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;
 }
 };
}