第二十一篇 Android listview异步加载本地视频缩略图

最近项目中需要在listview上加载视频缩略图，如果直接使用ThumbnailUtils类获取会出现oom，然后参考了网上这边

文章，感觉不错，稍微做了下调整,这里做个记录，方便后续复用.

MyVideoThumbLoader类：

public class MyVideoThumbLoader {

// 创建cache
private LruCache<String, Bitmap> lruCache;
private Context mContext;

public MyVideoThumbLoader(Context context) {
mContext = context;
int maxMemory = (int) Runtime.getRuntime().maxMemory();// 获取最大的运行内存
int maxSize = maxMemory / 4;
// 拿到缓存的内存大小
lruCache = new LruCache<String, Bitmap>(maxSize) {
@Override
protected int sizeOf(String key, Bitmap value) {
// 这个方法会在每次存入缓存的时候调用
return value.getByteCount();
}
};
}

public void addVideoThumbToCache(String path, Bitmap bitmap) {
if (getVideoThumbToCache(path) == null) {
// 当前地址没有缓存时，就添加

lruCache.put(path, bitmap);
}
}

public Bitmap getVideoThumbToCache(String path) {

return lruCache.get(path);

}

public void showThumbByAsynctack(String path, MyImageView imgview) {

if (getVideoThumbToCache(path) == null) {
// 异步加载
new MyBobAsynctack(imgview, path).execute(path);
} else {
imgview.setImageBitmap(getVideoThumbToCache(path));
}

}

class MyBobAsynctack extends AsyncTask<String, Void, Bitmap> {
private MyImageView imgView;
private String path;

public MyBobAsynctack(MyImageView imageView, String path) {
this.imgView = imageView;
this.path = path;
}

@Override
protected Bitmap doInBackground(String... params) {

Bitmap bitmap2 = null;

try {

ThumbnailUtils tu = new ThumbnailUtils();

Bitmap bitmap = tu.createVideoThumbnail(params[0],
MediaStore.Video.Thumbnails.MICRO_KIND);

System.out.println("111111path: " + path + "  bitmap: "
+ bitmap);

if (bitmap == null) {

//将drawable转bitmap
bitmap = android.graphics.BitmapFactory.decodeResource(
mContext.getResources(),
R.drawable.icon_video);

System.out.println("5555555path: " + path + "  bitmap: "
+ bitmap);
}

// //直接对Bitmap进行缩略操作，最后一个参数定义为OPTIONS_RECYCLE_INPUT ，来回收资源

bitmap2 = tu.extractThumbnail(bitmap, 50, 50,
ThumbnailUtils.OPTIONS_RECYCLE_INPUT);
System.out.println("path: " + path + "bitmap2: " + bitmap2);

// 加入缓存中
if (getVideoThumbToCache(params[0]) == null) {
addVideoThumbToCache(path, bitmap2);
}
} catch (Exception e) {
e.printStackTrace();
}

return bitmap2;
}

@Override
protected void onPostExecute(Bitmap bitmap) {
if (imgView.getTag().equals(path)) {// 通过 Tag可以绑定 图片地址和
// imageView，这是解决Listview加载图片错位的解决办法之一
imgView.setImageBitmap(bitmap);
}
}
}
}

<
4000
p>MyImageView类:需要使用MyImageView，不能使用ImageView来显示视频缩略图.

public class MyImageView extends ImageView {

public MyImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}

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

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

@Override
protected void onDraw(Canvas canvas) {
try {
super.onDraw(canvas);
} catch (Exception e) {
System.out.println("trying to use a recycled bitmap");
}
}

}

VideoAdapter类：可根据业务需求自定义.

public class VideoAdapter extends BaseAdapter {

List<FileBean> datas;
private LayoutInflater mInflater;
private int resources;
private Context mContext;
private MyVideoThumbLoader mVideoThumbLoader;

public VideoAdapter(Context mContext, int resources, List<FileBean> datas) {
this.mContext = mContext;
this.resources = resources;
this.datas = datas;
mInflater = LayoutInflater.from(mContext);
mVideoThumbLoader = new MyVideoThumbLoader(mContext);// 初始化缩略图载入方法
}

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

@Override
public Object getItem(int position) {
if (position < 0 || position >= datas.size())
return null;
return datas.get(position);
}

@Override
public long getItemId(int position) {
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
FileBean entity = datas.get(position);
if (convertView == null) {
holder = new ViewHolder();
convertView = mInflater.inflate(resources, parent, false);
holder.fileIcon = (MyImageView) convertView.findViewById(R.id.image);
holder.fileName = (TextView) convertView.findViewById(R.id.name);
holder.time = (TextView) convertView.findViewById(R.id.time);
holder.fileSize = (TextView) convertView.findViewById(R.id.size);
holder.check = (ImageView) convertView.findViewById(R.id.ivCheck);
convertView.setTag(holder);
holder.fileIcon.setTag(entity.getFile().getAbsolutePath());
} else {
holder = (ViewHolder) convertView.getTag();
}

if (entity.getFile().length() <= 0) {
holder.fileIcon.setImageResource(R.drawable.icon_video);
}else{
mVideoThumbLoader.showThumbByAsynctack(entity.getFile().getAbsolutePath(), holder.fileIcon);
}

holder.fileName.setText(entity.getFileName());
holder.time.setText(String.valueOf(entity.getFile().lastModified()));
holder.fileSize.setText(FileUtils.formatSize(String.valueOf(entity.getFileSize())));
holder.check.setVisibility(entity.isChoose() ? View.VISIBLE : View.GONE);

return convertView;
}

class ViewHolder {
MyImageView fileIcon;
TextView fileName;
TextView time;
TextView fileSize;
ImageView check;
}
}