected(IoBridge.java:223)
09-28 14:55:18.053 31161-31184/home.xmpp W/System.err:  ... 21 more

出现此错误后，以下请求也将失败。我尝试在另一个进程中启动服务，尝试在新的IntentService中启动每个http请求，尝试在此错误后重启服务，但没有结果。如果发生错误，则其他后续请求也会出错。只有应用程序重启有帮有谁遇到过这样的问题？如何建立稳定的连接？我读了很多主题，但找不到合适的答案。

MyService.java

package home.xmpp;

import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.ComponentCallbacks2;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Handler;
import android.os.IBinder;
import android.util.Log;

import javax.net.ssl.HttpsURLConnection;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

public class MyService extends Service implements ComponentCallbacks2 {
private Boolean disconnectAppeared = false;
static MyService instance;
private Handler mHandler = new Handler();
MyTask mt;
Boolean mtruned = false;


public static MyService getInstance(){
    return instance;
}

@Override
public IBinder onBind(final Intent intent) {
    //throw new UnsupportedOperationException("Not yet implemented");
    return new LocalBinder<MyService>(this);
}

@Override
public void onCreate() {
    super.onCreate();
    instance = this;
    mHandler.postDelayed(timeUpdaterRunnable, 100);
    Log.e("MyService"," created");
}

@Override
public int onStartCommand(final Intent intent, final int flags,
                          final int startId) {
    return Service.START_STICKY;
}

@Override
public boolean onUnbind(final Intent intent) {
    return super.onUnbind(intent);
}

@Override
public void onDestroy() {
    super.onDestroy();
    Log.e("MyService"," destroyed");
    mHandler.removeCallbacks(timeUpdaterRunnable);
}

public void onTrimMemory(int level) {
    switch (level) {
        case ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL: //Release any memory that your app doesn't need to run.
            //the system will begin killing background processes. !!!
            Log.e("Memory level","4");
            break;
        default:
            break;
    }
}

private Runnable timeUpdaterRunnable = new Runnable() {
    public void run() {
        if (mtruned == false) {
            Log.e("Time", " update");
            mt = new MyTask();
            mt.execute();
            mHandler.postDelayed(this, 10000);
        } else {
            cancelTask();
        }
    }
};

private void cancelTask() {
    if (mt == null) return;
    Log.d("MyService", "cancel result: " + mt.cancel(false));
}


    class MyTask extends AsyncTask<String,Void,String> {
        @Override
        protected void onPreExecute() {
            mtruned = true;
            super.onPreExecute();
        }
        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            Log.e("http","updated");
            mtruned = false;
        }
        @Override
        protected String doInBackground(String... params) {
            String result = "";
            HashMap<String,String> data = new HashMap<>();
            data.put("data", "data");
                result = sendPostRequest("http://www.ya.ru", data);
            return result;
        }
        @Override
        protected void onCancelled() {
            super.onCancelled();
            mtruned = false;
        }
}

public String sendPostRequest(String requestURL,
                              HashMap<String, String> postDataParams) {
    //Creating a URL
    URL url;

    //StringBuilder object to store the message retrieved from the server
    StringBuilder sb = new StringBuilder();
    try {
        //Initializing Url
        url = new URL(requestURL);

        //Creating an httmlurl connection
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        //Configuring connection properties
        conn.setReadTimeout(15000);
        conn.setConnectTimeout(15000);
        conn.setRequestMethod("POST");
        conn.setDoInput(true);
        conn.setDoOutput(true);

        //Creating an output stream
        OutputStream os = conn.getOutputStream();

        //Writing parameters to the request
        //We are using a method getPostDataString which is defined below
        BufferedWriter writer = new BufferedWriter(
                new OutputStreamWriter(os, "UTF-8"));
        writer.write(getPostDataString(postDataParams));

        writer.flush();
        writer.close();
        os.close();
        int responseCode = conn.getResponseCode();

        if (responseCode == HttpsURLConnection.HTTP_OK) {

            BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            sb = new StringBuilder();
            String response;
            //Reading server response
            while ((response = br.readLine()) != null){
                sb.append(response);
            }
        }

    } catch (Exception e) {
        e.printStackTrace();
    }
    return sb.toString();
}

private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
    StringBuilder result = new StringBuilder();
    boolean first = true;
    for (Map.Entry<String, String> entry : params.entrySet()) {
        if (first)
            first = false;
        else
            result.append("&");

        result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
        result.append("=");
        result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
    }

    return result.toString();
}


}

更新05.10.17我仍然没有找到解决方案。我在Android 4.1.2上测试了这个程序。它工作正常。在Android 5.1.1上，它在退出活动后大约3分钟工作，然后我收到连接拒绝错误。当我返回活动时，错误消失。在Android 6.0.1上类似的情况，但是java.net.SocketTimeoutException的错误略有不同：10000ms后无法连接到/94.130.25.242（端口80）。我认为系统会在一段时间后阻止服务中的网络活动，但从不在活动中阻止（？）。

更新05.10.17 我注意到连接不仅在重新启动服务后消失，而且在退出活动后2-3分钟后消失。当我返回活动时，连接将恢复。我制作了一段视频Link 更新06.10.17 一位Android专家告诉我，这个问题只出现在小米手机中。几分钟后，MIUI拒绝网络连接。只有OkHttp有帮助。我会尝试一下，并会在这里提出反馈。

Answer 1

A＆＃34;连接失败：ECONNREFUSED（拒绝连接）＆＃34;很可能意味着没有任何东西正在侦听该端口和该IP地址。可能的解释包括：

服务已崩溃或尚未启动，
您的客户端正在尝试使用错误的IP地址或端口进行连接，或
服务器访问被防火墙阻止，该防火墙拒绝＆＃34;上代表服务器/服务。鉴于此，这是不太可能的正常的做法（这些天）是防火墙到＆＃34; blackhole＆＃34;所有不必要的连接尝试。

Answer 2

在小米手机上无法在后台使用长网络连接。它会在一段时间后阻止任何网络连接。对于关键网络连接，您可以使用Firebase Cloud Messaging，它在Android系统中具有高优先级。它可以启动必要的后台工作。

Android http连接拒绝了

2 个答案: