如何在 Android 中检测左右滑动方向和上下滑动方向?
androidapps/applicationsmobile development
本示例演示了如何在 Android 中检测左右滑动方向和上下滑动方向。
步骤 1 − 在 Android Studio 中创建一个新项目，前往"文件"->"新建项目"，并填写所有必填信息以创建新项目。
步骤 2 − 将以下代码添加到 res/layout/activity_main.xml。
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/relativeLayout" android:layout_width="match_parent" android:layout_height="match_parent" android:padding="16dp" tools:context=".MainActivity"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" android:text="Swipe to Detect swipe Event" android:textSize="24sp" android:textStyle="bold" /> </RelativeLayout>
步骤 3 − 将以下代码添加到 src/MainActivity.java
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
OnSwipeTouchListener onSwipeTouchListener;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
onSwipeTouchListener = new OnSwipeTouchListener(this, findViewById(R.id.relativeLayout));
}
public static class OnSwipeTouchListener implements View.OnTouchListener {
private final GestureDetector gestureDetector;
Context context;
OnSwipeTouchListener(Context ctx, View mainView) {
gestureDetector = new GestureDetector(ctx, new GestureListener());
mainView.setOnTouchListener(this);
context = ctx;
}
@Override
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
public class GestureListener extends
GestureDetector.SimpleOnGestureListener {
private static final int SWIPE_THRESHOLD = 100;
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
@Override
public boolean onDown(MotionEvent e) {
return true;
}
@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) {
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;
}
}
void onSwipeRight() {
Toast.makeText(context, "Swiped Right", Toast.LENGTH_SHORT).show();
this.onSwipe.swipeRight();
}
void onSwipeLeft() {
Toast.makeText(context, "Swiped Left", Toast.LENGTH_SHORT).show();
this.onSwipe.swipeLeft();
}
void onSwipeTop() {
Toast.makeText(context, "Swiped Up", Toast.LENGTH_SHORT).show();
this.onSwipe.swipeTop();
}
void onSwipeBottom() {
Toast.makeText(context, "Swiped Down", Toast.LENGTH_SHORT).show();
this.onSwipe.swipeBottom();
}
interface onSwipeListener {
void swipeRight();
void swipeTop();
void swipeBottom();
void swipeLeft();
}
onSwipeListener onSwipe;
}
}
步骤 4 − 将以下代码添加到 androidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
让我们尝试运行您的应用程序。假设您已将实际的 Android 移动设备连接到电脑。要从 Android Studio 运行该应用程序，请打开项目的某个 Activity 文件，然后点击工具栏上的"运行"
图标。选择您的移动设备作为选项，然后检查您的移动设备是否显示您的默认屏幕 −
点击此处下载项目代码。
