Android中ViewPager和PagerAdapter的簡單使用

需求

使用ViewPager和PagerAdapter簡單的做一個當前界面橫向滑動可以切換圖片的功能。

佈局

activity.xml佈局文件只要加入ViewPager和TextView控件即可

<?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">

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

    <TextView
        android:id="@+id/image_index_of_total"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:padding="20dp"
        android:text="0/0"
        android:textColor="@color/white"
        android:textSize="24sp" />

</RelativeLayout>

代碼

代碼的一些初始化

	private ViewPager viewPager;
    private PagerAdapter pagerAdapter;
    private int[] resArray;
    private TextView indexOfTotalTV;

	private void initDatas()
    {
        resArray =
                new int[]{R.drawable.e1, R.drawable.e2, R.drawable.e3, R.drawable.e4, R.drawable.e5,
                        R.drawable.e6, R.drawable.e7, R.drawable.e8, R.drawable.e9, R.drawable.e10,
                        R.drawable.e11, R.drawable.e12, R.drawable.e13, R.drawable.e14,
                        R.drawable.e15};
        total = resArray.length;
    }
	private void initView()
    {
        indexOfTotalTV = (TextView) findViewById(R.id.image_index_of_total);
        viewPager = (ViewPager) findViewById(R.id.operation_viewpager);
        initPageAdapter();
    }

PagerAdapter的初始化

private void initPageAdapter()
    {
        pagerAdapter = new PagerAdapter()
        {
            //獲取當前界面個數
            @Override
            public int getCount()
            {
                return resArray.length;
            }

            //判斷是否由對象生成頁面
            @Override
            public boolean isViewFromObject(View view, Object object)
            {
                return view == object;
            }

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

            //返回一個對象
            @Override
            public Object instantiateItem(ViewGroup container, int position)
            {
                ImageView imageView = new ImageView(OperationActivity.this);
                imageView.setImageResource(resArray[position]);
                container.addView(imageView);
                return imageView;
            }
        };
        viewPager.setAdapter(pagerAdapter);
        viewPager.setOnPageChangeListener(new GuidePageChangeListener());
        // 默認
        viewPager.setCurrentItem(0);
        indexOfTotalTV.setText(1 + "/" + total);
    }

監聽page變化，顯示index

public class GuidePageChangeListener implements ViewPager.OnPageChangeListener
    {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels)
        {
        }

        //頁面滑動完成後執行
        @Override
        public void onPageSelected(int position)
        {
            indexOfTotalTV.setText(position + 1 + "/" + total);
        }

        //監聽頁面的狀態，0--靜止  1--滑動   2--滑動完成
        @Override
        public void onPageScrollStateChanged(int state)
        {
        }
    }