技術Android開發之常用程式碼片段

1、設定視窗格式為半透明

getWindow().setFormat(PixelFormat.TRANSLUCENT);

2、Android中在非UI線程裡更新View的不同方法：

* Activity.runOnUiThread( Runnable )* View.post( Runnable )* View.postDelayed( Runnable, long )* Hanlder

3、全螢幕顯示視窗

requestWindowFeature(Window.FEATURE_NO_TITLE);getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

4、取得螢幕大小

方法A：WindowManager windowManager = getWindowManager();Display display = windowManager.getDefaultDisplay();hAndW[0] = display.getWidth();hAndW[1] = display.getHeight();方法B：DisplayMetrics dm = new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(dm);hAndW[0] = dm.widthPixels;hAndW[1] = dm.heightPixels;

5、調瀏覽器 載入網址

Uri uri = Uri.parse("http://www.google.com");Intent it = new Intent(Intent.ACTION_VIEW, uri);startActivity(it);

6、取得記憶體大小

ActivityManager.MemoryInfo outInfo = new ActivityManager.MemoryInfo();activityManager.getMemoryInfo(outInfo);//可用記憶體outInfo.availMem//是否在低記憶體狀態outInfo.lowMemory取得ScrollView的實際高度scrollview.getHeight()scrollview.getMeasuredHeight()scrollview.compute()scrollview.getLayoutParams().height

7、監聽App安裝/卸載事件

A.Define a class derived from class BroadcastReceiver;B.Register broadcast receiver;MyBroadcastReceiver myReceiver = new MyBroadcastReceiver();IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_INSTALL);filter.addAction(Intent.ACTION_PACKAGE_REMOVED);filter.addAction(Intent.ACTION_PACKAGE_ADDED);filter.addAction(Intent.ACTION_PACKAGE_CHANGED);filter.addAction(Intent.ACTION_PACKAGE_RESTARTED);...filter.addDataScheme("package"); //This line is very important. Otherwise, broadcast can't be received.registerReceiver(myReceiver, filter);Notes: The package name is Intent.mData. Intent.mData is not available in SDK 1.0, but it can be retrieved by calling Intent.getDataString();

8、取得IP地址

A.//Connect via WIFI 通過wifiWifiManager wifiManager = (WifiManager) getSystemService(WIFI_SERVICE);WifiInfo wifiInfo = wifiManager.getConnectionInfo();int ipAddress = wifiInfo.getIpAddress();B.//Connect via GPRS通過gprspublic String getLocalIpAddress(){try{for(Enumeration en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();){NetworkInterface intf = en.nextElement();for (Enumeration enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements();){InetAddress inetAddress = enumIpAddr.nextElement();if (!inetAddress.isLoopbackAddress()){return inetAddress.getHostAddress().toString();}}}}catch (SocketException ex){Log.e(S.TAG, ex.toString());}return null;}

9、ListView 後面adapter資料已更改，但是ListView沒有收到Notification首先，必須將 更新adapter資料的代碼放在：Handler.post(Runnable)方法中執行；然後，如果Adapter資料的來源如果是cursor（CursorAdapter）的話 可以cursor.requery一下，如果是別的可以強制調用一下notifyChange, notifyChange 會調用 invalidate 進行重繪； 10、類比HOME鍵

Intent i=new Intent(Intent.ACTION_MAIN);i.addCategory(Intent.CATEGORY_HOME);i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);context.startActivity(i);

11、設定焦點

editText.setFocusable(true);editText.requestFocus();editText.setFocusableInTouchMode(true);

 

12、MediaPalyer和SurfaceView播放視頻設定surfaceview

//設定SurfaceView自己不管理的緩衝區surfaceView.getHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//設定播放時開啟螢幕surfaceView.getHolder.setKeepScreenOn(true)

 

13、判斷SD卡是否存在

if(!Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED)){}