Android之无限轮播图源代码

Android轮播广告图是大家经常用到的一个控件今天便撸了一把代码

实现步骤

使用Viewpager进行实现图片滑动

设置ViewPager的数据，让其无限切换

Activity代码

public class PageBanner2Activity extends AppCompatActivity {

    private ViewPager mVp_content;
    private List<ImageView> mViewArrayList;
    private LinearLayout mLl_point;
    private int prePosition = 0;
    private boolean isRunning = true;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_page_banner2);
        initView();
    }

    private void initView() {
        mVp_content = (ViewPager) findViewById(R.id.vp_content);

        mLl_point = (LinearLayout) findViewById(R.id.ll_point);

        initData();

        startLunBO();
        mVp_content.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                switch (motionEvent.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        Log.e("PageBanner2Activity", "PageBanner2Activity onTouch()点击");
                        isRunning = false;
                        break;
                    case MotionEvent.ACTION_UP:
                        Log.e("PageBanner2Activity", "PageBanner2Activity onTouch()抬起");
                        isRunning = true;
                        break;

                    case MotionEvent.ACTION_MOVE:
                        isRunning = false;
                        Log.e("PageBanner2Activity", "PageBanner2Activity onTouch()抬起");

                        break;
                }

                return false;
            }
        });
    }

    private void startLunBO() {
        //开启轮播
        new Thread() {
            public void run() {
                while (isRunning) {

                    SystemClock.sleep(2000);

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            mVp_content.setCurrentItem(mVp_content.getCurrentItem() + 1);
                        }
                    });

                }
            }
        }.start();

    }

    private void initData() {
        mViewArrayList = new ArrayList<>();

        int[] imageIds = {R.mipmap.a, R.mipmap.b, R.mipmap.c, R.mipmap.d, R.mipmap.e};

        LinearLayout.LayoutParams layoutParams;
        View pointView;

        ImageView imageView;

        for (int i : imageIds) {
            imageView = new ImageView(this);
            imageView.setBackgroundResource(i);

            mViewArrayList.add(imageView);

            //创建小白点
            pointView = new View(this);
            pointView.setBackgroundResource(R.drawable.selector_point_bg);

            //添加到布局中
            layoutParams = new LinearLayout.LayoutParams(20, 20);

            if (i != 0) {
                layoutParams.leftMargin = 20;
            }

            //默认不选中
            pointView.setEnabled(false);
            mLl_point.addView(pointView, layoutParams);
        }

        //默认选中第一个
        mLl_point.getChildAt(0).setEnabled(true);

        //设置数据适配器
        MyPagerAdapter2 myPagerAdapter = new MyPagerAdapter2();
        mVp_content.setAdapter(myPagerAdapter);

        //添加监听
        mVp_content.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                int newPosition = position % mViewArrayList.size();

                mLl_point.getChildAt(prePosition).setEnabled(false);
                mLl_point.getChildAt(newPosition).setEnabled(true);
                prePosition = newPosition;
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

        int pos = Integer.MAX_VALUE / 2 - (Integer.MAX_VALUE / 2 % mViewArrayList.size());

        mVp_content.setCurrentItem(pos);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        isRunning = false;
    }
}   

ViewPager的数据适配器

class MyPagerAdapter2 extends PagerAdapter {

        @Override
        public int getCount() {
            //为了让其无限滑动，所以加大轮播图的数据
            return Integer.MAX_VALUE;
        }

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

        @Override
        public Object instantiateItem(ViewGroup container, int position) {

            int newPosition = position % mViewArrayList.size();

            ImageView imageView = mViewArrayList.get(newPosition);

            container.addView(imageView);

            return imageView;
        }

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

activity.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="200dp">

        <android.support.v4.view.ViewPager
            android:id="@+id/vp_content"
            android:layout_width="match_parent"
            android:layout_height="200dp"/>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:background="#878787"
            android:orientation="vertical">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:text="落花人独立微雨燕双飞"
                android:textColor="@android:color/white"
                android:textSize="20sp"/>

            <LinearLayout
                android:id="@+id/ll_point"
                android:layout_width="match_parent"
                android:layout_height="20dp"
                android:gravity="center"
                android:orientation="horizontal"></LinearLayout>
        </LinearLayout>
    </RelativeLayout>

</LinearLayout>

具体细节问题

如何设置ViewPager可以无限循环切换

我在代码中是这样设置的，首先设置ViewPager数据适配器中的返回数据个数为int的最大值，然后在instantiateItem方法中对position进行计算转换。随后在第一次加载ViewPager的时候，进行设置当前选中的条目为0--Integer.MAX_VALUE中间的一个值，从而就实现了左滑不会到头，右滑不会到头的展示状态

如何设置ViewPager自动的切换

设置ViewPager自动无限切换可以使用死循环的方式来进行解决。或者使用定时器，和定时任务来实现