Android开发之常用代码片段
1、设置窗口格式为半透明
getWindow().setFormat(PixelFormat.TRANSLUCENT);
2、Android中在非UI线程里更新View的不同方法：
* Activity.runOnUiThread( Runnable )
* View.post( Runnable )
* View.postDelayed( Runnable, long )
* Hanlder
3、全屏显示窗口
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
4、取得屏幕大小
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、调浏览器 载入网址
Uri uri = Uri.parse("http://www.google.com");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
6、取得内存大小
ActivityManager.MemoryInfo outInfo = new ActivityManager.MemoryInfo();
activityManager.getMemoryInfo(outInfo);
//可用内存
outInfo.availMem
//是否在低内存状态
outInfo.lowMemory
取得ScrollView的实际高度
scrollview.getHeight()
scrollview.getMeasuredHeight()
scrollview.compute()
scrollview.getLayoutParams().height
7、监听App安装/卸载事件
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 通过wifi
WifiManager wifiManager = (WifiManager) getSystemService(WIFI_SERVICE);
WifiInfo wifiInfo = wifiManager.getConnectionInfo();
int ipAddress = wifiInfo.getIpAddress();
B.
//Connect via GPRS通过gprs
public String getLocalIpAddress(){
try{
for(Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();){
NetworkInterface intf = en.nextElement();
for (Enumeration<InetAddress> 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 后面adapter数据已更改，但是ListView没有收到Notification
首先，必须将 更新adapter数据的代码放在：Handler.post(Runnable)方法中执行；
然后，如果Adapter数据的来源如果是cursor（CursorAdapter）的话 可以cursor.requery一下，如果是别的可以强制调用一下notifyChange, notifyChange 会调用 invalidate 进行重绘；
10、模拟HOME键
Intent i=new Intent(Intent.ACTION_MAIN);
i.addCategory(Intent.CATEGORY_HOME);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(i);
11、设置焦点
editText.setFocusable(true);
editText.requestFocus();
editText.setFocusableInTouchMode(true);
