參考原文：Android圖片載入框架最全解析（七），實現帶進度的Glide圖片載入功能

擴充套件目標

對Glide進行功能擴充套件，使其支援監聽圖片下載進度的功能

開始

dependencies { 
    compile 'com.github.bumptech.glide:glide:3.7.0' 
    compile 'com.squareup.okhttp3:okhttp:3.9.0' 
}

替換通訊元件

public class MyGlideModule implements GlideModule { 
    @Override 
    public
 
 void applyOptions(Context context, GlideBuilder builder) { 
    } 

    @Override 
    public void registerComponents(Context context, Glide glide) { 
        glide.register(GlideUrl.class, InputStream.class, new OkHttpGlideUrlLoader.Factory());
    } 
}

現下載進度監聽

空的攔截器

public class ProgressInterceptor
 
 implements Interceptor { 

    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); 
        return response; 
    } 

}

public class MyGlideModule implements GlideModule { 
    @Override 
    public void applyOptions(Context context, GlideBuilder builder) { 
    } 

    @Override 
    public void registerComponents(Context context, Glide glide) { 
        OkHttpClient.Builder builder = new OkHttpClient.Builder(); 
        builder.addInterceptor(new ProgressInterceptor()); 
        OkHttpClient okHttpClient = builder.build(); 
        glide.register(GlideUrl.class, InputStream.class, new OkHttpGlideUrlLoader.Factory(okHttpClient));
    } 
}

這裡我們建立了一個OkHttpClient.Builder，然後呼叫addInterceptor()方法將剛才建立的ProgressInterceptor新增進去，最後將構建出來的新OkHttpClient物件傳入到OkHttpGlideUrlLoader.Factory中即可

public class ProgressInterceptor implements Interceptor { 

    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); 
        return response; 
    } 

}

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;
        }
    }

}

  @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; 
    } 

進度顯示

public class MainActivity extends AppCompatActivity {

    String url = "http://guolin.tech/book.png";

    ImageView image;

    ProgressDialog progressDialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        image = (ImageView) findViewById(R.id.image);
        progressDialog = new ProgressDialog(this);
        progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        progressDialog.setMessage("載入中"); 
    }

    public void loadImage(View view) {
        ProgressInterceptor.addListener(url, new ProgressListener() {
            @Override
            public void onProgress(int progress) {
                progressDialog.setProgress(progress);
            }
        });
        Glide.with(this)
             .load(url)
             .diskCacheStrategy(DiskCacheStrategy.NONE)
             .override(Target.SIZE_ORIGINAL, Target.SIZE_ORIGINAL)
             .into(new GlideDrawableImageViewTarget(image) {
                 @Override
                 public void onLoadStarted(Drawable placeholder) {
                     super.onLoadStarted(placeholder);
                     progressDialog.show();
                 }

                 @Override 
                 public void onResourceReady(GlideDrawable resource, GlideAnimation<? super GlideDrawable> animation) {
                     super.onResourceReady(resource, animation);
                     progressDialog.dismiss();
                     ProgressInterceptor.removeListener(url);
                 }
             });
    }