Android 使用Adapter介面卡模式實現無線輪播BannerView

摘要： 效果圖.gif 程式碼實現 自定義ViewPager public class BannerViewPager extends ViewPager { private BannerAdapter mAdapter; pub...

程式碼實現

自定義ViewPager

public class BannerViewPager extends ViewPager {

private BannerAdapter mAdapter;

public BannerViewPager(Context context) {
super(context);
}

public BannerViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}

public void setAdapter(BannerAdapter adapter) {
this.mAdapter = adapter;
setAdapter(newBannerPagerAdapter());
}

//ViewPager在滑動的時候會一直不斷的建立和銷燬子View所以它不會有記憶體洩露的情況出現
classBannerPagerAdapter extends PagerAdapter{

@Override
public int getCount() {
//為了實現無線迴圈ViewPager這裡設定ViewPager的最大值為Int的最大型別
return Integer.MAX_VALUE;
}

@Override
public boolean isViewFromObject(View view, Object object) {
//官方推薦 這麼寫
return view==object;
}

//載入viewPager的子view
@Override
public Object instantiateItem(ViewGroup container, int position) {
View itemView= mAdapter.getView(position);
container.addView(itemView);
returnitemView;
}


//銷燬ViewPager的只View
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
object=null;
}
}
}

建立Adapter

public abstract class BannerAdapter {
public abstract View getView(int position);
}

layout佈局程式碼

<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<com.example.administrator.allynmvp.view.BannerViewPager
android:id="@+id/banner_vp"
android:layout_width="match_parent"
android:layout_height="150dp">

</com.example.administrator.allynmvp.view.BannerViewPager>

<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent">

</ListView>

</LinearLayout>

初始化載入顯示

public class MainActivity extends AppCompatActivity implements ViewControl {

MusicDataPresenter musicDataPresenter;
ListView listView;
ProgressBar progressBar;
TextView tvError;
BannerViewPager mBannerVp;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getBannerData();
}
public void getBannerData() {
//這裡通過網路載入無效廣告輪播的圖片
//初始化控制元件
mBannerVp.setAdapter(new BannerAdapter() {
@Override
public View getView(int position) {
//這個可以是一個ImageView也可以是一個佈局檔案 穿一個View進去就可以這就是介面卡模式的好處
ImageView imageView=new ImageView(MainActivity.this);
imageView.setBackgroundResource(R.mipmap.ic_launcher);
return imageView;
}
});
}

此文章後續會增加更多的程式碼解釋和擴充套件 敬請期待~~~