Question

是一个新手android开发人员。我试图从Android中的服务调用URL（URL返回json数据）。我已经能够创建一个能够每10或20秒触发一次TOAST通知的服务。你能告诉我如何在服务中实现URL调用，这样我就可以在固定的时间间隔触发服务时从URL中检索数据。下面是我添加URL调用后停止工作的代码。

MainActivity.java：

package com.example.android.myservice;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.Application;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import java.util.Calendar;

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(System.currentTimeMillis());
        calendar.add(Calendar.SECOND, 10); // first time
        long frequency= 10 * 1000;
        Intent i = new Intent(getBaseContext(), MyService.class);
        PendingIntent recurring = PendingIntent.getService(getBaseContext(), 0, i, PendingIntent.FLAG_CANCEL_CURRENT);
        AlarmManager alarms = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
        alarms.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), frequency, recurring);

        finish();       
    }

}

MyService.java：

package com.example.android.myservice;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class MyService extends Service {

    public MyService() {
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {




        HttpURLConnection urlConnection = null;
        BufferedReader reader = null;

        // Will contain the raw JSON response as a string.
        String forecastJsonStr = null;

        try {

            URL url = new URL("http://api.openweathermap.org/data/2.5/forecast/daily?q=94043&mode=json&units=metric&cnt=7&appid=2de143494c0b295cca9337e1e96b00e0");

            // Create the request to OpenWeatherMap, and open the connection
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();

            // Read the input stream into a String
            InputStream inputStream = urlConnection.getInputStream();
            StringBuffer buffer = new StringBuffer();

            reader = new BufferedReader(new InputStreamReader(inputStream));

            String line;
            while ((line = reader.readLine()) != null) {

                buffer.append(line + "\n");
            }

            forecastJsonStr = buffer.toString();

        } catch (IOException e) {
            Log.e("PlaceholderFragment", "Error ", e);

        }
        Toast.makeText(this,"Service started - "+forecastJsonStr, Toast.LENGTH_LONG).show();


        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Toast.makeText(this,"Service started", Toast.LENGTH_LONG).show();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        return null;
    }
}

AndroidManifest：

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        >
        <uses-permission android:name="android.permission.INTERNET"/>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <service
            android:name=".MyService"
            android:enabled="true"
            android:exported="true"
            android:permission="android.permission.INTERNET"></service>
    </application>

</manifest>

Answer 1

INTERNET权限需要超出application标记：

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

    <!-- Move the permission here, outside of the application tag: -->
    <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>

        <service
            android:name=".MyService"
            android:enabled="true"
            android:exported="true"
            android:permission="android.permission.INTERNET"></service>
    </application>

</manifest>

来自Android服务的URL调用

1 个答案: