Java Reflection 機制, 以 DisplayManager 為例

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DisplayManager 有很多隱藏方法, 如scanWifiDisplays, connectWifiDisplay, disconnectWifiDisplay. 我們今天就來試試如何調用.

    private Handler mWfdHandler = new Handler();

    //suport scan, connect
   public class WfdMethod implements Runnable {
        // Time between wifi display scans when actively scanning in milliseconds.
        //private static final int WIFI_DISPLAY_SCAN_INTERVAL = 15000;
        Method mMethod = null;
        String mArg = null;
        boolean bResult = false;
        public WfdMethod( String szMethod, String szArg) {
           try{
               if(szMethod == "scan"){
                   mMethod = DisplayManager.class.getMethod("scanWifiDisplays");
                   mArg = null;
               }
               else if(szMethod == "connect")
               {
                    mMethod = DisplayManager.class.getMethod("connectWifiDisplay",new Class[]{String.class} );
                   mArg = szArg;

               }
                  else if(szMethod == "disconnect")
               {
                    mMethod = DisplayManager.class.getMethod("disconnectWifiDisplay" );
                   mArg = null;

               }
           }
           catch(NoSuchMethodException e){
               Log.d(TAG, e.toString());

           }

        }


       @Override
       public void run() {
           DisplayManager displayManager = (DisplayManager)m_parent.getSystemService(Context.DISPLAY_SERVICE);

           try{
               Log.d(TAG, "running "+ mMethod.toString());
               if(mArg == null)
                   mMethod.invoke(displayManager );
               else
                   mMethod.invoke(displayManager,new Object[] {mArg} );
           }
           catch(IllegalAccessException e)
           {
               Log.d(TAG, e.toString());

           }
           catch(InvocationTargetException e){
               Log.d(TAG, e.toString());

           }
           catch( IllegalArgumentException e)
           {
               Log.d(TAG, e.toString());

           }
           bResult = true;
       }

   }

2. 調用

mWfdHandler.postDelayed(new WfdMethod("scan", null), 0);

mWfdHandler.postDelayed(new WfdMethod("connect", deviceAddress), 0);

mWfdHandler.postDelayed(new WfdMethod("disconnect", null), 0);

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