这是一个简单的Android代码，用于检测手势方向

在MainActivity.java和activity_main.xml中编写如下代码:

MainActivity.java

import java.util.ArrayList;

import android.app.Activity;
import android.gesture.Gesture;
import android.gesture.GestureLibraries;
import android.gesture.GestureLibrary;
import android.gesture.GestureOverlayView;
import android.gesture.GestureOverlayView.OnGesturePerformedListener;
import android.gesture.GestureStroke;
import android.gesture.Prediction;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends Activity implements
        OnGesturePerformedListener {

    GestureOverlayView gesture;
    GestureLibrary lib;
    ArrayList<Prediction> prediction;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        lib = GestureLibraries.fromRawResource(MainActivity.this,
                R.id.gestureOverlayView1);
        gesture = (GestureOverlayView) findViewById(R.id.gestureOverlayView1);
        gesture.addOnGesturePerformedListener(this);
    }

    @Override
    public void onGesturePerformed(GestureOverlayView overlay, Gesture gesture) {
        ArrayList<GestureStroke> strokeList = gesture.getStrokes();
        // prediction = lib.recognize(gesture);
        float f[] = strokeList.get(0).points;
        String str = "";

        if (f[0] < f[f.length - 2]) {
            str = "Right gesture";
        } else if (f[0] > f[f.length - 2]) {
            str = "Left gesture";
        } else {
            str = "no direction";
        }
        Toast.makeText(getApplicationContext(), str, Toast.LENGTH_LONG).show();

    }

}

activity_main.xml

<android.gesture.GestureOverlayView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android1="http://schemas.android.com/apk/res/android"
    xmlns:android2="http://schemas.android.com/apk/res/android"
    android:id="@+id/gestureOverlayView1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android1:orientation="vertical" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Draw gesture"
        android:textAppearance="?android:attr/textAppearanceMedium" />

</android.gesture.GestureOverlayView>

你不需要复杂的计算。 这可以通过使用来自GestureDetector类的OnGestureListener接口来完成。

在onFling方法中，你可以像这样检测所有四个方向:

MyGestureListener.java:

import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;

public class MyGestureListener implements GestureDetector.OnGestureListener{

    private static final long VELOCITY_THRESHOLD = 3000;

    @Override
    public boolean onDown(final MotionEvent e){ return false; }

    @Override
    public void onShowPress(final MotionEvent e){ }

    @Override
    public boolean onSingleTapUp(final MotionEvent e){ return false; }

    @Override
    public boolean onScroll(final MotionEvent e1, final MotionEvent e2, final float distanceX,
                        final float distanceY){ return false; }

    @Override
    public void onLongPress(final MotionEvent e){ }

    @Override
    public boolean onFling(final MotionEvent e1, final MotionEvent e2,
                       final float velocityX,
                       final float velocityY){

        if(Math.abs(velocityX) < VELOCITY_THRESHOLD 
                    && Math.abs(velocityY) < VELOCITY_THRESHOLD){
            return false;//if the fling is not fast enough then it's just like drag
        }

        //if velocity in X direction is higher than velocity in Y direction,
        //then the fling is horizontal, else->vertical
        if(Math.abs(velocityX) > Math.abs(velocityY)){
            if(velocityX >= 0){
                Log.i("TAG", "swipe right");
            }else{//if velocityX is negative, then it's towards left
                Log.i("TAG", "swipe left");
            }
        }else{
            if(velocityY >= 0){
                Log.i("TAG", "swipe down");
            }else{
                Log.i("TAG", "swipe up");
            }
        }

        return true;
    }
}

用法:

GestureDetector mDetector = new GestureDetector(MainActivity.this, new MyGestureListener());

view.setOnTouchListener(new View.OnTouchListener(){
    @Override
    public boolean onTouch(final View v, final MotionEvent event){
        return mDetector.onTouchEvent(event);
    }
});

@Mirek Rusin的回答很好。 但是，有一个小bug，需要修复

public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
            boolean result = false;
            try {
                float diffY = e2.getY() - e1.getY();
                float diffX = e2.getX() - e1.getX();
                if (Math.abs(diffX) > Math.abs(diffY)) {
                    if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
                        if (diffX > 0) {
                            if (getOnSwipeListener() != null) {
                                getOnSwipeListener().onSwipeRight();
                            }
                        } else {
                            if (getOnSwipeListener() != null) {
                                getOnSwipeListener().onSwipeLeft();
                            }
                        }
                        result = true;
                    }
                }
                else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
                    if (diffY > 0) {
                        if (getOnSwipeListener() != null) {
                            getOnSwipeListener().onSwipeBottom();
                        }
                    } else {
                        if (getOnSwipeListener() != null) {
                            getOnSwipeListener().onSwipeTop();
                        }
                    }
                    result = true;
                }

有什么不同?我们设置result = true，仅当我们检查了所有的需求(SWIPE_THRESHOLD和SWIPE_VELOCITY_THRESHOLD都是Ok的)。这是重要的，如果我们放弃滑动，如果一些需求没有实现，我们必须做smth在OnSwipeTouchListener的onTouchEvent方法!

如果你还需要处理点击事件，这里做一些修改:

public class OnSwipeTouchListener implements OnTouchListener {

    private final GestureDetector gestureDetector = new GestureDetector(new GestureListener());

    public boolean onTouch(final View v, final MotionEvent event) {
        return gestureDetector.onTouchEvent(event);
    }

    private final class GestureListener extends SimpleOnGestureListener {

        private static final int SWIPE_THRESHOLD = 100;
        private static final int SWIPE_VELOCITY_THRESHOLD = 100;


        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
            boolean result = false;
            try {
                float diffY = e2.getY() - e1.getY();
                float diffX = e2.getX() - e1.getX();
                if (Math.abs(diffX) > Math.abs(diffY)) {
                    if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
                        if (diffX > 0) {
                            result = onSwipeRight();
                        } else {
                            result = onSwipeLeft();
                        }
                    }
                } else {
                    if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
                        if (diffY > 0) {
                            result = onSwipeBottom();
                        } else {
                            result = onSwipeTop();
                        }
                    }
                }
            } catch (Exception exception) {
                exception.printStackTrace();
            }
            return result;
        }
    }

    public boolean onSwipeRight() {
        return false;
    }

    public boolean onSwipeLeft() {
        return false;
    }

    public boolean onSwipeTop() {
        return false;
    }

    public boolean onSwipeBottom() {
        return false;
    }
}

以及示例用法:

    background.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {
            toggleSomething();
        }
    });
    background.setOnTouchListener(new OnSwipeTouchListener() {
        public boolean onSwipeTop() {
            Toast.makeText(MainActivity.this, "top", Toast.LENGTH_SHORT).show();
            return true;
        }
        public boolean onSwipeRight() {
            Toast.makeText(MainActivity.this, "right", Toast.LENGTH_SHORT).show();
            return true;
        }
        public boolean onSwipeLeft() {
            Toast.makeText(MainActivity.this, "left", Toast.LENGTH_SHORT).show();
            return true;
        }
        public boolean onSwipeBottom() {
            Toast.makeText(MainActivity.this, "bottom", Toast.LENGTH_SHORT).show();
            return true;
        }
    });

对@Mirek Rusin的回答做了一点修改，现在你可以检测多点触摸了。这段代码在Kotlin上:

class OnSwipeTouchListener(ctx: Context, val onGesture: (gestureCode: Int) -> Unit) : OnTouchListener {

private val SWIPE_THRESHOLD = 200
private val SWIPE_VELOCITY_THRESHOLD = 200

private val gestureDetector: GestureDetector

var fingersCount = 0

fun resetFingers() {
    fingersCount = 0
}

init {
    gestureDetector = GestureDetector(ctx, GestureListener())
}

override fun onTouch(v: View, event: MotionEvent): Boolean {
    if (event.pointerCount > fingersCount) {
        fingersCount = event.pointerCount
    }
    return gestureDetector.onTouchEvent(event)
}

private inner class GestureListener : SimpleOnGestureListener() {

    override fun onDown(e: MotionEvent): Boolean {
        return true
    }

    override fun onFling(e1: MotionEvent, e2: MotionEvent, velocityX: Float, velocityY: Float): Boolean {
        var result = false
        try {
            val diffY = e2.y - e1.y
            val diffX = e2.x - e1.x
            if (Math.abs(diffX) > Math.abs(diffY)) {
                if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
                    if (diffX > 0) {
                        val gesture = when (fingersCount) {
                            1 -> Gesture.SWIPE_RIGHT
                            2 -> Gesture.TWO_FINGER_SWIPE_RIGHT
                            3 -> Gesture.THREE_FINGER_SWIPE_RIGHT
                            else -> -1
                        }
                        if (gesture > 0) {
                            onGesture.invoke(gesture)
                        }
                    } else {
                        val gesture = when (fingersCount) {
                            1 -> Gesture.SWIPE_LEFT
                            2 -> Gesture.TWO_FINGER_SWIPE_LEFT
                            3 -> Gesture.THREE_FINGER_SWIPE_LEFT
                            else -> -1
                        }
                        if (gesture > 0) {
                            onGesture.invoke(gesture)
                        }
                    }
                    resetFingers()
                }
            } else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
                if (diffY > 0) {
                    val gesture = when (fingersCount) {
                        1 ->  Gesture.SWIPE_DOWN
                        2 -> Gesture.TWO_FINGER_SWIPE_DOWN
                        3 -> Gesture.THREE_FINGER_SWIPE_DOWN
                        else -> -1
                    }
                    if (gesture > 0) {
                        onGesture.invoke(gesture)
                    }
                } else {
                    val gesture = when (fingersCount) {
                        1 ->  Gesture.SWIPE_UP
                        2 -> Gesture.TWO_FINGER_SWIPE_UP
                        3 -> Gesture.THREE_FINGER_SWIPE_UP
                        else -> -1
                    }
                    if (gesture > 0) {
                        onGesture.invoke(gesture)
                    }
                }
                resetFingers()
            }
            result = true

        } catch (exception: Exception) {
            exception.printStackTrace()
        }

        return result
    }
}}

在姿态。SWIPE_RIGHT和其他是唯一的整数标识符的手势，我用它来检测一种手势在我的活动:

rootView?.setOnTouchListener(OnSwipeTouchListener(this, {
    gesture -> log(Gesture.parseName(this, gesture))
}))

这里的gesture是一个整型变量它包含了我之前传递的值。

@Mirek Rusin的Kotlin版本在这里:

OnSwipeTouchListener。kt:

open class OnSwipeTouchListener(ctx: Context) : OnTouchListener {

    private val gestureDetector: GestureDetector

    companion object {

        private val SWIPE_THRESHOLD = 100
        private val SWIPE_VELOCITY_THRESHOLD = 100
    }

    init {
        gestureDetector = GestureDetector(ctx, GestureListener())
    }

    override fun onTouch(v: View, event: MotionEvent): Boolean {
        return gestureDetector.onTouchEvent(event)
    }

    private inner class GestureListener : SimpleOnGestureListener() {


        override fun onDown(e: MotionEvent): Boolean {
            return true
        }

        override fun onFling(e1: MotionEvent, e2: MotionEvent, velocityX: Float, velocityY: Float): Boolean {
            var result = false
            try {
                val diffY = e2.y - e1.y
                val diffX = e2.x - e1.x
                if (Math.abs(diffX) > Math.abs(diffY)) {
                    if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
                        if (diffX > 0) {
                            onSwipeRight()
                        } else {
                            onSwipeLeft()
                        }
                        result = true
                    }
                } else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
                    if (diffY > 0) {
                        onSwipeBottom()
                    } else {
                        onSwipeTop()
                    }
                    result = true
                }
            } catch (exception: Exception) {
                exception.printStackTrace()
            }

            return result
        }


    }

    open fun onSwipeRight() {}

    open fun onSwipeLeft() {}

    open fun onSwipeTop() {}

    open fun onSwipeBottom() {}
}

用法:

view.setOnTouchListener(object : OnSwipeTouchListener(context) {

    override fun onSwipeTop() {
        super.onSwipeTop()
    }

    override fun onSwipeBottom() {
        super.onSwipeBottom()
    }

    override fun onSwipeLeft() {
        super.onSwipeLeft()
    }

    override fun onSwipeRight() {
        super.onSwipeRight()
    }
})

open关键字对我来说很重要……