【发布时间】：2017-08-02 07:30:45
【问题描述】：
我是 android 新手。我想使用我的服务从服务器获取 Json 数据。当我打开我的应用程序时一切正常，但是当我退出我的应用程序或当我的设备进入睡眠状态时，就会有一个 Json exception.how 我怎样才能让我的服务每次都在后台运行。请指导解决此错误。
错误：-
E/agdghdgdgdrgrdgrdg: dgdgd
W/System.err: java.net.UnknownHostException: Unable to resolve host
"podgier-
woman.000webhostapp.com": No address associated with hostname
W/System.err: at
java.net.InetAddress.lookupHostByName(InetAddress.java:457)
W/System.err: at
java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
W/System.err: at
java.net.InetAddress.getAllByName(InetAddress.java:215)
W/System.err: at
org.apache.http.conn.DefaultClientConnectionOperator.openConnection
(DefaultClientConnectionOperator.java:137)
W/System.err:at org.apache.http.impl.conn.AbstractPoolEntry.open
(AbstractPoolEntry.java:164)
W/Systemerr:at
org.apache.http.impl.conn.AbstractPooledConnAdapter.open
(AbstractPooledConnAdapter.java:119)
W/System.err: at
org.apache.http.impl.client.DefaultRequestDirector.execute
(DefaultRequestDirector.java:360)
W/System.err:at
org.apache.http.impl.client.AbstractHttpClient.execute
(AbstractHttpClient.java:555)
W/System.err:at
org.apache.http.impl.client.AbstractHttpClient.execute
(AbstractHttpClient.java:487)
W/System.err:at
org.apache.http.impl.client.AbstractHttpClient.execute
(AbstractHttpClient.java:465)
W/System.err: at com.grover.jsonp.JSONParser.makeHttpRequest
(JSONParser.java:62)
W/System.err:at com.grover.jsonp.BackgroundService$gro.doInBackground
(BackgroundService.java:50)
W/System.err: at
com.grover.jsonp.BackgroundService$gro.doInBackground
(BackgroundService.java:41)
W/System.err:at android.os.AsyncTask$2.call(AsyncTask.java:288)
W/System.err:at java.util.concurrent.FutureTask.run
(FutureTask.java:237)
W/System.err: at
android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
W/System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker
(ThreadPoolExecutor.java:1112)
W/System.err: at
java.util.concurrent.ThreadPoolExecutor
$Worker.run(ThreadPoolExecutor.java:587)
W/System.err: at java.lang.Thread.run(Thread.java:818)
W/System.err: Caused by: android.system.GaiException:
android_getaddrinfo
failed: EAI_NODATA (No address associated with hostname)
W/System.err: at libcore.io.Posix.android_getaddrinfo(Native
Method)
W/System.err: at
libcore.io.ForwardingOs.android_getaddrinfo(ForwardingOs.java:55)
W/System.err: at
java.net.InetAddress.lookupHostByName(InetAddress.java:438)
W/System.err: ... 18 more
E/Buffer Error: Error converting result java.io.IOException: Attempted
read
on closed stream.
BackgroundService.java
public class BackgroundService extends Service
{
public BackgroundService(){
}
private static String url ="https://podgier-woman.000webhostapp.com/table.php";
JSONParser jParser = new JSONParser();
ArrayList<String> bcv;
class gro extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
}
protected String doInBackground(String... args) {
java.util.List<NameValuePair> pr = new ArrayList<NameValuePair>();
JSONObject json = jParser.makeHttpRequest(url, "GET", pr);
bcv = new ArrayList<String>();
try {
JSONArray code = json.getJSONArray("code");
Log.d("list :",code.toString());
for (int i = 0; i < code.length(); i++) {
JSONObject c = code.getJSONObject(i);
bcv.add(c.getString("name"));
// adding each child node to HashMap key => value
// adding contact to contact list
JSONArray p = null;
}
}catch(JSONException e){
}
return null;
}
protected void onPostExecute(String file_url) {
Log.v("sdg","sgfdg"+record.idName);
if(record.idName < bcv.size()){
int xx= bcv.size() - record.idName;
Intent intent = new Intent(BackgroundService.this, record.class);
PendingIntent pIntent = PendingIntent.getActivity(BackgroundService.this, (int) System.currentTimeMillis(),intent, 0);
Log.d("SGsgzxv","dfgzdvv");
Notification n = new Notification.Builder(getApplicationContext())
.setContentTitle("View "+xx+" updated data")
.setContentText("data pending ")
.setSmallIcon(R.mipmap.ic_launcher)
.setContentIntent(pIntent)
.setAutoCancel(true)
.addAction(R.mipmap.ic_launcher, "call", pIntent)
.addAction(R.mipmap.ic_launcher, "More", pIntent)
.addAction(R.mipmap.ic_launcher, "and more", pIntent)
.build();
Uri so = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
n.sound = so;
NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
nm.notify(0,n);
}
record.idName = bcv.size();
bcv.clear();
}
}
private static final String TAG = "BackgroundService";
private ThreadGroup myThreads = new ThreadGroup("ServiceWorker");
@Override
public void onCreate() {
super.onCreate();
Log.v(TAG, "in onCreate()");
}
@Override
public int onStartCommand(Intent intent, int flags, int startId)
{
super.onStartCommand(intent, flags, startId);
int counter = intent.getExtras().getInt("counter");
Log.v(TAG, "in onStartCommand(), counter = " + counter +
", startId = " + startId);
new Thread(myThreads, new ServiceWorker(counter), "BackgroundService")
.start();
return START_STICKY;
}
class ServiceWorker implements Runnable
{
private int counter = -1;
public ServiceWorker(int counter) {
this.counter = counter;
}
public void run() {
final String TAG2 = "ServiceWorker:" + Thread.currentThread().getId();
// do background processing here...
try {
Log.e(TAG2, "sleeping for 5 seconds. counter = " + counter);
while(true)
{
Thread.sleep(9000);
Log.e("agdghdgdgdrgrdgrdg","dgdgd");
new gro().execute();
}
} catch (InterruptedException e) {
Log.e(TAG2, "... sleep interrupted");
}
}
}
@Override
public void onDestroy()
{
}
@Override
public IBinder onBind(Intent intent) {
Log.v(TAG, "in onBind()");
return null;
}
}
【问题讨论】：
-
使用
NOT_STICKY服务。 -
我没有看到任何 json 异常，只有
UnknownHostException，这意味着您的应用在设备休眠时无法访问互联网。这可能是由于设备屏幕关闭时 wifi 进入睡眠模式所致。您希望获取唤醒锁以防止设备休眠，但如果您在不需要唤醒锁后忘记释放唤醒锁，您的用户可能会因为您的应用程序以这种方式耗尽电池而讨厌您。 -
如果我使用移动数据可以解决这个问题吗？如果不能，那么其他应用程序在进入睡眠模式时如何使用互联网？ @VladMatvienko
-
我认为它应该适用于移动数据。其他应用可能会获得唤醒锁，并且不会让设备深度睡眠。
-
我真的很想问这样的问题