GestureDetector- 滑屏手势方式实现

今天做的项目中，需要使用滑屏来调出一个界面，经过自己的尝试，结合网上的方法，成功实现了。

代码如下

package com.example.text;

import android.app.Activity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.widget.TextView;

public class MainActivity extends Activity implements OnGestureListener {
     private GestureDetector mGestureDetector;
     private TextView tv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv=(TextView) findViewById(R.id.tv);
//这个如果直接写一个this，会提示过时。另外，如果两个参数都写成this，会报错。原因不知
        mGestureDetector = new GestureDetector(MainActivity.this, this);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // TODO Auto-generated method stub

     //通过event自动判断手势，回调相应的方法
    return mGestureDetector.onTouchEvent(event);

    }
//按下屏幕触发，打印的是坐标 
 @Override
    public boolean onDown(MotionEvent arg0) {
        // TODO Auto-generated method stub
        tv.setText(arg0.getX()+"    "+arg0.getY());
        return false;
    }
//滑动屏幕的时候触发，打印的分别是起点跟终点的坐标 
 @Override
    public boolean onFling(MotionEvent arg0, MotionEvent arg1, float arg2,
            float arg3) {
        // TODO Auto-generated method stub
        tv.setText("arg1.getX()="+arg1.getX()+"   arg0.getX()="+arg1.getY()+"     arg2="+arg2+"   arg3="+arg3);
        return true;
    }

    @Override
    public void onLongPress(MotionEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public boolean onScroll(MotionEvent arg0, MotionEvent arg1, float arg2,
            float arg3) {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public void onShowPress(MotionEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public boolean onSingleTapUp(MotionEvent arg0) {
        // TODO Auto-generated method stub
        return false;
    }
}

这个类的使用步骤如下

1.定义手势类：private GestureDetector mGestureDetector;

2.初始化类：这个是跟其他控件设置监听一样的，有多种方法

　　1）匿名内部类：

mGestureDetector = new GestureDetector(MainActivity.this, new OnGestureListener() {

            @Override
            public boolean onSingleTapUp(MotionEvent arg0) {
                // TODO Auto-generated method stub
                return false;
            }

            @Override
            public void onShowPress(MotionEvent arg0) {
                // TODO Auto-generated method stub

            }

            @Override
            public boolean onScroll(MotionEvent arg0, MotionEvent arg1, float arg2,
                    float arg3) {
                // TODO Auto-generated method stub
                return false;
            }

            @Override
            public void onLongPress(MotionEvent arg0) {
                // TODO Auto-generated method stub

            }

            @Override
            public boolean onFling(MotionEvent arg0, MotionEvent arg1, float arg2,
                    float arg3) {
                // TODO Auto-generated method stub
                return false;
            }

            @Override
            public boolean onDown(MotionEvent arg0) {
                // TODO Auto-generated method stub
                return false;
            }
        });

　　2).直接让主类继承：

public class MainActivity extends Activity implements OnGestureListener{

}

　　3).内部类

 class MyOnGestureListener  implements OnGestureListener{

}

3.在onTouchEvent()事件中使用这个类

   @Override
    public boolean onTouchEvent(MotionEvent event) {
        // TODO Auto-generated method stub

     //通过event自动判断手势，回调相应的方法
    return mGestureDetector.onTouchEvent(event);

    }

不过，现在还有一点不是很明白，就是方法中的return false跟return true有什么区别