Android基础：手势

一.物理按键
重写public boolean onKeyDown(int keyCode, KeyEvent event) 方法

import android.app.Activity;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.widget.Toast;

public class MainActivity extends Activity {
    private long exitTime = 0; //退出时间变量值
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            exit();
            return true;  //拦截返回键
        }
        return super.onKeyDown(keyCode, event);
    }
    public void exit() {
        if ((System.currentTimeMillis() - exitTime) > 2000) { //计算按键时间差是否大于两秒
            Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();
            exitTime = System.currentTimeMillis();
        } else {
            finish();
            System.exit(0); //销毁强制退出
        }
    }
}

二.长按事件
使用setOnLongClickListener(new View.OnLongClickListener() 方法

import android.app.Activity;
import android.media.Image;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ImageView imageView = (ImageView) findViewById(R.id.imageView); //获取图片组件
        imageView.setOnLongClickListener(new View.OnLongClickListener() { //创建长按监听事件
            @Override
            public boolean onLongClick(View v) {
                registerForContextMenu(v); //将长按事件注册菜单中
                openContextMenu(v); //打开菜单
                return false;
            }
        });
    }
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) { //创建菜单
        super.onCreateContextMenu(menu, v, menuInfo);
        menu.add("收藏"); //为菜单添加参数
        menu.add("举报");
    }
}

3.触摸事件
.setOnTouchListener(new View.OnTouchListener()

import android.app.Activity;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.RelativeLayout;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.relativeLayout); // 获取相对局管理器
        final HatView hat = new HatView(MainActivity.this); // 创建并实例化HatView类
        // 为帽子添加触摸事件监听
        hat.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                hat.bitmapX = event.getX()-80; // 设置帽子显示位置的X坐标
                hat.bitmapY = event.getY()-50; // 设置帽子显示位置的Y坐标
                hat.invalidate(); // 重绘hat组件
                return true;
            }
        });
        relativeLayout.addView(hat); //将hat添加到布局管理器中
    }
}

四.手势检测
1.让Mainactivity实现GestureDetector.OnGuestListener接口，并实现其所有方法
public class MainActivity extends AppCompatActivity implements GestureDetector.OnGestureListener{}
2.定义一个全局的手势检测器
GestureDetector detector;
3.将显示的图片加载到ViewFlipper中，并且初始化动画数组
ImageView imageView = new ImageView(this);
imageView.setImageResource(images[i]);
flipper.addView(imageView);
animation[0] = AnimationUtils.loadAnimation(this, R.anim.slide_in_left);
4.在需要的手势中设置动画
flipper.setInAnimation(animation[2]);

import android.gesture.Gesture;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.Toast;
import android.widget.ViewFlipper;

public class MainActivity extends AppCompatActivity implements GestureDetector.OnGestureListener {

    ViewFlipper flipper; //定义ViewFlipper
    GestureDetector detector; //定义手势检测器
    Animation[] animation = new Animation[4];//定义动画数组，为ViewFlipper指定切换动画
    final int distance = 50; //定义手势动作两点之间最小距离
    //定义图片数组
    private int[] images = new int[]{R.drawable.img01, R.drawable.img02, R.drawable.img03,
            R.drawable.img04, R.drawable.img05, R.drawable.img06, R.drawable.img07, R.drawable.img08,
            R.drawable.img09,
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        detector = new GestureDetector(this, this); //创建手势检测器
        flipper = (ViewFlipper) findViewById(R.id.flipper); //获取ViewFlipper
        for (int i = 0; i < images.length; i++) {
            ImageView imageView = new ImageView(this);
            imageView.setImageResource(images[i]);
            flipper.addView(imageView); //加载图片
        }
        //初始化动画数组
        animation[0] = AnimationUtils.loadAnimation(this, R.anim.slide_in_left);
        animation[1] = AnimationUtils.loadAnimation(this, R.anim.slide_out_left);
        animation[2] = AnimationUtils.loadAnimation(this, R.anim.slide_in_right);
        animation[3] = AnimationUtils.loadAnimation(this, R.anim.slide_out_right);
    }


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

    @Override
    public void onShowPress(MotionEvent e) {

    }

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

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

    @Override
    public void onLongPress(MotionEvent e) {

    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        /*
        如果第一个触点事件的X坐标到第二个触点事件的X坐标的距离超过distance就是从右向左滑动
         */
        if (e1.getX() - e2.getX() > distance) {
            //为flipper设置切换的动画效果
            flipper.setInAnimation(animation[2]);
            flipper.setOutAnimation(animation[1]);
            flipper.showPrevious();
            return true;
            /*
            如果第二个触点事件的X坐标到第一个触点事件的X坐标的距离超过distance就是从左向右滑动
             */
        } else if (e2.getX() - e1.getX() > distance) {
            //为flipper设置切换的动画
            flipper.setInAnimation(animation[0]);
            flipper.setOutAnimation(animation[3]);
            flipper.showNext();
            return true;
        }
        return false;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //将该Activity上的触碰事件交给GestureDetector处理
        return detector.onTouchEvent(event);
    }
}

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