Android學習(4)

系出名門android(4) - 活動(Activity),服務(Service),廣播(Broadcast),廣播接收器(BroadcastReceiver)

介紹

在 android 中使用 Activity, Service, Broadcast, BroadcastReceiver

活動(Activity) - 用於表現功能

服務(Service) - 相當於後台運行的 Activity

廣播(Broadcast) - 用於發送廣播

廣播接收器(BroadcastReceiver) - 用於接收廣播

Intent - 用於連接以上各個組件，並在其間傳遞消息

1、演示 Activity 的基本用法，一個 Activity 啟動另一個 Activity，啟動另一個 Activity 時為其傳遞參數，被啟動的 Activity 返回參數給啟動者的 Activity

Main.Java

package com.webabcd.activity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.VIEw;
import android.widget.Button;
import android.widget.TextVIEw;

public class Main extends Activity {

    TextVIEw txt;

   
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentVIEw(R.layout.main);

        txt = (TextView) this.findVIEwById(R.id.txt);
        txt.setText("Activity 1");

        Button btn = (Button) this.findVIEwById(R.id.btn);
        btn.setText("啟動另一個Activity");
        btn.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(VIEw v) {

                // 實例化 Intent，指定需要啟動的 Activity
                Intent intent = new Intent();
                intent.setClass(Main.this, MyActivity.class);

                // 實例化 Bundle，設置需要傳遞的參數
                Bundle bundle = new Bundle();
                bundle.putString("name", "webabcd");
                bundle.putDouble("salary", 100.13);

                // 將需要傳遞的參數賦值給 Intent 對象
                intent.putExtras(bundle);

                // startActivity(intent); // 啟動指定的 Intent（不等待返回結果）
                // Main.this.finish();

                // 啟動指定的 Intent，並等待返回結果
                // 其中第二個參數如果大於等於零，則返回結果時會回調 onActivityResult() 方法
                startActivityForResult(intent, 0);         });

        Log.d("MyDebug", "onCreate");
    }

    // 被啟動的 Activity 返回結果時的回調函數
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == Activity.RESULT_OK){
            Bundle bundle = data.getExtras();

            String name = bundle.getString("name");
            double salary = bundle.getDouble("salary");

            txt.setText("Activity 1" + "\n名字：" + name + "\n薪水：" + String.valueOf(salary));     }

    @Override
    protected void onStart() {
        // TODO Auto-generated method stub
        super.onStart();

        Log.d("MyDebug", "onStart");
    }

    @Override
    protected void onStop() {
        // TODO Auto-generated method stub
        super.onStop();

        Log.d("MyDebug", "onStop");
    }

    @Override
    protected void onRestart() {
        // TODO Auto-generated method stub
        super.onRestart();

        Log.d("MyDebug", "onRestart");
    }

    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();

        Log.d("MyDebug", "onPause");
    }

    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();

        Log.d("MyDebug", "onResume");
    }

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();

        Log.d("MyDebug", "onDestroy"); }

MyActivity.Java

package com.webabcd.activity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.VIEw;
import android.widget.Button;
import android.widget.TextVIEw;

// 被另一個 Activity 所啟動的 Activity
public class MyActivity extends Activity {

    Intent intent;

   
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentVIEw(R.layout.main2);

        // 獲取啟動者傳遞過來的參數
        intent = this.getIntent();
        Bundle bundle = intent.getExtras();       
        String name = bundle.getString("name");
        double salary = bundle.getDouble("salary");

        TextView txt = (TextView) this.findVIEwById(R.id.txt);
        txt.setText("Activity 2" + "\n名字：" + name + "\n薪水：" + String.valueOf(salary));

        Button btn = (Button) this.findVIEwById(R.id.btn);
        btn.setText("返回前一個Activity");
        btn.setOnClickListener(new Button.OnClickListener() {
            public void onClick(VIEw v) {                 MyActivity.this.setResult(Activity.RESULT_OK, intent);
                MyActivity.this.finish();         }); }

androidManifest.XML

<?XML version="1.0" encoding="utf-8"?>
<manifest XMLns:android="http://schemas.android.com/apk/res/android"
    package="com.webabcd.activity" android:versionCode="1"
    android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".Main" android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <!--
            如果有需要用到的 Activity ，則都要在這裡做相應的配置
        -->
        <activity android:name=".MyActivity" android:label="Activity 2" />
    </application>
    <uses-sdk android:minSdkVersion="3" />
</manifest>

2、Service, Broadcast, BroadcastReceiver 的演示

Main.Java

package com.webabcd.service;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.VIEw;
import android.view.VIEw.OnClickListener;
import android.widget.TextVIEw;

public class Main extends Activity implements OnClickListener {

    private TextVIEw txtMsg;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentVIEw(R.layout.main);

        setTitle("android 之 service");

        this.findVIEwById(R.id.btnStart).setOnClickListener(this);
        this.findVIEwById(R.id.btnStop).setOnClickListener(this);
        this.findVIEwById(R.id.btnBind).setOnClickListener(this);
        this.findVIEwById(R.id.btnUnbind).setOnClickListener(this);

        txtMsg = (TextView)this.findVIEwById(R.id.txtMsg);

        // 實例化自定義的 BroadcastReceiver
        receiver = new UpdateReceiver();
        IntentFilter filter = new IntentFilter();
        // 為 BroadcastReceiver 指定 action ，使之用於接收同 action 的廣播
        filter.addAction("com.webabcd.service.msg");

        // 以編程方式注冊  BroadcastReceiver 。配置方式注冊 BroadcastReceiver 的例子見 androidManifest.XML 文件
        // 一般在 OnStart 時注冊，在 OnStop 時取消注冊
        this.registerReceiver(receiver, filter);
        // this.unregisterReceiver(receiver);

    }

    @Override
    public void onClick(VIEw v) {
        Intent intent = new Intent(Main.this, MyService.class);
        switch (v.getId()) {
        case R.id.btnStart:
            this.startService(intent);
            break;
        case R.id.btnStop:
            this.stopService(intent);
            break;
        case R.id.btnBind:
            this.bindService(intent, conn, Context.BIND_AUTO_CREATE);
            break;
        case R.id.btnUnbind:
            this.unbindService(conn);
            break;     }

    // bindService() 所需的 ServiceConnection 對象
    private ServiceConnection conn = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName className, IBinder service) {

        }
        @Override
        public void onServiceDisconnected(ComponentName className) {

        }
    };

    private String msg="";
    private UpdateReceiver receiver;
    // 實現一個 BroadcastReceiver，用於接收指定的 Broadcast
    public class UpdateReceiver extends BroadcastReceiver{

        @Override
        public void onReceive(Context context, Intent intent) {
            msg = intent.getStringExtra("msg");

            txtMsg.append(msg + "\n");
        }

    }
}

MyService.Java

package com.webabcd.service;

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

// 演示 Service 的生命周期。具體信息運行程序後在 LogCat 中查看
public class MyService extends Service {

    @Override
    public IBinder onBind(Intent intent) {

        Log.d("MyDebug", "onBind");
        sendMsg("onBind");

        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();

        Log.d("MyDebug", "onCreate");
        sendMsg("onCreate");
    }

    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();

        Log.d("MyDebug", "onDestroy");
        sendMsg("onDestroy");
    }

    @Override
    public void onRebind(Intent intent) {
        // TODO Auto-generated method stub
        super.onRebind(intent);

        Log.d("MyDebug", "onRebind");
        sendMsg("onRebind");
    }

    @Override
    public void onStart(Intent intent, int startId) {
        super.onStart(intent, startId);

        Log.d("MyDebug", "onStart");
        sendMsg("onStart");
    }

    @Override
    public boolean onUnbind(Intent intent) {

        Log.d("MyDebug", "onUnbind");
        sendMsg("onUnbind");

        // TODO Auto-generated method stub
        return super.onUnbind(intent);
    }

    // 發送廣播信息
    private void sendMsg(String msg){
        // 指定廣播目標的 action （注：指定了此 action 的 receiver 會接收此廣播）
        Intent intent = new Intent("com.webabcd.service.msg");         intent.putExtra("msg", msg);         this.sendBroadcast(intent); }

MyBootReceiver.Java

package com.webabcd.service;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;

public class MyBootReceiver extends BroadcastReceiver {

    // 用於接收滿足條件的 Broadcast（相應的 Broadcast 的注冊信息詳見 androidManifest.XML ，當系統啟動完畢後會調用這個廣播接收器）
    @Override
    public void onReceive(Context arg0, Intent arg1) {
        Log.d("MyDebug", "onReceive");

        // 啟動服務
        Intent service = new Intent(arg0, MyService.class);
        arg0.startService(service);
    }

androidManifest.XML

<?XML version="1.0" encoding="utf-8"?>
<manifest XMLns:android="http://schemas.android.com/apk/res/android"
    package="com.webabcd.service" android:versionCode="1"
    android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".Main" android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <!--
            如果有需要用到的 service ，則都要在這裡做相應的配置
        -->
        <service android:name=".MyService"></service>

        <!--
            注冊一個 BroadcastReceiver
            其 intent-filter 為 android.intent.action.BOOT_COMPLETED（用於接收系統啟動完畢的 Broadcast）
        -->
        <receiver android:name=".MyBootReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
            </intent-filter>
        </receiver>
    </application>

    <!--
        接受系統啟動完畢的 Broadcast 的權限
    -->
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
    <uses-sdk android:minSdkVersion="3" />
</manifest>

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