MyDialog extends Dialog 

//Dialog的构造函数中写 
  this.setOnDismissListener(new OnDismissListener() { 
   @Override 
   public void onDismiss(DialogInterface dialog) { 
    hideKeyBoard(); 
   } 
  }); 
//edContent是输入框 
 public void hideKeyBoard(){ 
  InputMethodManager inputMethodManager = (InputMethodManager) getContext().getSystemService(Context.INPUT_METHOD_SERVICE); 
  inputMethodManager.hideSoftInputFromWindow(edContent.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS); 
 } 

public boolean hideSoftInputFromWindow(IBinder windowToken, int flags, 
    ResultReceiver resultReceiver) { 
  checkFocus(); 
  synchronized (mH) { 
    if (mServedView == null || mServedView.getWindowToken() != windowToken) { 
      return false; 
    } 
 
    try { 
      return mService.hideSoftInput(mClient, flags, resultReceiver); 
    } catch (RemoteException e) { 
    } 
    return false; 
  } 
} 

this.setCanceledOnTouchOutside(true); 

public boolean onTouchEvent(MotionEvent event) { 
  if (mCancelable && mShowing && mWindow.shouldCloseOnTouch(mContext, event)) { 
    cancel(); 
    return true; 
  } 
   
  return false; 
} 

public void cancel() { 
  if (!mCanceled && mCancelMessage != null) { 
    mCanceled = true; 
    // Obtain a new message so this dialog can be re-used 
    Message.obtain(mCancelMessage).sendToTarget(); 
  } 
  dismiss(); 
} 

public boolean shouldCloseOnTouch(Context context, MotionEvent event) { 
  if (mCloseOnTouchOutside && event.getAction() == MotionEvent.ACTION_DOWN 
      && isOutOfBounds(context, event) && peekDecorView() != null) { 
    return true; 
  } 
  return false; 
} 
 
private boolean isOutOfBounds(Context context, MotionEvent event) { 
  final int x = (int) event.getX(); 
  final int y = (int) event.getY(); 
  final int slop = ViewConfiguration.get(context).getScaledWindowTouchSlop(); 
  final View decorView = getDecorView(); 
  return (x < -slop) || (y < -slop) 
      || (x > (decorView.getWidth()+slop)) 
      || (y > (decorView.getHeight()+slop)); 
} 

@Override 
public boolean onTouchEvent(MotionEvent event) { 
 if (isShowing() && shouldCloseOnTouch(getContext(),event)){ 
  hideKeyBoard(); 
 } 
 return super.onTouchEvent(event); 
} 
public boolean shouldCloseOnTouch(Context context, MotionEvent event) { 
 if (event.getAction() == MotionEvent.ACTION_DOWN 
     && isOutOfBounds(context, event) && getWindow().peekDecorView() != null) { 
  return true; 
 } 
 return false; 
} 
private boolean isOutOfBounds(Context context, MotionEvent event) { 
 final int x = (int) event.getX(); 
 final int y = (int) event.getY(); 
 final int slop = ViewConfiguration.get(context).getScaledWindowTouchSlop(); 
 final View decorView = getWindow().getDecorView(); 
 return (x < -slop) || (y < -slop) 
     || (x > (decorView.getWidth()+slop)) 
     || (y > (decorView.getHeight()+slop)); 
}