Android实现滑动屏幕切换图片

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  tools:context="com.example.administrator.hand_gliding.MainActivity">
 
  <ImageView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/imageView"
    android:src="@drawable/a1"/>
 
</LinearLayout>

package com.example.administrator.hand_gliding;
 
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.ImageView;
 
public class MainActivity extends AppCompatActivity {
 
  //定义图片
  private int[] resId = new int[]{
      R.drawable.a1,R.drawable.a2,R.drawable.a3,R.drawable.a4,
      R.drawable.a5,R.drawable.a6,R.drawable.a7
  };
  //图片下标序号
  private int count = 0;
  //定义手势监听对象
  private GestureDetector gestureDetector;
  //定义ImageView对象
  private ImageView iv;
 
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    
    iv = (ImageView)findViewById(R.id.imageView);        //获取ImageView控件id
    gestureDetector = new GestureDetector(onGestureListener);  //设置手势监听由onGestureListener处理
 
  }
 
  //当Activity被触摸时回调
  public boolean onTouchEvent(MotionEvent event){
    return gestureDetector.onTouchEvent(event);
  }
  //自定义GestureDetector的手势识别监听器
  private GestureDetector.OnGestureListener onGestureListener
      = new GestureDetector.SimpleOnGestureListener(){
    //当识别的手势是滑动手势时回调onFinger方法
    public boolean onFling(MotionEvent e1,MotionEvent e2,float velocityX,float velocityY){
      //得到手触碰位置的起始点和结束点坐标 x , y ，并进行计算
      float x = e2.getX()-e1.getX();
      float y = e2.getY()-e1.getY();
      //通过计算判断是向左还是向右滑动
      if(x > 0){
        count++;
        count%=(resId.length-1);    //想显示多少图片，就把定义图片的数组长度-1
      }else if(x < 0){
        count--;
        count=(count+(resId.length-1))%(resId.length-1);
      }
 
      iv.setImageResource(resId[count]); //切换imageView的图片
      return true;
    }
  };
}