ViewPager+Handler实现轮播加手势滑动

最新推荐文章于 2020-09-06 11:12:10 发布

原创最新推荐文章于 2020-09-06 11:12:10 发布 · 310 阅读

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CC 4.0 BY-SA版权

文章标签：

#viewpager

本文介绍了一个简单的Android应用中实现轮播图效果的方法。通过ViewPager和自定义适配器完成图片轮播，并利用Handler实现自动轮播及触摸暂停功能。

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package com.example.peng.fuxiqi;

import android.os.Handler;
import android.os.Message;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements Handler.Callback, View.OnTouchListener {

    private ViewPager mViewPager;
    private List<ImageView> list;
    private MyAdapter  adapter;
    private int[] imgarray=new int[]{R.mipmap.txt_theme29,R.mipmap.txt_theme17,R.mipmap.txt_theme26,R.mipmap.txt_theme29,R.mipmap.txt_theme17};
    private Handler handler;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mViewPager = (ViewPager) findViewById(R.id.viewpager_main);
        initData();
        adapter=new MyAdapter();
        mViewPager.setAdapter(adapter);
        handler=new Handler(this);
        initTime();
        setListener();
        mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                if (list.size()>1){
                    if (position<1){
                        position=list.size()-2;
                        mViewPager.setCurrentItem(position,false);
                    }else if (position>(list.size()-2)){
                        mViewPager.setCurrentItem(1,false);
                        position=1;
                    }
                }

            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    private void setListener() {
        mViewPager.setOnTouchListener(this);
    }

    private void initTime() {
      handler.sendEmptyMessage(0);
    }

    private void initData() {
        list=new ArrayList<>();
        for (int i = 0; i <imgarray.length ; i++) {
            ImageView img=new ImageView(MainActivity.this);
            img.setImageResource(imgarray[i]);
            list.add(img);
        }
    }

    @Override
    public boolean handleMessage(Message msg) {
        mViewPager.setCurrentItem(mViewPager.getCurrentItem()+1);
        handler.sendEmptyMessageDelayed(0,3000);
        return false;
    }
//触摸时handler移除发送消息，抬起时发送消息
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        handler.removeMessages(0);
        if (event.getAction()==MotionEvent.ACTION_UP){
            handler.sendEmptyMessageDelayed(0,3000);
        }
        return false;
    }
//适配器
    public class MyAdapter extends PagerAdapter{
        @Override
        public int getCount() {
            return list.size();
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view==object;
        }

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            container.addView(list.get(position));
            return list.get(position);
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView(list.get(position));
        }
    }
}