图片二次采样

最新推荐文章于 2022-09-14 10:25:34 发布

原创最新推荐文章于 2022-09-14 10:25:34 发布 · 167 阅读

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本文介绍了一个用于Android平台的图片加载与缓存工具类ImgUtils。该工具类能够从网络下载图片并进行本地缓存，同时支持图片的二次采样以减少内存消耗。在图片不存在于本地缓存时，它会在后台线程中下载图片，并将其保存到SD卡。

public class ImgUtils {
    private static ImgUtils imgUtils = null ;
    private ImgUtils(){}
    public static ImgUtils getImgUtils() {
        if (imgUtils == null){
            imgUtils = new ImgUtils();
        }
        return imgUtils;
    }
    private Handler handler = new Handler();
    public void loadImg(String img , ImageView imgview){
        String name = img.substring(img.lastIndexOf("/") + 1);
        File file = new File(Environment.getExternalStorageDirectory() + "/" + name);
        if (file.exists()){
            Bitmap bitmap = douImg(file);
            imgview.setImageBitmap(bitmap);
        }else{
            new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        URL url = new URL(img);
                        HttpURLConnection con = (HttpURLConnection) url.openConnection();
                        con.setRequestMethod("GET");
                        con.setReadTimeout(5000);
                        con.setConnectTimeout(5000);
                        if (con.getResponseCode() == 200) {
                            InputStream is = con.getInputStream();
                            BufferedInputStream bis = new BufferedInputStream(is);
                            Bitmap b = BitmapFactory.decodeStream(bis);
                            is.close();bis.close();con.disconnect();
                            b.compress(Bitmap.CompressFormat.JPEG,100,new FileOutputStream(file));
                            handler.post(new Runnable() {
                                @Override
                                public void run() {
                                    imgview.setImageBitmap(douImg(file));
                                }
                            });
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }
    }
    //TODO  图片的二次采样
    private Bitmap douImg(File file) {
        BitmapFactory.Options op = new BitmapFactory.Options();
        op.inSampleSize = 4 ;
        Bitmap.Config fig = Bitmap.Config.RGB_565;
        Bitmap b = BitmapFactory.decodeFile(file.getAbsolutePath(), op);
        return b ;
    }

}