Android 左右滑動小圓點(ViewPager)布局有兩種方法

第一種方法：
一、測驗如下，直接設定小圓點不是圖示

二、準備作業
1.在drawable創建dot.xml,設定小圓點，比較方便

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_selected="true">
        <shape android:shape="oval">
            <solid android:color="@color/black" />
            <corners android:radius="8dp" />
        </shape>
    </item>
    <item android:state_selected="false">
        <shape android:shape="oval">
            <solid android:color="@color/white" />
            <corners android:radius="8dp" />
        </shape>
    </item>
</selector>

2.布局小圓點的狀態可以被左右滑動dotview.xml

<!--?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:padding="5dp">

    <ImageView
        android:id="@+id/v_dot"
        android:layout_width="10dp"
        android:layout_height="10dp"
        android:src="@drawable/dot"/>
</LinearLayout>

3.分頁配接器自定義ViewPagerAdapter.java

public class ViewPagerAdapter extends PagerAdapter {
    private List<View> mViewList;

    public ViewPagerAdapter(List<View> mViewList) {
        this.mViewList = mViewList;
    }

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

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

    @Override
    public int getCount() {
        if (mViewList == null)
            return 0;
        return mViewList.size();
    }

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

三、使用作業：
1.activity_main.xml

<?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="wrap_content"
    android:background="#D4D3D3">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:background="#FFFFFF"
        android:orientation="vertical">

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

        <LinearLayout
            android:id="@+id/ll_dots"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:gravity="center"
            android:orientation="horizontal" />
    </RelativeLayout>
</LinearLayout>

分析下布局結構：
(1)首先是一個ViewPager,用于結合GridView實作左右滑動選單
(2)下面是一個LinearLayout，有多少個ViewPager的頁面就會inflate出多少個小圓點，并且在ViewPager翻頁時，也就是說在左右滑動時，下面小圓點的狀態也要相應地做出改變
2.MainActivity.java

public class MainActivity extends AppCompatActivity {
    private ViewPager mPager;
    private LinearLayout mLlDots;
    private LayoutInflater inflater;
    private List<View> mPagerList;
    private int pageCount = 3;//默認三個小點
    /**
     * 當前顯示的是第幾頁
     */
    private int curIndex = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mPager = (ViewPager) findViewById(R.id.viewpager);
        mLlDots = (LinearLayout) findViewById(R.id.ll_dots);
        inflater = LayoutInflater.from(this);
        mPagerList = new ArrayList<View>();
        //#FF9800：黃，#4CAF50：綠，#2196F3：藍
        String[] colors = {"#FF9800", "#4CAF50", "#2196F3"};
        for (int i = 0; i < pageCount; i++) {
            LinearLayout mLL = (LinearLayout) inflater.inflate(R.layout.linearlayout, mPager, false);
            mLL.setBackgroundColor(Color.parseColor(colors[i]));
            mPagerList.add(mLL);
        }
        //設定配接器
        mPager.setAdapter(new ViewPagerAdapter(mPagerList));
        //設定圓點
        setDotLayout();
    }

    /**
     * 設定圓點
     */
    public void setDotLayout() {
        for (int i = 0; i < pageCount; i++) {
            mLlDots.addView(inflater.inflate(R.layout.dotview, null));
        }
        // 默認顯示第一頁
        mLlDots.getChildAt(0).setSelected(true);
        mPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                // 取消原點選中
                mLlDots.getChildAt(curIndex).setSelected(false);
                // 原點選中
                mLlDots.getChildAt(position).setSelected(true);
                curIndex = position;
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }
}

這代碼中一句，布局LinearLayout隨著左右滑動小圓點翻頁

LinearLayout mLL = (LinearLayout) inflater.inflate(R.layout.linearlayout, mPager, false);

布局linearlayout.xml

<?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"/>

第二種方法：
1.測驗如下，小圓點圖示

2.dotview.xml

......
<ImageView
        android:id="@+id/v_dot"
        android:layout_width="10dp"
        android:layout_height="10dp"/>
......

3.設定二個小圓點圖示(黑白)，點擊鏈接：二個小圓點圖示.zip

        // 默認顯示第一頁
        mLlDots.getChildAt(0).findViewById(R.id.v_dot)
                .setBackgroundResource(R.drawable.dot_normal);

        mLlDots.getChildAt(1).findViewById(R.id.v_dot)
                .setBackgroundResource(R.drawable.dot_selected);

        mLlDots.getChildAt(2).findViewById(R.id.v_dot)
                .setBackgroundResource(R.drawable.dot_selected);

        mPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            public void onPageSelected(int position) {
                // 取消圓點選中
                mLlDots.getChildAt(curIndex)
                        .findViewById(R.id.v_dot)
                        .setBackgroundResource(R.drawable.dot_selected);
                // 圓點選中
                mLlDots.getChildAt(position)
                        .findViewById(R.id.v_dot)
                        .setBackgroundResource(R.drawable.dot_normal);
                curIndex = position;
            }

            public void onPageScrolled(int arg0, float arg1, int arg2) {
            }

            public void onPageScrollStateChanged(int arg0) {
            }
        });