在近期使用Glide4.0+版本的时候，需要进行图片加载进度的监听，于是查找各种资料实现该功能，便有了这篇记录。

一、准备工作

笔者Glide为：

 //Glide4.7.1 : https://github.com/bumptech/glide
    implementation('com.github.bumptech.glide:glide:4.7.1') {
        //Glide4，对sdk版本有限制，需要exclude  support库
        //https://muyangmin.github.io/glide-docs-cn/doc/download-setup.html
        exclude group: "com.android.support"
    }
    annotationProcessor 'com.github.bumptech.glide:compiler:4.7.1'

 //okhttp + 拦截器
    api 'com.squareup.okhttp3:okhttp:3.4.1'
    api 'com.github.bumptech.glide:okhttp3-integration:4.3.1'

二、具体实现

大致思路：通过Okhttp的拦截器，监听图片Url的加载进度(需要自己实现逻辑计算)，并回调！
1，步骤1，将OkHttpUrlLoader添加到项目：

/**
 * A simple model loader for fetching media over http/https using OkHttp.
 */
public class OkHttpUrlLoader implements ModelLoader<GlideUrl, InputStream> {

    private final Call.Factory client;

    // Public API.
    @SuppressWarnings("WeakerAccess")
    public OkHttpUrlLoader(Call.Factory client) {
        this.client = client;
    }

    @Override
    public boolean handles(GlideUrl url) {
        return true;
    }

    @Override
    public LoadData<InputStream> buildLoadData(GlideUrl model, int width, int height,
                                               Options options) {
        return new LoadData<>(model, new OkHttpStreamFetcher(client, model));
    }

    /**
     * The default factory for {@link OkHttpUrlLoader}s.
     */
    // Public API.
    @SuppressWarnings("WeakerAccess")
    public static class Factory implements ModelLoaderFactory<GlideUrl, InputStream> {
        private static volatile Call.Factory internalClient;
        private final Call.Factory client;

        private static Call.Factory getInternalClient() {
            if (internalClient == null) {
                synchronized (Factory.class) {
                    if (internalClient == null) {
                        internalClient = new OkHttpClient();
                    }
                }
            }
            return internalClient;
        }

        /**
         * Constructor for a new Factory that runs requests using a static singleton client.
         */
        public Factory() {
            this(getInternalClient());
        }

        /**
         * Constructor for a new Factory that runs requests using given client.
         *
         * @param client this is typically an instance of {@code OkHttpClient}.
         */
        public Factory(Call.Factory client) {
            this.client = client;
        }

        @Override
        public ModelLoader<GlideUrl, InputStream> build(MultiModelLoaderFactory multiFactory) {
            return new OkHttpUrlLoader(client);
        }

        @Override
        public void teardown() {
            // Do nothing, this instance doesn't own the client.
        }
    }
}

2，步骤2，将OkHttpStreamFetcher添加到项目：

/**
 * Fetches an {@link InputStream} using the okhttp library.
 */
public class OkHttpStreamFetcher implements DataFetcher<InputStream>,
        okhttp3.Callback {
    private static final String TAG = "OkHttpFetcher";
    private final Call.Factory client;
    private final GlideUrl url;
    @SuppressWarnings("WeakerAccess")
    @Synthetic
    InputStream stream;
    @SuppressWarnings("WeakerAccess")
    @Synthetic
    ResponseBody responseBody;
    private volatile Call call;
    private DataCallback<? super InputStream> callback;

    // Public API.
    @SuppressWarnings("WeakerAccess")
    public OkHttpStreamFetcher(Call.Factory client, GlideUrl url) {
        this.client = client;
        this.url = url;
    }

    @Override
    public void loadData(Priority priority, final DataCallback<? super InputStream> callback) {
        Request.Builder requestBuilder = new Request.Builder().url(url.toStringUrl());
        for (Map.Entry<String, String> headerEntry : url.getHeaders().entrySet()) {
            String key = headerEntry.getKey();
            requestBuilder.addHeader(key, headerEntry.getValue());
        }
        Request request = requestBuilder.build();
        this.callback = callback;

        call = client.newCall(request);
        if (Build.VERSION.SDK_INT != Build.VERSION_CODES.O) {
            call.enqueue(this);
        } else {
            try {
                // Calling execute instead of enqueue is a workaround for #2355, where okhttp throws a
                // ClassCastException on O.
                onResponse(call, call.execute());
            } catch (IOException e) {
                onFailure(call, e);
            } catch (ClassCastException e) {
                // It's not clear that this catch is necessary, the error may only occur even on O if
                // enqueue is used.
                onFailure(call, new IOException("Workaround for framework bug on O", e));
            }
        }
    }

    @Override
    public void onFailure(@NonNull Call call, @NonNull IOException e) {
        if (Log.isLoggable(TAG, Log.DEBUG)) {
            Log.d(TAG, "OkHttp failed to obtain result", e);
        }

        callback.onLoadFailed(e);
    }

    @Override
    public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
        responseBody = response.body();
        if (response.isSuccessful()) {
            long contentLength = Preconditions.checkNotNull(responseBody).contentLength();
            stream = ContentLengthInputStream.obtain(responseBody.byteStream(), contentLength);
            callback.onDataReady(stream);
        } else {
            callback.onLoadFailed(new HttpException(response.message(), response.code()));
        }
    }

    @Override
    public void cleanup() {
        try {
            if (stream != null) {
                stream.close();
            }
        } catch (IOException e) {
            // Ignored
        }
        if (responseBody != null) {
            responseBody.close();
        }
        callback = null;
    }

    @Override
    public void cancel() {
        Call local = call;
        if (local != null) {
            local.cancel();
        }
    }

    @NonNull
    @Override
    public Class<InputStream> getDataClass() {
        return InputStream.class;
    }

    @NonNull
    @Override
    public DataSource getDataSource() {
        return DataSource.REMOTE;
    }
}

3，步骤3，自定义拦截器和回调接口：

public interface ProgressListener {
    void onProgress(int progress);
}

public class ProgressInterceptor implements Interceptor{
    public static final Map<String, ProgressListener> LISTENER_MAP = new HashMap<>();

    public static void addListener(String url, ProgressListener listener) {
        LISTENER_MAP.put(url, listener);
    }

    public static void removeListener(String url) {
        LISTENER_MAP.remove(url);
    }

    @Override
    public Response intercept(Chain chain) throws IOException {
        Request request = chain.request();
        Response response = chain.proceed(request);
        String url = request.url().toString();
        ResponseBody body = response.body();
        Response newResponse = response.newBuilder().body(new ProgressResponseBody(url, body)).build();
        return newResponse;
    }
}

4，步骤4，计算加载进度，并在自定义的拦截器中使用：

public class ProgressResponseBody extends ResponseBody {

    private static final String TAG = "ProgressResponseBody";

    private BufferedSource bufferedSource;

    private ResponseBody responseBody;

    private ProgressListener listener;

    public ProgressResponseBody(String url, ResponseBody responseBody) {
        this.responseBody = responseBody;
        listener = ProgressInterceptor.LISTENER_MAP.get(url);
    }

    @Override
    public MediaType contentType() {
        return responseBody.contentType();
    }

    @Override
    public long contentLength() {
        return responseBody.contentLength();
    }

    @Override
    public BufferedSource source() {
        if (bufferedSource == null) {
            bufferedSource = Okio.buffer(new ProgressSource(responseBody.source()));
        }
        return bufferedSource;
    }

    private class ProgressSource extends ForwardingSource {

        long totalBytesRead = 0;

        int currentProgress;

        ProgressSource(Source source) {
            super(source);
        }

        @Override
        public long read(Buffer sink, long byteCount) throws IOException {
            long bytesRead = super.read(sink, byteCount);
            long fullLength = responseBody.contentLength();
            if (bytesRead == -1) {
                totalBytesRead = fullLength;
            } else {
                totalBytesRead += bytesRead;
            }
            int progress = (int) (100f * totalBytesRead / fullLength);
            Log.d(TAG, "download progress is " + progress);
            if (listener != null && progress != currentProgress) {
                listener.onProgress(progress);
            }
            if (listener != null && totalBytesRead == fullLength) {
                listener = null;
            }
            currentProgress = progress;
            return bytesRead;
        }
    }

}

5，在Glide中启用：

@GlideModule
public class MyGlideModel extends AppGlideModule {

    public MyGlideModel() {
        super();
    }

    @Override
    public boolean isManifestParsingEnabled() {
        return super.isManifestParsingEnabled();
    }

    @Override
    public void applyOptions(@NonNull Context context, @NonNull GlideBuilder builder) {
        super.applyOptions(context, builder);
    }

    @Override
    public void registerComponents(@NonNull Context context, @NonNull Glide glide, @NonNull Registry registry) {
//        super.registerComponents(context,glide,registry);

        OkHttpClient okHttpClient = new OkHttpClient.Builder()
                .addInterceptor(new ProgressInterceptor())
                .build();

        registry.replace(GlideUrl.class, InputStream.class, new OkHttpUrlLoader.Factory(okHttpClient));
    }
}

三、项目使用

public class Glide4Activity extends BaseActivity {
    private static final String TAG = "Glide4Activity";

    String imgUrl = "http://img5.adesk.com/5ab8ce65e7bce736a953c83c?imageMogr2/thumbnail/!720x1280r/gravity/Center/crop/720x1280";
    @BindView(R.id.glide_iv)
    ImageView mGlideIv;
    ProgressDialog progressDialog;
    @Override
    public int getLayoutId() {
        return R.layout.activity_glide;
    }

    @Override
    public void initView() {
        progressDialog = new ProgressDialog(this);
        progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        progressDialog.setMessage("加载中");
        ProgressInterceptor.addListener(imgUrl, new ProgressListener() {
            @Override
            public void onProgress(int progress) {
                Log.d(TAG, "onProgress: " + progress);
                progressDialog.setProgress(progress);
            }
        });

        SimpleTarget<Drawable> simpleTarge = new SimpleTarget<Drawable>() {
            @Override
            public void onResourceReady(@NonNull Drawable resource, @Nullable Transition<? super Drawable> transition) {
                progressDialog.dismiss();
                mGlideIv.setImageDrawable(resource);
                Log.d(TAG, "onResourceReady: ");
                ProgressInterceptor.removeListener(imgUrl);
            }

            @Override
            public void onStart() {
                super.onStart();
                Log.d(TAG, "onStart: ");
                progressDialog.show();
            }
        };
        GlideApp.with(this)
                .load(imgUrl)
                .diskCacheStrategy(DiskCacheStrategy.NONE)//不使用缓存
                .skipMemoryCache(true)
                .into(simpleTarge);

    }


}

image.png

加载进度，美女镇楼.gif

本文仅为记录，详细分析参考：郭霖大神Glide系列文章