java - Picasso - 自定义 RequestHandler 不会在磁盘上缓存图像

Question

我需要从某些服务加载和缓存图像。例如，没有这样的服务，但它显示了我想要实现的目标。

我的问题是图像没有缓存在磁盘上。没有通常的文件夹/data/data/myapp/cache/picasso-cache。

如何从 RequestHandler 访问缓存。甚至有可能或者编写自定义下载器会更好？

请求处理程序

public class CustomRequestHandler extends RequestHandler {

    private static final List<String> PATHS = Arrays.asList("http://somelink/someimage1.png",
            "http://somelink/someimage2.png",
            "http://somelink/someimage3.png");

    private Iterator<String> pathIterator = PATHS.iterator();

    @Override
    public boolean canHandleRequest(Request data) {
        return data.uri.toString().contains("custom");
    }

    @Override
    public Result load(Request request, int networkPolicy) throws IOException {
        if (!pathIterator.hasNext()) {
            pathIterator = PATHS.iterator();
        }

        Bitmap bitmap = downloadFullFromUrl(pathIterator.next());
        Result result = new Result(bitmap, Picasso.LoadedFrom.NETWORK);
        return result;
    }

    private static Bitmap downloadFullFromUrl(String imageFullURL) {
        Bitmap bm = null;
        try {
            URL url = new URL(imageFullURL);
            URLConnection ucon = url.openConnection();
            InputStream is = ucon.getInputStream();
            BufferedInputStream bis = new BufferedInputStream(is);
            ByteArrayBuffer baf = new ByteArrayBuffer(50);
            int current;
            while ((current = bis.read()) != -1) {
                baf.append((byte) current);
            }
            bm = BitmapFactory.decodeByteArray(baf.toByteArray(), 0,
                    baf.toByteArray().length);
        } catch (IOException e) {
            Log.d("ImageManager", "Error: " + e);
        }
        return bm;
    }
}

用法:

Picasso picasso = Picasso.Builder(application)
                .addRequestHandler(requestHandler)
                .build();

picasso.load("custom").into(imageView);

Answer 1

正如@sashabelonogov 提到的，您需要将带有请求处理程序的 picasso 实例作为单例实例。我只是通过将它添加到我的应用程序类并在所有地方使用 Picasso.with(Context) 来做到这一点。

public class MyApplication extends Application {

    public void onCreate() {
        super.onCreate();
        Picasso picasso = new Picasso.Builder(getApplicationContext())
                .addRequestHandler(new MyRequestHandler())
                .build();
        Picasso.setSingletonInstance(picasso);
    }
}