Android学习笔记之不同activity之间滑动切换

      之前学习到ViewFlipper实现一个Activity多个控件之间的滑动切换，现在来学习多个activity之间的滑动切换。

        1.继承OnTouchListner和OnGestureListener.

public class WeatherActivity extends Activity implements OnTouchListener,OnGestureListener{      

//  2.创建GesTureDetector对象（创建时必须实现OnGestureListnener监听器实

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

// 3.为当前Acitivity的布局页面添加setOnTouchListener事件。（OnCreate函数）    

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

//注意：若不加setLongClickable(true)的话OnFling会失效，如果不写这句的话OnGestureListener的重写方法OnDown方法返回true也可以。只有这样，view才///能够处理不同于Tap（轻触）的hold（即ACTION_MOVE，或者多个ACTION_DOWN），我们同样可以通过layout定义中的android:longClickable来做到这一点。   //4.将Acityvity的TouchEvent事件交给GestureDetector处理@Override
	public boolean onTouch(View v, MotionEvent event) {
		// TODO Auto-generated method stub
		return gd.onTouchEvent(event);
	}    

//  5.重载onFling函数	

@Override
//e1  The first down motion event that started the fling.手势起点的移动事件  
//e2  The move motion event that triggered the current onFling.当前手势点的移动事件  
//velocityX   The velocity of this fling measured in pixels per second along the x axis.每秒x轴方向移动的像素  
//velocityY   The velocity of this fling measured in pixels per second along the y axis.每秒y轴方向移动的像素  

	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, "向左手势", Toast.LENGTH_SHORT).show(); 

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