Andriod學習--Service使用

      今天主要學習一下Android四大組件的Service用法。

一、Service的啓動與停止

1、定義一個服務MyService繼承Service

package com.example.servicetest;

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

public class MyService extends Service {
    public MyService() {
    }

    @Override
    public IBinder onBind(Intent intent) {
        return 0;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Log.d("MyService", "---onCreate()-------");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.d("MyService", "---onStartCommand()-------");
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.d("MyService", "---onDestroy()-------");
    }

}

複寫其中onCreate()、onStartCommand(）、onDestroy()方法

2、佈局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/start_service"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Start Service"/>

    <Button
        android:id="@+id/stop_service"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Stop Service"/>

</LinearLayout>

3、主MainActivity

package com.example.servicetest;

import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button startService = (Button) findViewById(R.id.start_service);
        Button stopService = (Button) findViewById(R.id.stop_service);
        startService.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent startIntent = new Intent(MainActivity.this, MyService.class);
                startService(startIntent);
            }
        });
        stopService.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent stopIntent = new Intent(MainActivity.this, MyService.class);
                stopService(stopIntent);
            }
        });
    }
}

AndroidStudio 在AndroidManifest.xml中自動爲Service註冊

運行結果：

點擊startService按鈕

點擊stopService按鈕

二、活動與服務進行通信

希望在MyServcie中提供一個下載功能，然後在活動中可以決定何時開始下載，以及隨時查看下載進度。

在MyService中修改

package com.example.servicetest;

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

public class MyService extends Service {
    ......

    private DownloadBinder mBinder = new DownloadBinder();

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

    class DownloadBinder extends Binder{

        public void startDownload(){
            Log.d("MyService", "---startDownload() executed-------");
        }

        public int getProgress(){
            Log.d("MyService", "---getProgress() executed-------");
            return 0;
        }
    }


}

在佈局文件中再增加兩個button

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    ......

    <Button
        android:id="@+id/bind_service"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Bind Service"/>

    <Button
        android:id="@+id/unbind_service"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Unbind Service"/>

</LinearLayout>

在MainActivity中修改

public class MainActivity extends AppCompatActivity {

    private MyService.DownloadBinder downloadBinder;
    private ServiceConnection connection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            downloadBinder = (MyService.DownloadBinder) service;
            downloadBinder.startDownload();
            downloadBinder.getProgress();
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ......
        Button bindService = (Button) findViewById(R.id.bind_service);
        Button unbindService = (Button) findViewById(R.id.unbind_service);
        bindService.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent bindIntent = new Intent(MainActivity.this, MyService.class);
                bindService(bindIntent, connection, BIND_AUTO_CREATE); //綁定服務
            }
        });
        unbindService.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                unbindService(connection); //解綁服務
            }
        });
    }
}

運行效果

點擊bindService按鈕

注意：當調用了startService()又調用了stopService()方法，必須同時調用stopService()和unbindServicce()，onDestry()方法才能執行