fresco添加http header

今天使用fresco时，项目中在加载图片时添加了防盗链，需要在获取图片时添加header信息，研究了下fresco如何添加header，解决方案如下：
1、新建一个类ElnImageDownloaderFetcher，继承HttpUrlConnectionNetworkFetcher
2、将HttpUrlConnectionNetworkFetcher类的代码拷贝到新类
3、重写HttpURLConnection的获取
4、将ElnImageDownloaderFetcher配置到ImagePipelineConfig
代码实现如下：
ElnImageDownloaderFetcher.java

public class ElnImageDownloaderFetcher extends HttpUrlConnectionNetworkFetcher {
    private static final int NUM_NETWORK_THREADS = 3;
    public static final int DEFAULT_HTTP_CONNECT_TIMEOUT = 5000;
    public static final int DEFAULT_HTTP_READ_TIMEOUT = 20000;
    private final ExecutorService mExecutorService;

    public ElnImageDownloaderFetcher() {
        mExecutorService = Executors.newFixedThreadPool(NUM_NETWORK_THREADS);
    }

    @Override
    public void fetch(final FetchState fetchState, final Callback callback) {
        final Future future = mExecutorService.submit(
                new Runnable() {
                    @Override
                    public void run() {
                        HttpURLConnection connection = null;
                        Uri uri = fetchState.getUri();
                        String scheme = uri.getScheme();
                        String uriString = fetchState.getUri().toString();
                        while (true) {
                            String nextUriString;
                            String nextScheme;
                            InputStream is;
                            try {
                                connection = createConnection(uriString);
                                nextUriString = connection.getHeaderField("Location");
                                nextScheme = (nextUriString == null) ? null : Uri.parse(nextUriString).getScheme();
                                if (nextUriString == null || nextScheme.equals(scheme)) {
                                    is = connection.getInputStream();
                                    callback.onResponse(is, -1);
                                    break;
                                }
                                uriString = nextUriString;
                                scheme = nextScheme;
                            } catch (Exception e) {
                                callback.onFailure(e);
                                break;
                            } finally {
                                if (connection != null) {
                                    connection.disconnect();
                                }
                            }
                        }

                    }
                });
        fetchState.getContext().addCallbacks(
                new BaseProducerContextCallbacks() {
                    @Override
                    public void onCancellationRequested() {
                        if (future.cancel(false)) {
                            callback.onCancellation();
                        }
                    }
                });
    }

    protected HttpURLConnection createConnection(String url) throws IOException {
        String encodedUrl = Uri.encode(url, "@#&=*+-_.,:!?()/~\'%");
        HttpURLConnection conn = (HttpURLConnection)(new URL(encodedUrl)).openConnection();
        conn.setConnectTimeout(DEFAULT_HTTP_CONNECT_TIMEOUT);
        conn.setReadTimeout(DEFAULT_HTTP_READ_TIMEOUT);
        if (BaseRequest.REFERER_OPEN) {
            conn.setRequestProperty(BaseRequest.getRefererKey(), BaseRequest.getRefererValue());
        }
        return conn;
    }
}

重点在方法createConnection里，设置了referer信息

然后带配置初始化fresco：

private void initFresco(){
        DiskCacheConfig diskCacheConfig = DiskCacheConfig.newBuilder()
                .setBaseDirectoryPath(new File(MultiCard.getInstance(this).getRootDir()))
                .setBaseDirectoryName("image_cache")
                .setMaxCacheSize(50 * ByteConstants.MB)
                .setMaxCacheSizeOnLowDiskSpace(10 * ByteConstants.MB)
                .setMaxCacheSizeOnVeryLowDiskSpace(2 * ByteConstants.MB)
                .build();
        ImagePipelineConfig config = ImagePipelineConfig.newBuilder(this)
                .setNetworkFetcher(new ElnImageDownloaderFetcher())
                .setMainDiskCacheConfig(diskCacheConfig).build();
        Fresco.initialize(this, config);
    }

重点是给ImagePipelineConfig 配置了NetworkFetcher。

OK，解决，记录一下。