这是英文文档的第三部分：THIRD PARTY LIBRARIES

Using Other Network Layers

By default, the image pipeline uses the HttpURLConnection networking library
bundled with Android. Apps may have their own network layer they may wish to use instead.

Using OkHttp

OkHttp is a popular open-source networking library. The image pipeline has a backend that uses OkHttp instead of the Android
default.

In order to use it, the dependencies section of your build.gradle file needs to be changed. Donot use
the Gradle dependencies given on the download page. Use these instead:

dependencies {
  // your project‘s other dependencies
  compile "com.facebook.fresco:fresco:0.2.0+"
  compile "com.facebook.fresco:imagepipeline-okhttp:0.2.0+"
}

You must also configure the image pipeline a little differently. Instead of usingImagePipelineConfig.newBuilder, use OkHttpImagePipelineConfigFactory instead:

Context context;
OkHttpClient okHttpClient; // build on your own
ImagePipelineConfig config = OkHttpImagePipelineConfigFactory
    .newBuilder(context, okHttpClient)
    . // other setters
    . // setNetworkFetcher is already called for you
    .build();
Fresco.initialize(context, config);

Using your own network fetcher (optional)

For complete control on how the networking layer should behave, you can provide one for your app. You must subclass NetworkFetcher,
which controls communications to the network. You can also optionally subclass FetchState,
which is a data structure for request-specific information.

Our default implementation for HttpURLConnection can be used as an example. See its
source code.

You must pass your network producer to the image pipeline when configuring it:

ImagePipelineConfig config = ImagePipelineConfig.newBuilder()
  .setNetworkFetcher(myNetworkFetcher);
  . // other setters
  .build();
Fresco.initialize(context, config);

Using Other Image Loaders

Drawee is not tied to a particular image loading mechanism and can be used with other image loaders.

However, some of its features are only available on the Fresco image pipeline. Any feature in the preceding pages that required using an ImageRequest or configuration may
not work with a different loader.

Using Drawee with Volley ImageLoader

We have an backend for Drawee that allows Volley‘s ImageLoader to be used instead of Fresco‘s
image pipeline.

We only recommend this for apps that already have a significant investment in Volley ImageLoader.

In order to use it, the dependencies section of your build.gradle file needs to be changed. Donot use
the Gradle dependencies given on the download page. Use this instead:

dependencies {
  // your project‘s other dependencies
  compile: "com.facebook.fresco:drawee-volley:0.2.0+"
}

Initializing with Volley ImageLoader

Do not call Fresco.initialize. You must do yourself for Volley what it does with the image pipeline:

Context context;
ImageLoader imageLoader; // build yourself
VolleyDraweeControllerBuilderSupplier mControllerBuilderSupplier
    = new VolleyDraweeControllerBuilderSupplier(context, imageLoader);
SimpleDraweeView.initialize(mControllerBuilderSupplier);

Do not let the VolleyDraweeControllerBuilderSupplier out of scope; you need it to build controllers, unless you always use SimpleDraweeView.setImageURI.

Using DraweeControllers with Volley ImageLoader

Instead of calling Fresco.newControllerBuilder, call

VolleyController controller = mControllerBuilderSupplier
    .newControllerBuilder()
    . // setters
    .build();
mSimpleDraweeView.setController(controller);

Using Drawee with other image loaders

No other Drawee backends have been built yet, though it is possible to do so using the Volley
example as a model.

第5部分：CONTRIBUTING TO FRESCO

Building from Source

You should only build from source if you need to modify Fresco code itself. Most applications should simply include Fresco
in their project.

Prerequisites

The following tools must be installed on your system in order to build Fresco:

1. The Android SDK
2. From the Android SDK Manager, install the Support Library and the Support Repository. Both are found in the Extras section.
3. The Android NDK. Version 10c or later is required.
4. The git version control system.

You don‘t need to download Gradle itself; the build scripts or Android Studio will do that for you.

Fresco does not support source builds with Eclipse, Ant, or Maven. We do not plan to ever add such support. Maven projects can still include Fresco,
and we hope to later add Eclipse and Ant support.

Configuring Gradle

Both command-line and Android Studio users need to edit the gradle.properties file. This is normally located in your home directory, in a subdirectory called .gradle.
If it is not already there, create it.

On Unix-like systems, including Mac OS X, add a line like this:

ndk.path=/path/to/android_ndk/r10d

On Windows systems, add a line like this:

ndk.path=C\:\\path\\to\\android_ndk\\r10d

Windows‘ backslashes and colons need to be escaped in order for Gradle to read them correctly.

Getting the source

git clone https://github.com/facebook/fresco.git

This will create a directory fresco where the code will live.

Building from the Command Line

On Unix-like systems, cd to the directory containing Fresco. Run the following command:

./gradlew build

On Windows, open a Command Prompt, cd to the directory containing Fresco, and type in this command:

gradlew.bat build

Building from Android Studio

From Android Studio‘s Quick Start dialog, click Import Project. Navigate to the directory containing Fresco and click on the build.gradle file.

Android Studio should build Fresco automatically.

Offline builds

The first time you build Fresco, your computer must be connected to the Internet. Incremental builds can use Gradle‘s --offline option.

Contributing code upstream

Please see our CONTRIBUTING page.