前天有朋友問我說實現類似新聞輪播圖片的效果該怎麼實現？有什麼框架比較好一點。我想這不用什麼框架，自己寫一個就可以實現吧！好了，廢話不多說，先看一下實現的效果圖，再上程式碼。

實現的效果圖

activity_main.xml

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

    >
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    <android.support.v4.view.ViewPager
        android:layout_width="match_parent"
        android:id="@+id/viewPager"
        android:layout_height="match_parent"/>
        <LinearLayout
            android:layout_width="wrap_content"
 

            android:orientation="horizontal"
            android:layout_alignParentBottom="true"
            android:id="@+id/circleLayout"
            android:gravity="center"
            android:paddingBottom="30dp"
            android:layout_centerHorizontal="true"
            android:layout_height="wrap_content"
 
>
        </LinearLayout>
    </RelativeLayout>
</RelativeLayout>


ScrollPagerAdapter.java

public class ScrollPagerAdapter extends PagerAdapter {
    private Context context;
    private int[] mIamgeId;
    private ImageView[] mImageViews;

    public ScrollPagerAdapter(Context context, int[] mIamgeId) {
        this.mIamgeId = mIamgeId;
        this.context = context;
        mImageViews = new ImageView[mIamgeId.length];
        for (int i = 0; i < mIamgeId.length; i++) {//通過傳進來的圖片數量來確定給父佈局新增多少個子佈局ImageView來顯示圖片
            mImageViews[i] = new ImageView(context);
        }
    }

    @Override
    public int getCount() {
        return Integer.MAX_VALUE;//這個值需要設定為這個，如果只是設定為mIamgeId.length，那麼久無法實現迴圈滾動
    }

    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
        return arg0 == arg1;
    }

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

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        position = (position) % mIamgeId.length;
        ImageView iv = new ImageView(context);
        iv.setScaleType(ImageView.ScaleType.FIT_XY);
        iv.setImageResource(mIamgeId[position]);
        container.addView(iv);//裝載對應的ImageVIew
        return iv;

    }
}



MainActivity.java

public class MainActivity extends Activity {
    private ViewPager mViewPager;
    private LinearLayout mCircleLayout;//存放滾動時小圓點的父佈局
    private int[] mImageId = new int[]{R.mipmap.one, R.mipmap.two, R.mipmap.three, R.mipmap.four};//存放圖片id的陣列
    private ScrollPagerAdapter mScrollPagerAdapter;//ViewPager的介面卡
    private Context mContext;
    private int mPreviousEnabledPointPosition;//記錄上一張顯示圖片的位置
    private PersonalHandler mHandler; //訊息處理器

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = this;
        initView();//初始化view
        drawRadious();//給mCircleLayout佈局繪製對應的圓點，通過圖片的數量來繪製對應圓點的數目
        startRunImage();//開始輪播條滾動
    }

    //初始化View
    private void initView() {
        mViewPager = (ViewPager) findViewById(R.id.viewPager);
        mCircleLayout = (LinearLayout) findViewById(R.id.circleLayout);
        mScrollPagerAdapter = new ScrollPagerAdapter(mContext, mImageId);
        mViewPager.setAdapter(mScrollPagerAdapter);
    }

    //給mCircleLayout佈局繪製對應的圓點，通過圖片的數量來繪製對應圓點的數目
    private void drawRadious() {
        //進行小圓點的繪製
        mCircleLayout.removeAllViews();
        View v;
        LinearLayout.LayoutParams params;
        int size = mImageId.length;
        for (int i = 0; i < size; i++) {
            v = new View(mContext);
            v.setBackgroundResource(R.drawable.scroll_point_bg);
            params = new LinearLayout.LayoutParams(15, 15);
            if (i != 0) {
                params.leftMargin = 10;
            }
            v.setLayoutParams(params);
            v.setEnabled(false);
            mCircleLayout.addView(v);
        }
        mPreviousEnabledPointPosition = 0;
        mCircleLayout.getChildAt(mPreviousEnabledPointPosition).setEnabled(true);

        mViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                position = position % mImageId.length;
                mCircleLayout.getChildAt(mPreviousEnabledPointPosition).setEnabled(false);
                mCircleLayout.getChildAt(position).setEnabled(true);
                mPreviousEnabledPointPosition = position;
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    //開始輪播條滾動
    private void startRunImage() {
        if (mHandler == null) {
            mHandler = new PersonalHandler();
        } else {
            // 把佇列中的所有的訊息和任務全部清除出佇列
            mHandler.removeCallbacksAndMessages(null);
        }
        // 延時3秒鐘, 執行PersonalRunnable任務類中的run方法
        mHandler.postDelayed(new PersonalRunnable(), 3000);
    }

    //訊息處理器
    private class PersonalHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            // 當前是在主執行緒中, 把輪播圖切換到下一頁面
            int currentItem = (mViewPager.getCurrentItem() + 1) % mImageId.length;
            mViewPager.setCurrentItem(mViewPager.getCurrentItem() + 1);
            // 遞迴: postDelayed -> PersonalRunnable.run -> sendEmptyMessage -> handleMessage
            mHandler.postDelayed(new PersonalRunnable(), 3000);
        }
    }

    private class PersonalRunnable implements Runnable {
        @Override
        public void run() {
            mHandler.sendEmptyMessage(0);
        }
    }
}