Broadcast Receiver 使用入門

 

介紹 
在 Android 中使用 Activity, Service, Broadcast, BroadcastReceiver 
活動(Activity) - 用於表現功能  
服務(Service) - 相當於後臺運行的 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 啓動另一個 Activity，啓動另一個 Activity 時爲其傳遞參數，被啓動的 Activity 返回參數給啓動者的 Activity 

Java代碼  

1. Main.java 2. 3. 代碼 4. package com.webabcd.activity; 5. 6. import android.app.Activity; 7. import android.content.Intent; 8. import android.os.Bundle; 9. import android.util.Log; 10. import android.view.View; 11. import android.widget.Button; 12. import android.widget.TextView; 13. 14. public class Main extends Activity { 15. 16. TextView txt; 17. 18. /** Called when the activity is first created. */ 19. @Override 20. public void onCreate(Bundle savedInstanceState) { 21. super.onCreate(savedInstanceState); 22. this.setContentView(R.layout.main); 23. 24. txt = (TextView) this.findViewById(R.id.txt); 25. txt.setText("Activity 1"); 26. 27. Button btn = (Button) this.findViewById(R.id.btn); 28. btn.setText("啓動另一個Activity"); 29. btn.setOnClickListener(new Button.OnClickListener() { 30. @Override 31. public void onClick(View v) { 32. 33. // 實例化 Intent，指定需要啓動的 Activity 34. Intent intent = new Intent(); 35. intent.setClass(Main.this, MyActivity.class); 36. 37. // 實例化 Bundle，設置需要傳遞的參數 38. Bundle bundle = new Bundle(); 39. bundle.putString("name", "webabcd"); 40. bundle.putDouble("salary", 100.13); 41. 42. // 將需要傳遞的參數賦值給 Intent 對象 43. intent.putExtras(bundle); 44. 45. // startActivity(intent); // 啓動指定的 Intent（不等待返回結果） 46. // Main.this.finish(); 47. 48. // 啓動指定的 Intent，並等待返回結果 49. // 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 50. startActivityForResult(intent, 0); 51. } 52. }); 53. 54. Log.d("MyDebug", "onCreate"); 55. } 56. 57. // 被啓動的 Activity 返回結果時的回調函數 58. @Override 59. protected void onActivityResult(int requestCode, int resultCode, Intent data) { 60. if (resultCode == Activity.RESULT_OK){ 61. Bundle bundle = data.getExtras(); 62. 63. String name = bundle.getString("name"); 64. double salary = bundle.getDouble("salary"); 65. 66. txt.setText("Activity 1" + "/n名字：" + name + "/n薪水：" + String.valueOf(salary)); 67. } 68. } 69. 70. @Override 71. protected void onStart() { 72. // TODO Auto-generated method stub 73. super.onStart(); 74. 75. Log.d("MyDebug", "onStart"); 76. } 77. 78. @Override 79. protected void onStop() { 80. // TODO Auto-generated method stub 81. super.onStop(); 82. 83. Log.d("MyDebug", "onStop"); 84. } 85. 86. @Override 87. protected void onRestart() { 88. // TODO Auto-generated method stub 89. super.onRestart(); 90. 91. Log.d("MyDebug", "onRestart"); 92. } 93. 94. @Override 95. protected void onPause() { 96. // TODO Auto-generated method stub 97. super.onPause(); 98. 99. Log.d("MyDebug", "onPause"); 100. } 101. 102. @Override 103. protected void onResume() { 104. // TODO Auto-generated method stub 105. super.onResume(); 106. 107. Log.d("MyDebug", "onResume"); 108. } 109. 110. @Override 111. protected void onDestroy() { 112. // TODO Auto-generated method stub 113. super.onDestroy(); 114. 115. Log.d("MyDebug", "onDestroy"); 116. } 117. } 118. 119. MyActivity.java 120. 121. 代碼 122. package com.webabcd.activity; 123. 124. import android.app.Activity; 125. import android.content.Intent; 126. import android.os.Bundle; 127. import android.view.View; 128. import android.widget.Button; 129. import android.widget.TextView; 130. 131. // 被另一個 Activity 所啓動的 Activity 132. public class MyActivity extends Activity { 133. 134. Intent intent; 135. 136. /** Called when the activity is first created. */ 137. @Override 138. public void onCreate(Bundle savedInstanceState) { 139. super.onCreate(savedInstanceState); 140. this.setContentView(R.layout.main2); 141. 142. // 獲取啓動者傳遞過來的參數 143. intent = this.getIntent(); 144. Bundle bundle = intent.getExtras(); 145. String name = bundle.getString("name"); 146. double salary = bundle.getDouble("salary"); 147. 148. TextView txt = (TextView) this.findViewById(R.id.txt); 149. txt.setText("Activity 2" + "/n名字：" + name + "/n薪水：" + String.valueOf(salary)); 150. 151. Button btn = (Button) this.findViewById(R.id.btn); 152. btn.setText("返回前一個Activity"); 153. btn.setOnClickListener(new Button.OnClickListener() { 154. public void onClick(View v) { 155. // 返回參數給啓動者 156. MyActivity.this.setResult(Activity.RESULT_OK, intent); 157. MyActivity.this.finish(); 158. } 159. }); 160. } 161. } 162. 163. 164. AndroidManifest.xml 165. 166. 代碼 167. <?xml version="1.0" encoding="utf-8"?> 168. <manifest xmlns:android="http://schemas.android.com/apk/res/android" 169. package="com.webabcd.activity" android:versionCode="1" 170. android:versionName="1.0"> 171. <application android:icon="@drawable/icon" android:label="@string/app_name"> 172. <activity android:name=".Main" android:label="@string/app_name"> 173. <intent-filter> 174. <action android:name="android.intent.action.MAIN" /> 175. <category android:name="android.intent.category.LAUNCHER" /> 176. </intent-filter> 177. </activity> 178. <!-- 179. 如果有需要用到的 Activity ，則都要在這裏做相應的配置 180. --> 181. <activity android:name=".MyActivity" android:label="Activity 2" /> 182. </application> 183. <uses-sdk android:minSdkVersion="3" /> 184. </manifest> 185. 186. 187. 2、Service, Broadcast, BroadcastReceiver 的演示 188. Main.java 189. 190. 代碼 191. package com.webabcd.service; 192. 193. import android.app.Activity; 194. import android.content.BroadcastReceiver; 195. import android.content.ComponentName; 196. import android.content.Context; 197. import android.content.Intent; 198. import android.content.IntentFilter; 199. import android.content.ServiceConnection; 200. import android.os.Bundle; 201. import android.os.IBinder; 202. import android.view.View; 203. import android.view.View.OnClickListener; 204. import android.widget.TextView; 205. 206. /* 207. * startService() 和 bindService() 的區別 208. * startService() - 正常理解就好 209. * bindService() - 使當前上下文對象（本例中就是 Activity）通過一個 ServiceConnection 對象邦定到指定的 Service 。這樣，如果上下文對象銷燬了的話，那麼其對應的 Service 也會被銷燬 210. */ 211. public class Main extends Activity implements OnClickListener { 212. 213. private TextView txtMsg; 214. 215. @Override 216. public void onCreate(Bundle savedInstanceState) { 217. super.onCreate(savedInstanceState); 218. setContentView(R.layout.main); 219. 220. setTitle("android 之 service"); 221. 222. this.findViewById(R.id.btnStart).setOnClickListener(this); 223. this.findViewById(R.id.btnStop).setOnClickListener(this); 224. this.findViewById(R.id.btnBind).setOnClickListener(this); 225. this.findViewById(R.id.btnUnbind).setOnClickListener(this); 226. 227. txtMsg = (TextView)this.findViewById(R.id.txtMsg); 228. 229. // 實例化自定義的 BroadcastReceiver 230. receiver = new UpdateReceiver(); 231. IntentFilter filter = new IntentFilter(); 232. // 爲 BroadcastReceiver 指定 action ，使之用於接收同 action 的廣播 233. filter.addAction("com.webabcd.service.msg"); 234. 235. // 以編程方式註冊 BroadcastReceiver 。配置方式註冊 BroadcastReceiver 的例子見 AndroidManifest.xml 文件 236. // 一般在 OnStart 時註冊，在 OnStop 時取消註冊 237. this.registerReceiver(receiver, filter); 238. // this.unregisterReceiver(receiver); 239. 240. } 241. 242. @Override 243. public void onClick(View v) { 244. Intent intent = new Intent(Main.this, MyService.class); 245. switch (v.getId()) { 246. case R.id.btnStart: 247. this.startService(intent); 248. break; 249. case R.id.btnStop: 250. this.stopService(intent); 251. break; 252. case R.id.btnBind: 253. this.bindService(intent, conn, Context.BIND_AUTO_CREATE); 254. break; 255. case R.id.btnUnbind: 256. this.unbindService(conn); 257. break; 258. } 259. } 260. 261. // bindService() 所需的 ServiceConnection 對象 262. private ServiceConnection conn = new ServiceConnection() { 263. @Override 264. public void onServiceConnected(ComponentName className, IBinder service) { 265. 266. } 267. @Override 268. public void onServiceDisconnected(ComponentName className) { 269. 270. } 271. }; 272. 273. private String msg=""; 274. private UpdateReceiver receiver; 275. // 實現一個 BroadcastReceiver，用於接收指定的 Broadcast 276. public class UpdateReceiver extends BroadcastReceiver{ 277. 278. @Override 279. public void onReceive(Context context, Intent intent) { 280. msg = intent.getStringExtra("msg"); 281. 282. txtMsg.append(msg + "/n"); 283. } 284. 285. } 286. } 287. 288. MyService.java 289. 290. 代碼 291. package com.webabcd.service; 292. 293. import android.app.Service; 294. import android.content.Intent; 295. import android.os.IBinder; 296. import android.util.Log; 297. 298. // 演示 Service 的生命週期。具體信息運行程序後在 LogCat 中查看 299. public class MyService extends Service { 300. 301. @Override 302. public IBinder onBind(Intent intent) { 303. 304. Log.d("MyDebug", "onBind"); 305. sendMsg("onBind"); 306. 307. // TODO Auto-generated method stub 308. return null; 309. } 310. 311. @Override 312. public void onCreate() { 313. // TODO Auto-generated method stub 314. super.onCreate(); 315. 316. Log.d("MyDebug", "onCreate"); 317. sendMsg("onCreate"); 318. } 319. 320. @Override 321. public void onDestroy() { 322. // TODO Auto-generated method stub 323. super.onDestroy(); 324. 325. Log.d("MyDebug", "onDestroy"); 326. sendMsg("onDestroy"); 327. } 328. 329. @Override 330. public void onRebind(Intent intent) { 331. // TODO Auto-generated method stub 332. super.onRebind(intent); 333. 334. Log.d("MyDebug", "onRebind"); 335. sendMsg("onRebind"); 336. } 337. 338. @Override 339. public void onStart(Intent intent, int startId) { 340. super.onStart(intent, startId); 341. 342. Log.d("MyDebug", "onStart"); 343. sendMsg("onStart"); 344. } 345. 346. @Override 347. public boolean onUnbind(Intent intent) { 348. 349. Log.d("MyDebug", "onUnbind"); 350. sendMsg("onUnbind"); 351. 352. // TODO Auto-generated method stub 353. return super.onUnbind(intent); 354. } 355. 356. // 發送廣播信息 357. private void sendMsg(String msg){ 358. // 指定廣播目標的 action （注：指定了此 action 的 receiver 會接收此廣播） 359. Intent intent = new Intent("com.webabcd.service.msg"); 360. // 需要傳遞的參數 361. intent.putExtra("msg", msg); 362. // 發送廣播 363. this.sendBroadcast(intent); 364. } 365. } 366. 367. 368. MyBootReceiver.java 369. 370. 代碼 371. package com.webabcd.service; 372. 373. import android.content.BroadcastReceiver; 374. import android.content.Context; 375. import android.content.Intent; 376. import android.util.Log; 377. 378. public class MyBootReceiver extends BroadcastReceiver { 379. 380. // 用於接收滿足條件的 Broadcast（相應的 Broadcast 的註冊信息詳見 AndroidManifest.xml ，當系統啓動完畢後會調用這個廣播接收器） 381. @Override 382. public void onReceive(Context arg0, Intent arg1) { 383. Log.d("MyDebug", "onReceive"); 384. 385. // 啓動服務 386. Intent service = new Intent(arg0, MyService.class); 387. arg0.startService(service); 388. } 389. 390. } 391. 392. 393. AndroidManifest.xml 394. 395. 代碼 396. <?xml version="1.0" encoding="utf-8"?> 397. <manifest xmlns:android="http://schemas.android.com/apk/res/android" 398. package="com.webabcd.service" android:versionCode="1" 399. android:versionName="1.0"> 400. <application android:icon="@drawable/icon" android:label="@string/app_name"> 401. <activity android:name=".Main" android:label="@string/app_name"> 402. <intent-filter> 403. <action android:name="android.intent.action.MAIN" /> 404. <category android:name="android.intent.category.LAUNCHER" /> 405. </intent-filter> 406. </activity> 407. 408. <!-- 409. 如果有需要用到的 service ，則都要在這裏做相應的配置 410. --> 411. <service android:name=".MyService"></service> 412. 413. <!-- 414. 註冊一個 BroadcastReceiver 415. 其 intent-filter 爲 android.intent.action.BOOT_COMPLETED（用於接收系統啓動完畢的 Broadcast） 416. --> 417. <receiver android:name=".MyBootReceiver"> 418. <intent-filter> 419. <action android:name="android.intent.action.BOOT_COMPLETED" /> 420. </intent-filter> 421. </receiver> 422. </application> 423. 424. <!-- 425. 接受系統啓動完畢的 Broadcast 的權限 426. --> 427. <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" /> 428. <uses-sdk android:minSdkVersion="3" /> 429. </manifest> 430. 431. 432. OK