我尝试开发一个应用程序来实现来自服务器的轮询通知。我只是编写了一个应用程序，用于检查服务器中的新数据。当我启动应用程序时，它会运行一个定期检查服务器的服务。有两种情况：Main活动正在运行且应用程序正常运行。但是当我摧毁主要活动时我遇到的问题。因为当我检查旧数据和新数据之间的差异是基于主活动数组列表（数组列表用于列表视图，它的值来自服务器）。因此，如果有人可以帮助我，我有一个问题。
我的问题是：如何在主要活动被销毁时获取数组列表项的数量？即实施民意调查通知。
已更新
首先：这是Main活动类，它还包含运行的服务：
public class MainActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener{
public static boolean running;
public SwipeRefreshLayout mSwipeRefreshLayout;
ListView listView;
private PendingIntent pendingIntent;
public static ArrayAdapter<String> adapter;;
ProgressDialog progressDialog;
public static ArrayList<String> arrayList;
public static String url="http://192.168.1.103/test/index.php";
public int number;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
running=true;
Intent alarmIntent = new Intent(MainActivity.this, AlarmReceiver.class);
pendingIntent = PendingIntent.getBroadcast(MainActivity.this, 0, alarmIntent, 0);
mSwipeRefreshLayout = (SwipeRefreshLayout)findViewById(R.id.swipe_refresh_layout);
listView = (ListView)findViewById(R.id.list_item);
progressDialog=new ProgressDialog(MainActivity.this);
progressDialog.setMessage("Wait Please ");
progressDialog.show();
// ArrayAdapter arrayAdapter =new ArrayAdapter(this,android.R.layout.simple_list_item_1,)
mSwipeRefreshLayout.setOnRefreshListener(this);
mSwipeRefreshLayout.post(new Runnable() {
@Override
public void run() {
mSwipeRefreshLayout.setRefreshing(true);
LoadNews loadNews = new LoadNews(MainActivity.this, progressDialog);
loadNews.execute(url);
}
}
);
}
@Override
protected void onStop() {
this.number=10;
super.onStop();
}
public int getNumber()
{
return number;
}
@Override
protected void onDestroy() {
super.onDestroy();
running=false;
this.number=10;
// AlarmManager manager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
// manager.cancel(pendingIntent);
}
private void refreshcontent() {
LoadNews loadNews=new LoadNews(MainActivity.this,progressDialog);
loadNews.execute(url);
if(arrayList.size()==0);
// Toast.makeText(getApplicationContext(),"EMPTY",Toast.LENGTH_LONG).show();
else {
// Toast.makeText(getApplicationContext(),"NOT",Toast.LENGTH_LONG).show();
ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, arrayList);
listView.setAdapter(adapter);}
mSwipeRefreshLayout.setRefreshing(false);
// MainActivity.number_items=listView.getCount();
}
@Override
public void onRefresh() {
refreshcontent();
}
public void Setads(ArrayList<String> studentslist) {
arrayList=studentslist;
Collections.reverse(arrayList);
adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,arrayList);
listView.setAdapter(adapter);
mSwipeRefreshLayout.setRefreshing(false);
AlarmManager manager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
int interval = 20000;
Intent alarmIntent = new Intent(MainActivity.this, MyService.class);
Intent intent;
manager.setInexactRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), interval, pendingIntent);
}
public static class MyService extends IntentService {
/**
* Creates an IntentService. Invoked by your subclass's constructor.
*
* @param name Used to name the worker thread, important only for debugging.
*/
int x;
public static final String name="My_Worker_Thread";
public MyService() {
super(name);
}
/**
* Creates an IntentService. Invoked by your subclass's constructor.
*
* @param name Used to name the worker thread, important only for debugging.
*/
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// Toast.makeText(getApplicationContext(),"Test",Toast.LENGTH_LONG).show();
if (MainActivity.running)
{ Toast.makeText(getApplicationContext(),"Run",Toast.LENGTH_LONG).show();
RequestQueue requestQueue= Volley.newRequestQueue(this);
JsonArrayRequest jsonArrayRequest=new JsonArrayRequest(Request.Method.POST, url,new Response.Listener<JSONArray>(){
public void onResponse(JSONArray jsonArray) {
int temp=MainActivity.arrayList.size();
if(jsonArray.length()==temp)
{
//Toast.makeText(getApplicationContext(),"OLD",Toast.LENGTH_LONG).show();
}
else {
if (jsonArray.length() >temp && jsonArray.length() != temp) {
for (int i =temp ; i < jsonArray.length(); i++) {
try {
JSONObject jsonObject = jsonArray.getJSONObject(i);
String title=jsonObject.getString("title");
Bitmap icon = BitmapFactory.decodeResource(getResources(),
R.drawable.ic_launcher);
MainActivity.arrayList.add(0, title);
PendingIntent pi = PendingIntent.getActivity(getApplicationContext(), 0, new Intent(getApplicationContext(), MainActivity.class), 0);
// Resources r = getResources();
Notification notification = new NotificationCompat.Builder(getApplicationContext())
.setTicker("CASI")
.setSubText(jsonObject.getString("title"))
.setLargeIcon(icon)
.setContentTitle(jsonObject.getString("title"))
.setContentText(jsonObject.getString("title"))
.setContentIntent(pi)
.setAutoCancel(true)
.setSmallIcon(R.drawable.ic_launcher)
.build();
Random random = new Random();
int m = random.nextInt(9999 - 1000) + 1000;
NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
notificationManager.notify(m, notification);
} catch (JSONException e) {
e.printStackTrace();
}
}
MainActivity.adapter.notifyDataSetChanged();
}
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError volleyError) {
Log.e("Error", "Unable to parse json array");
}
});
// add json array request to the request queue
requestQueue.add(jsonArrayRequest);
}
else{
Toast.makeText(getApplicationContext(),"OFF",Toast.LENGTH_SHORT).show();
// Toast.makeText(getApplicationContext(),"Run",Toast.LENGTH_LONG).show();
RequestQueue requestQueue= Volley.newRequestQueue(this);
JsonArrayRequest jsonArrayRequest=new JsonArrayRequest(Request.Method.POST, "http://192.168.1.103/test/count.php",new Response.Listener<JSONArray>(){
public void onResponse(JSONArray jsonArray) {
// Toast.makeText(getApplicationContext(),""+temp,Toast.LENGTH_LONG).show();
if (jsonArray.length() >0) {
for (int i =0 ; i < jsonArray.length(); i++) {
try {
JSONObject jsonObject = jsonArray.getJSONObject(i);
String title=jsonObject.getString("title");
String sub=jsonObject.getString("sub");
if (Integer.parseInt(title)==Integer.parseInt(sub)){
Toast.makeText(getApplicationContext(),"No Changer",Toast.LENGTH_SHORT).show();}
else
Toast.makeText(getApplicationContext(),"New Data",Toast.LENGTH_SHORT).show();
} catch (JSONException e) {
e.printStackTrace();
}
}
// MainActivity.adapter.notifyDataSetChanged();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError volleyError) {
Log.e("Error", "Unable to parse json array");
}
});
// add json array request to the request queue
requestQueue.add(jsonArrayRequest);
// Toast.makeText(getApplicationContext(),"Nuber"+x,Toast.LENGTH_SHORT).show();
// Toast.makeText(getApplicationContext(),"Nuber"+getX(),Toast.LENGTH_SHORT).show();
}
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy() {
super.onDestroy();
}
@Override
protected void onHandleIntent(Intent intent) {
synchronized (this){
int count=0;
while (count<10) {
try {
wait(150);
count++;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
}
这是AlarmReciver类：
public class AlarmReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
// For our recurring task, we'll just display a message
//Toast.makeText(context, "I'm running", Toast.LENGTH_SHORT).show();
Intent intent2=new Intent(context,MainActivity.MyService.class);
context.startService(intent2);
}
}
这也是Load News Class，我用它来获取list-view的值并获取主要活动中的项目数：
public class LoadNews extends AsyncTask<String,Void,String> {
MainActivity mainActivity;
Context context;
ProgressDialog progressDialog;
@Override
protected void onPreExecute() {
super.onPreExecute();
}
public LoadNews(MainActivity mainActivity, ProgressDialog progressDialog)
{
this.mainActivity=mainActivity;
context=this.mainActivity.getApplicationContext();
this.progressDialog=progressDialog;
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
ArrayList<String> newstitles=new ArrayList<String>();
try {
JSONArray students=new JSONArray(s);
for (int i=0;i<students.length();i++)
{
JSONObject student= students.getJSONObject(i);
String studentname=student.getString("title");
newstitles.add(studentname);
}
// mainActivity.number=newstitles.size();
mainActivity.Setads(newstitles);
progressDialog.dismiss();
// progressDialog.dismiss();
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
protected String doInBackground(String... params) {
HttpURLConnection connection=null;
InputStream inputStream=null;
ByteArrayOutputStream content=null;
try {
URL url=new URL(params[0]);
connection= (HttpURLConnection) url.openConnection();
connection.connect();
if(connection.getResponseCode()!=HttpURLConnection.HTTP_OK)
{
Log.d("Server Erppr", connection.getResponseMessage());
return "Error in Connection to server|";
}
Log.d("Connection Error",connection.getResponseMessage());
inputStream=connection.getInputStream();
content=new ByteArrayOutputStream();
byte [] buff=new byte[2048];
long total=0;
int count=0;
while ((count=inputStream.read(buff))!=-1)
{
content.write(buff,0,count);
total=total+count;
}
}
catch (Exception ex){
ex.printStackTrace();
}
finally {
try {
inputStream.close();
connection.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
return new String(content.toByteArray());
}
}
最后，Mainifest.Xml文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="subhi.com.myapplication">
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Main22Activity"></activity>
<receiver android:name=".AlarmReceiver">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
<service android:name=".MainActivity$MyService"></service>
</application>
</manifest>
答案 0 :(得分：1)
要获取项目数，您需要在活动和服务之间建立通信。为此，您需要实现Messenger。
Messenger允许在Handler的帮助下跨进程实现基于消息的通信。
处理程序允许您发送和处理这些消息。
实施Messenger的步骤：
Service实现一个Handler，它接收来自Activity
Handler然后创建一个Messenger对象，进一步创建一个IBinder，服务返回到Activity。
Activity然后使用IBinder实例化Messenger，Activity用于向服务发送消息。
服务接收第1步中创建的处理程序中的消息。
现在让我们用一个例子来理解它：
在服务中创建一个处理程序，如下所示：
class ServiceHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
default:
super.handleMessage(msg);
}
}
}
现在，将Messenger对象和onBind（）方法添加到服务中，如上面第2步所述：
final Messenger messenger = new Messenger(new ServiceHandler());
@Override
public IBinder onBind(Intent intent) {
return messenger.getBinder();
}
在Activity中，我们将创建一个ServiceConnection来从服务中获取iBinder以实例化Messenger对象，如上面第3步所述。
Messenger messenger;
private ServiceConnection serviceConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder iBinder) {
messenger = new Messenger(iBinder);
}
public void onServiceDisconnected(ComponentName className) {
}
};
借助上面创建的ServiceConnection将服务绑定到活动：
bindService(new Intent(this, MessengerService.class), serviceConnection,
Context.BIND_AUTO_CREATE);
要从Activity向服务发送消息，请使用Messenger对象的send（）方法。
如果要在活动中接收来自服务的消息，您需要在活动中创建一个Messenger以及一个处理程序，并使用Messenger的replyTo参数接收发送给相应处理程序的消息。
更新答案：
通过Messenger发送消息执行此操作：
创建一个Bundle对象。
将数据放入Bundle对象。
将捆绑对象添加到Message对象。
通过Messenger对象的帮助将Message对象发送到Service。
示例：
Bundle bundle = new Bundle();
bundle.putFloat("key", 1.0f);
Message message = Message.obtain();
message.setData(bundle);
messenger.send(message);
有关详细信息，请访问以下链接：
http://developer.android.com/guide/components/bound-services.html