android轮播图实现
时间: 2023-09-22 13:07:41 浏览: 57
Android 轮播图实现可以使用 ViewPager 或者第三方库,这里以 ViewPager 为例:
1. 首先在布局文件中添加 ViewPager 和指示器(Indicator):
```
<androidx.viewpager.widget.ViewPager
android:id="@+id/viewPager"
android:layout_width="match_parent"
android:layout_height="200dp"/>
<LinearLayout
android:id="@+id/indicator"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:gravity="center"
android:orientation="horizontal"/>
```
2. 创建一个 Adapter 类,用于管理轮播图的数据和布局:
```
public class BannerAdapter extends PagerAdapter {
private Context mContext;
private List<Integer> mImages;
public BannerAdapter(Context context, List<Integer> images) {
mContext = context;
mImages = images;
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
ImageView imageView = new ImageView(mContext);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setImageResource(mImages.get(position));
container.addView(imageView);
return imageView;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
@Override
public int getCount() {
return mImages.size();
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
}
```
3. 在 Activity 或 Fragment 中设置 ViewPager 和指示器:
```
ViewPager viewPager = findViewById(R.id.viewPager);
LinearLayout indicatorLayout = findViewById(R.id.indicator);
BannerAdapter adapter = new BannerAdapter(this, images);
viewPager.setAdapter(adapter);
for (int i = 0; i < images.size(); i++) {
ImageView imageView = new ImageView(this);
imageView.setImageResource(R.drawable.indicator_selector);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
params.setMargins(10, 0, 10, 0);
indicatorLayout.addView(imageView, params);
}
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}
@Override
public void onPageSelected(int position) {
for (int i = 0; i < indicatorLayout.getChildCount(); i++) {
ImageView imageView = (ImageView) indicatorLayout.getChildAt(i);
imageView.setSelected(i == position);
}
}
@Override
public void onPageScrollStateChanged(int state) {}
});
```
这样就完成了一个简单的 Android 轮播图的实现。
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