Android學習筆記之不同activity之間滑動切換

      之前學習到ViewFlipper實現一個Activity多個控件之間的滑動切換，現在來學習多個activity之間的滑動切換。

        1.繼承OnTouchListner和OnGestureListener.

public class WeatherActivity extends Activity implements OnTouchListener,OnGestureListener{      

//  2.創建GesTureDetector對象（創建時必須實現OnGestureListnener監聽器實

//例） GestureDetector gd;
 @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        gd = new GestureDetector((OnGestureListener)this);    

// 3.爲當前Acitivity的佈局頁面添加setOnTouchListener事件。（OnCreate函數）    

        LinearLayout ll = (LinearLayout) findViewById(R.id.weather_layout);
        ll.setOnTouchListener(this);
        ll.setLongClickable(true);

//注意：若不加setLongClickable(true)的話OnFling會失效，如果不寫這句的話OnGestureListener的重寫方法OnDown方法返回true也可以。只有這樣，view才///能夠處理不同於Tap（輕觸）的hold（即ACTION_MOVE，或者多個ACTION_DOWN），我們同樣可以通過layout定義中的android:longClickable來做到這一點。   //4.將Acityvity的TouchEvent事件交給GestureDetector處理@Override
	public boolean onTouch(View v, MotionEvent event) {
		// TODO Auto-generated method stub
		return gd.onTouchEvent(event);
	}    

//  5.重載onFling函數	

@Override
//e1  The first down motion event that started the fling.手勢起點的移動事件  
//e2  The move motion event that triggered the current onFling.當前手勢點的移動事件  
//velocityX   The velocity of this fling measured in pixels per second along the x axis.每秒x軸方向移動的像素  
//velocityY   The velocity of this fling measured in pixels per second along the y axis.每秒y軸方向移動的像素  

	public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
			float velocityY) {
		// TODO Auto-generated method stub
		if(e1.getX() - e2.getX() > FLING_MIN_DISTANCE&&Math.abs(velocityX) > FLING_MIN_VELOCITY)
		{
			Intent intent = new Intent(WeatherActivity.this,CityActivity.class);
			startActivity(intent);
			 Toast.makeText(this, "向左手勢", Toast.LENGTH_SHORT).show(); 

		}
		else if (e2.getX()-e1.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) >FLING_MIN_VELOCITY) {
			
			//切換Activity
			Intent intent = new Intent(WeatherActivity.this, IndexActivity.class);
			startActivity(intent);
			Toast.makeText(this, "向右手勢", Toast.LENGTH_SHORT).show();
		}
		
		return false;
	}