android - 即使应用程序关闭，也可以从后台服务更新 Activity 中的 textview

Question

即使应用已关闭，我也想在调用网络服务后每 5 秒更新一次 UI。我创建了一个服务并使用广播接收器从服务器获取数据，但是当应用程序关闭时，服务器的最后响应应该更新，但是当我打开应用程序时，最后响应数据没有更新。

下面是代码 fragment

MainActivity.java

import java.text.DateFormat;

import org.json.JSONArray;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v4.content.LocalBroadcastManager;
import android.widget.TextView;

public class MainActivity extends Activity {

TextView name1, name;

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

    setContentView(R.layout.activity_main);

    name = (TextView)findViewById(R.id.name);
    name1 = (TextView)findViewById(R.id.name1);


    startService(new Intent(MainActivity.this, YourService.class));

}

private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        // Get extra data included in the Intent
        String nameStr = intent.getStringExtra("name");
        String name1Str = intent.getStringExtra("name1");
        name.setText(nameStr);
        name1.setText(name1Str);
    }
};

@Override
protected void onResume()
{
   super.onResume();
   //registerReceiver(statusReceiver,mIntent);
   LocalBroadcastManager.getInstance(MainActivity.this).registerReceiver(
           mMessageReceiver, new IntentFilter("UIValues"));
 }

  @Override
  protected void onPause() {

   LocalBroadcastManager.getInstance(MainActivity.this).unregisterReceiver(mMessageReceiver);
   super.onPause();
  }
 }

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >

<TextView
    android:id="@+id/name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="20dp"
    android:layout_marginTop="12dp"
    android:hint="md5"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textSize="20sp" />

<TextView
    android:id="@+id/name1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="20dp"
    android:layout_marginTop="12dp"
    android:hint="name"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textSize="20sp" />

 </LinearLayout>

YourService.java

import learn2crack.asynctask.library.JSONParser;

import android.app.Service;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.support.v4.content.LocalBroadcastManager;
import android.util.Log;

public class YourService extends Service {

private static final String TAG = "Your Service";

private final Handler handler = new Handler(){
    @Override
    public void handleMessage(Message msg) {

    }
};
@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public void onCreate() {
    Log.d(TAG, "onCreate");

}

@Override
public void onDestroy() {
    super.onDestroy();
    handler.removeCallbacks(sendUpdatesToUI);   
}
 private Runnable sendUpdatesToUI = new Runnable() {
        public void run() {
             new JSONParse().execute();

            /// Any thing you want to do put the code here like web service procees it will run in ever 1 second
            handler.postDelayed(this, 5000); // 5 seconds
        }
 };
@Override
public void onStart(Intent intent, int startid) {

    handler.removeCallbacks(sendUpdatesToUI);
    handler.postDelayed(sendUpdatesToUI, 1000);//1 second       
    Log.d(TAG, "onStart");
}

 private class JSONParse extends AsyncTask<String, String, JSONObject> {
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected JSONObject doInBackground(String... args) {
        JSONParser jParser = new JSONParser();

        // Getting JSON from URL
        JSONObject json = jParser.getJSONFromUrl(url);  // server url
        return json;
    }
     @Override
     protected void onPostExecute(JSONObject json) {
         try {
            if(json != null){

             JSONObject reader = new JSONObject(json.toString());
             String name = reader.getString("name");
             String name1 = reader.getString("name1");
              Intent intent = new Intent("UIValues");
                intent.putExtra("name", name);
                intent.putExtra("name1", name1);
                LocalBroadcastManager.getInstance(getApplicationContext()).sendBroadcast(intent);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
     }
}

JSONParser.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

// constructor
public JSONParser() {

}

public JSONObject getJSONFromUrl(String url) {

    // Making HTTP request
    try {
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        is = httpEntity.getContent();           

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "iso-8859-1"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
        is.close();
        json = sb.toString();
    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }

    // try parse the string to a JSON object
    try {
        jObj = new JSONObject(json);
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }

    // return JSON String
    return jObj;

    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.asynctask"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="15"/>
<uses-permission android:name="android.permission.INTERNET" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.asynctask.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <service android:name="com.asynctask.YourService"></service>

</application>

</manifest>

谁能帮我解决这个问题。提前致谢

Answer 1

您可能应该将最后一个响应保存在持久性存储(文件、共享首选项)中，并在应用程序打开后简单地读取它并显示最后一个响应。