轉載至:http://blog.csdn.net/dawanganban/article/details/9763319
在Android中,Activity主要負責前臺頁面的展示,Service主要負責需要長期運行的任務,所以在我們實際開發中,就會常常遇到Activity與Service之間的通信,我們一般在Activity中啓動後臺Service,通過Intent來啓動,Intent中我們可以傳遞數據給Service,而當我們Service執行某些操作之後想要更新UI線程,我們應該怎麼做呢?接下來我就介紹兩種方式來實現Service與Activity之間的通信問題
- 通過Binder對象
當Activity通過調用bindService(Intent service, ServiceConnection conn,int flags),我們可以得到一個Service的一個對象實例,然後我們就可以訪問Service中的方法,我們還是通過一個例子來理解一下吧,一個模擬下載的小例子,帶大家理解一下通過Binder通信的方式
首先我們新建一個工程Communication,然後新建一個Service類
- <span style="font-family:System;">package com.example.communication;
- import android.app.Service;
- import android.content.Intent;
- import android.os.Binder;
- import android.os.IBinder;
- public class MsgService extends Service {
- /**
- * 進度條的最大值
- */
- public static final int MAX_PROGRESS = 100;
- /**
- * 進度條的進度值
- */
- private int progress = 0;
- /**
- * 增加get()方法,供Activity調用
- * @return 下載進度
- */
- public int getProgress() {
- return progress;
- }
- /**
- * 模擬下載任務,每秒鐘更新一次
- */
- public void startDownLoad(){
- new Thread(new Runnable() {
- @Override
- public void run() {
- while(progress < MAX_PROGRESS){
- progress += 5;
- try {
- Thread.sleep(1000);
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
- }).start();
- }
- /**
- * 返回一個Binder對象
- */
- @Override
- public IBinder onBind(Intent intent) {
- return new MsgBinder();
- }
- public class MsgBinder extends Binder{
- /**
- * 獲取當前Service的實例
- * @return
- */
- public MsgService getService(){
- return MsgService.this;
- }
- }
- }</span>
- Intent intent = new Intent("com.example.communication.MSG_ACTION");
- bindService(intent, conn, Context.BIND_AUTO_CREATE);
通過上面的代碼我們就在Activity綁定了一個Service,上面需要一個ServiceConnection對象,它是一個接口,我們這裏使用了匿名內部類
- <span style="font-family:System;"> ServiceConnection conn = new ServiceConnection() {
- @Override
- public void onServiceDisconnected(ComponentName name) {
- }
- @Override
- public void onServiceConnected(ComponentName name, IBinder service) {
- //返回一個MsgService對象
- msgService = ((MsgService.MsgBinder)service).getService();
- }
- };</span>
在onServiceConnected(ComponentName name, IBinder service) 回調方法中,返回了一個MsgService中的Binder對象,我們可以通過getService()方法來得到一個MsgService對象,然後可以調用MsgService中的一些方法,Activity的代碼如下
- <span style="font-family:System;">package com.example.communication;
- import android.app.Activity;
- import android.content.ComponentName;
- import android.content.Context;
- import android.content.Intent;
- import android.content.ServiceConnection;
- import android.os.Bundle;
- import android.os.IBinder;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.widget.Button;
- import android.widget.ProgressBar;
- public class MainActivity extends Activity {
- private MsgService msgService;
- private int progress = 0;
- private ProgressBar mProgressBar;
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- //綁定Service
- Intent intent = new Intent("com.example.communication.MSG_ACTION");
- bindService(intent, conn, Context.BIND_AUTO_CREATE);
- mProgressBar = (ProgressBar) findViewById(R.id.progressBar1);
- Button mButton = (Button) findViewById(R.id.button1);
- mButton.setOnClickListener(new OnClickListener() {
- @Override
- public void onClick(View v) {
- //開始下載
- msgService.startDownLoad();
- //監聽進度
- listenProgress();
- }
- });
- }
- /**
- * 監聽進度,每秒鐘獲取調用MsgService的getProgress()方法來獲取進度,更新UI
- */
- public void listenProgress(){
- new Thread(new Runnable() {
- @Override
- public void run() {
- while(progress < MsgService.MAX_PROGRESS){
- progress = msgService.getProgress();
- mProgressBar.setProgress(progress);
- try {
- Thread.sleep(1000);
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
- }).start();
- }
- ServiceConnection conn = new ServiceConnection() {
- @Override
- public void onServiceDisconnected(ComponentName name) {
- }
- @Override
- public void onServiceConnected(ComponentName name, IBinder service) {
- //返回一個MsgService對象
- msgService = ((MsgService.MsgBinder)service).getService();
- }
- };
- @Override
- protected void onDestroy() {
- unbindService(conn);
- super.onDestroy();
- }
- }</span><span style="font-family: simsun;">
- </span>
上面的代碼就完成了在Service更新UI的操作,可是你發現了沒有,我們每次都要主動調用getProgress()來獲取進度值,然後隔一秒在調用一次getProgress()方法,你會不會覺得很被動呢?可不可以有一種方法當Service中進度發生變化主動通知Activity,答案是肯定的,我們可以利用回調接口實現Service的主動通知,不理解回調方法的可以看看http://blog.csdn.net/xiaanming/article/details/8703708
新建一個回調接口
- public interface OnProgressListener {
- void onProgress(int progress);
- }
- <span style="font-family:System;">package com.example.communication;
- import android.app.Service;
- import android.content.Intent;
- import android.os.Binder;
- import android.os.IBinder;
- public class MsgService extends Service {
- /**
- * 進度條的最大值
- */
- public static final int MAX_PROGRESS = 100;
- /**
- * 進度條的進度值
- */
- private int progress = 0;
- /**
- * 更新進度的回調接口
- */
- private OnProgressListener onProgressListener;
- /**
- * 註冊回調接口的方法,供外部調用
- * @param onProgressListener
- */
- public void setOnProgressListener(OnProgressListener onProgressListener) {
- this.onProgressListener = onProgressListener;
- }
- /**
- * 增加get()方法,供Activity調用
- * @return 下載進度
- */
- public int getProgress() {
- return progress;
- }
- /**
- * 模擬下載任務,每秒鐘更新一次
- */
- public void startDownLoad(){
- new Thread(new Runnable() {
- @Override
- public void run() {
- while(progress < MAX_PROGRESS){
- progress += 5;
- //進度發生變化通知調用方
- if(onProgressListener != null){
- onProgressListener.onProgress(progress);
- }
- try {
- Thread.sleep(1000);
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
- }).start();
- }
- /**
- * 返回一個Binder對象
- */
- @Override
- public IBinder onBind(Intent intent) {
- return new MsgBinder();
- }
- public class MsgBinder extends Binder{
- /**
- * 獲取當前Service的實例
- * @return
- */
- public MsgService getService(){
- return MsgService.this;
- }
- }
- }</span>
- <span style="font-family:System;">package com.example.communication;
- import android.app.Activity;
- import android.content.ComponentName;
- import android.content.Context;
- import android.content.Intent;
- import android.content.ServiceConnection;
- import android.os.Bundle;
- import android.os.IBinder;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.widget.Button;
- import android.widget.ProgressBar;
- public class MainActivity extends Activity {
- private MsgService msgService;
- private ProgressBar mProgressBar;
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- //綁定Service
- Intent intent = new Intent("com.example.communication.MSG_ACTION");
- bindService(intent, conn, Context.BIND_AUTO_CREATE);
- mProgressBar = (ProgressBar) findViewById(R.id.progressBar1);
- Button mButton = (Button) findViewById(R.id.button1);
- mButton.setOnClickListener(new OnClickListener() {
- @Override
- public void onClick(View v) {
- //開始下載
- msgService.startDownLoad();
- }
- });
- }
- ServiceConnection conn = new ServiceConnection() {
- @Override
- public void onServiceDisconnected(ComponentName name) {
- }
- @Override
- public void onServiceConnected(ComponentName name, IBinder service) {
- //返回一個MsgService對象
- msgService = ((MsgService.MsgBinder)service).getService();
- //註冊回調接口來接收下載進度的變化
- msgService.setOnProgressListener(new OnProgressListener() {
- @Override
- public void onProgress(int progress) {
- mProgressBar.setProgress(progress);
- }
- });
- }
- };
- @Override
- protected void onDestroy() {
- unbindService(conn);
- super.onDestroy();
- }
- }
- </span>
- 通過broadcast(廣播)的形式
當我們的進度發生變化的時候我們發送一條廣播,然後在Activity的註冊廣播接收器,接收到廣播之後更新ProgressBar,代碼如下
- package com.example.communication;
- <span style="font-family:System;">
- 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.view.View;
- import android.view.View.OnClickListener;
- import android.widget.Button;
- import android.widget.ProgressBar;
- public class MainActivity extends Activity {
- private ProgressBar mProgressBar;
- private Intent mIntent;
- private MsgReceiver msgReceiver;
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- //動態註冊廣播接收器
- msgReceiver = new MsgReceiver();
- IntentFilter intentFilter = new IntentFilter();
- intentFilter.addAction("com.example.communication.RECEIVER");
- registerReceiver(msgReceiver, intentFilter);
- mProgressBar = (ProgressBar) findViewById(R.id.progressBar1);
- Button mButton = (Button) findViewById(R.id.button1);
- mButton.setOnClickListener(new OnClickListener() {
- @Override
- public void onClick(View v) {
- //啓動服務
- mIntent = new Intent("com.example.communication.MSG_ACTION");
- startService(mIntent);
- }
- });
- }
- @Override
- protected void onDestroy() {
- //停止服務
- stopService(mIntent);
- //註銷廣播
- unregisterReceiver(msgReceiver);
- super.onDestroy();
- }
- /**
- * 廣播接收器
- * @author len
- *
- */
- public class MsgReceiver extends BroadcastReceiver{
- @Override
- public void onReceive(Context context, Intent intent) {
- //拿到進度,更新UI
- int progress = intent.getIntExtra("progress", 0);
- mProgressBar.setProgress(progress);
- }
- }
- }
- </span>
- <span style="font-family:System;">package com.example.communication;
- import android.app.Service;
- import android.content.Intent;
- import android.os.IBinder;
- public class MsgService extends Service {
- /**
- * 進度條的最大值
- */
- public static final int MAX_PROGRESS = 100;
- /**
- * 進度條的進度值
- */
- private int progress = 0;
- private Intent intent = new Intent("com.example.communication.RECEIVER");
- /**
- * 模擬下載任務,每秒鐘更新一次
- */
- public void startDownLoad(){
- new Thread(new Runnable() {
- @Override
- public void run() {
- while(progress < MAX_PROGRESS){
- progress += 5;
- //發送Action爲com.example.communication.RECEIVER的廣播
- intent.putExtra("progress", progress);
- sendBroadcast(intent);
- try {
- Thread.sleep(1000);
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
- }).start();
- }
- @Override
- public int onStartCommand(Intent intent, int flags, int startId) {
- startDownLoad();
- return super.onStartCommand(intent, flags, startId);
- }
- @Override
- public IBinder onBind(Intent intent) {
- return null;
- }
-
總結:
-
Activity調用bindService
(Intent service, ServiceConnection conn, int flags)方法,得到Service對象的一個引用,這樣Activity可以直接調用到Service中的方法,如果要主動通知Activity,我們可以利用回調方法
- Service向Activity發送消息,可以使用廣播,當然Activity要註冊相應的接收器。比如Service要向多個Activity發送同樣的消息的話,用這種方法就更好
-
Activity調用bindService
(Intent service, ServiceConnection conn, int flags)方法,得到Service對象的一個引用,這樣Activity可以直接調用到Service中的方法,如果要主動通知Activity,我們可以利用回調方法