public class GestureActivity extends Activity {  private GestureDetector gestureDetector;  private Screen screen;  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);    gestureDetector = new GestureDetector(this,onGestureListener);    //得到屏幕的大小    screen = GestureUtils.getScreenPix(this);  }  @Override  public boolean onTouchEvent(MotionEvent event) {    return gestureDetector.onTouchEvent(event);  }  GestureDetector.OnGestureListener onGestureListener = new GestureDetector.SimpleOnGestureListener(){    @Override    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,        float velocityY) {      float x = e2.getX() - e1.getX();      float y = e2.getY() - e1.getY();      //限制必須得劃過屏幕的1/3才能算劃過      float x_limit = screen.widthPixels / 3;      float y_limit = screen.heightPixels / 3;      float x_abs = Math.abs(x);      float y_abs = Math.abs(y);      if(x_abs >= y_abs){        //gesture left or right        if(x > x_limit || x < -x_limit){          if(x>0){            //right            show("right");          }else if(x            //left            show("left");          }        }      }else{        //gesture down or up        if(y > y_limit || y < -y_limit){          if(y>0){            //down            show("down");          }else if(y            //up            show("up");          }        }      }      return true;    }  };  private void show(String value){    Toast.makeText(this, value, Toast.LENGTH_SHORT).show();  }}

public class GestureUtils {  //獲取屏幕的大小  public static Screen getScreenPix(Context context) {    DisplayMetrics dm = new DisplayMetrics();    WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);    windowManager.getDefaultDisplay().getMetrics(dm);    return new Screen(dm.widthPixels,dm.heightPixels);  }  public static class Screen{    public int widthPixels;    public int heightPixels;    public Screen(){    }    public Screen(int widthPixels,int heightPixels){      this.widthPixels=widthPixels;      this.heightPixels=heightPixels;    }    @Override    public String toString() {      return "("+widthPixels+","+heightPixels+")";    }  }}