[Andorid] Service 範例-背景執行/無UI

要做一個Service要先了解,service無法自己啟動,必須要靠startService()才能啟動。

同樣的啟動後也必須要使用stopService()關閉。

在這邊需要注意的有幾點

1) startService()

2) stopService()

3) AndroidManiFest.xml增加service權限


第一點為開啟service必要條件,當然你要new一個intent

所以就是:

Intent intent = new Intent(MainActivity.this,service_class.class);
startService(intent);

MainActivity為你目前的class,service_class則是另外開的java檔(那邊則是寫service做的事情)


第二點跟第一點很類似,只有差在start / stop的差別

Intent intent = new Intent(MainActivity.this,service_class.class);
stopService(intent);

第三點就是你需要在Android ManiFest.xml裡面新增權限

否則跑起來會有

"

Unable to start service Intent: not found

"
這樣的錯誤訊息出現

好了,總結上面 MainActivity該如何寫?

package com.example.service_nonui_demo;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent intent = new Intent(MainActivity.this,service_class.class);
startService(intent);
}
@Override
public void onPause(){
super.onPause();
Intent intent = new Intent(MainActivity.this,service_class.class);
stopService(intent);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}

/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {

public PlaceholderFragment() {
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}

}

Service部分

package com.example.service_nonui_demo;

import android.app.Service;

import android.content.Intent;

import android.os.IBinder;

import android.widget.Toast;

public class service_class extends Service{

@Override

public IBinder onBind(Intent arg0) {

// TODO Auto-generated method stub

return null;

}

@Override

public void onCreate() {

// TODO Auto-generated method stub

super.onCreate();

}

 

@Override

public void onStart(Intent intent, int startId) {

Toast.makeText(this, "Service start", Toast.LENGTH_SHORT).show();

}

public void onDestroy(){

super.onDestroy();

Toast.makeText(this, "Service stop", Toast.LENGTH_SHORT).show();

}

}

(記得要extends Service!)

Android ManiFest.xml部分

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.service_nonui_demo"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="19" />

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name="com.example.service_nonui_demo.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="service_class"></service>

    </application>

</manifest>

記得要新增紅色字的這一行

如此一來,service就可以啟動了!

service在onStart()的地方開始運作,所以如果要做任何動作,可以寫在裡面喔!

範例只是做一個toast(跳出訊息)而已。

附上範例檔案　**點這裡下載**

End