20个Android很有用的代码片段

http://blog.chinaunix.net/u2/63867/showart_2346922.html 整理出15个Android很有用的代码片段 1：查看是否有存储卡插入 String status=Environment.getExternalStorageState(); if(status.equals(Enviroment.MEDIA_MOUNTED)) { 说明有SD卡插入 } 2：让某个Activity透明 OnCreate 中不设Layout this.setTheme(R.style.Theme_Transparent); 以下是 Theme_Transparent的定义（注意transparent_bg是一副透明的图片） 3：在屏幕元素中设置句柄 使用Activity.findViewById来取得屏幕上的元素的句柄. 使用该句柄您可以设置或获取任何该对象外露的值. TextView msgTextView = (TextView)findViewById(R.id.msg); msgTextView.setText(R.string.push_me); 4:发送短信 String body=”this is mms demo”; Intent mmsintent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts(”smsto”, number, null)); mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_BODY, body); mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_COMPOSE_MODE, true); mmsintent.putExtra(Messaging.KEY_ACTION_SENDTO_EXIT_ON_SENT, true); startActivity(mmsintent); 5:发送彩信 StringBuilder sb = new StringBuilder(); sb.append(”file://”); sb.append(fd.getAbsoluteFile()); Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts(”mmsto”, number, null)); // Below extra datas are all optional. intent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_SUBJECT, subject); intent.putExtra(Messaging.KEY_ACTION_SENDTO_MESSAGE_BODY, body); intent.putExtra(Messaging.KEY_ACTION_SENDTO_CONTENT_URI, sb.toString()); intent.putExtra(Messaging.KEY_ACTION_SENDTO_COMPOSE_MODE, composeMode); intent.putExtra(Messaging.KEY_ACTION_SENDTO_EXIT_ON_SENT, exitOnSent); startActivity(intent); 7：发送Mail mime = “img/jpg”; shareIntent.setDataAndType(Uri.fromFile(fd), mime); shareIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(fd)); shareIntent.putExtra(Intent.EXTRA_SUBJECT, subject); shareIntent.putExtra(Intent.EXTRA_TEXT, body); 8:注册一个 BroadcastReceiver registerReceiver(mMasterResetReciever, new IntentFilter(”oms.action.MASTERRESET”)); private BroadcastReceiver mMasterResetReciever = new BroadcastReceiver() { public void onReceive(Context context, Intent intent){ String action = intent.getAction(); if(”oms.action.MASTERRESET”.equals(action)){ RecoverDefaultConfig(); } } }; 9:定义ContentObserver，监听某个数据表 private ContentObserver mDownloadsObserver = new DownloadsChangeObserver(Downloads.CONTENT_URI); private class DownloadsChangeObserver extends ContentObserver { public DownloadsChangeObserver(Uri uri) { super(new Handler()); } @Override public void onChange(boolean selfChange) {｝ } 10:获得 手机UA public String getUserAgent() { String user_agent = ProductProperties.get(ProductProperties.USER_AGENT_KEY, null); return user_agent; } 11：清空手机上Cookie CookieSyncManager.createInstance(getApplicationContext()); CookieManager.getInstance().removeAllCookie(); 12：建立GPRS 连接 //Dial the GPRS link. private boolean openDataConnection() { // Set up data connection. DataConnection conn = DataConnection.getInstance(); if (connectMode == 0) { ret = conn.openConnection(mContext, “cmwap”, “cmwap”, “cmwap”); } else { ret = conn.openConnection(mContext, “cmnet”, “”, “”); } } 13：PreferenceActivity 用法 public class Setting extends PreferenceActivity ｛ public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); addPreferencesFromResource(R.xml.settings)； } ｝ Setting.xml: android:key=”seting2″ android:title=”@string/seting2″ android:summary=”@string/seting2″/> android:key=”seting1″ android:title=”@string/seting1″ android:summaryOff=”@string/seting1summaryOff” android:summaryOn=”@stringseting1summaryOff”/> 14:通过 HttpClient从指定server获取数据 DefaultHttpClient httpClient = new DefaultHttpClient(); HttpGet method = new HttpGet(“http://www.baidu.com/1.html”); HttpResponse resp; Reader reader = null; try { // AllClientPNames.TIMEOUT HttpParams params = new BasicHttpParams(); params.setIntParameter(AllClientPNames.CONNECTION_TIMEOUT, 10000); httpClient.setParams(params); resp = httpClient.execute(method); int status = resp.getStatusLine().getStatusCode(); if (status != HttpStatus.SC_OK) return false; // HttpStatus.SC_OK; return true; } catch (ClientProtocolException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { if (reader != null) try { reader.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } 15:显示toast Toast.makeText(this._getApplicationContext(), R.string._item, Toast.LENGTH_SHORT).show(); 16:在当前Activity中启动另外一个Activity startActivity(new Intent(this,目标Activity.class)); 17:从当前ContentView从查找控件 (Button)findViewById(R.id.btnAbout) R.id.btnAbout指控件id。 18:获取屏幕宽高 DisplayMetrics dm = new DisplayMetrics(); //获取窗口属性 getWindowManager().getDefaultDisplay().getMetrics(dm); int screenWidth = dm.widthPixels;//320 int screenHeight = dm.heightPixels;//480 19:无标题栏、全屏 //无标题栏 requestWindowFeature(Window.FEATURE_NO_TITLE); //全屏模式 getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); 注意在setContentView()之前调用，否则无效。 20注册activity 所有用到的Activity都必须在AndroidManifest.xml中注册，否则会报空指针错误。 如：，注意是包名+类名。