Retrofit源码分析

Retrofit

Retrofit发起一个简单地网络请求

导入retrofit

compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'
compile ('com.squareup.retrofit2:adapter-rxjava:2.0.0'){
    exclude group: 'io.reactivex', module: 'rxjava'
}//支持rxjava
compile ('io.reactivex:rxandroid:1.2.1'){
    exclude group: 'io.reactivex', module: 'rxjava'
}

新建一个api

public interface Api {
    @GET("api/v1/abc/def")
    Observable getTotal();

    @GET("api/v1/mnl/xyz")
    Observable getMoneyTotal();
}

初始化Retrofit和Okhttp

初始化Okhttp

private OkHttpClient initOkHttpClient(){
    OkHttpClient client = new OkHttpClient.Builder()
            .addInterceptor(new Interceptor() {
                @Override
                public Response intercept(Chain chain) throws IOException {
                    Request r = chain.request().newBuilder()
                            .addHeader("x-device-info","HUAWEI/7.0/").build();
                    return chain.proceed(r);
                }
            }).build();
    return client;
}

初始化Retrofit

Retrofit retrofit = new Retrofit.Builder()
        .baseUrl("http://****.com/")
        .addConverterFactory(GsonConverterFactory.create())
        .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
        .client(initOkHttpClient())
        .build();

RxJavaCallAdapterFactory.createWithScheduler 接受Scheduler
可以在发起请求的时候指定Schedulers.io();

发起网络请求

Api api = retrofit.create(Api.class);
Observable observable = api.getTotal();
observable.subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(new Subscriber() {
    @Override
    public void onCompleted() {

    }

    @Override
    public void onError(Throwable e) {
        e.printStackTrace();
    }

    @Override
    public void onNext(ResponseBody responseBody) {
        try {
            Log.e(TAG, "call: "+ new String(responseBody.bytes()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
});

看完上面代码产生以下疑问

• API 接口怎么映射到对应的请求retrofit.create(Api.class)
• ConverterFactory和ConverterFactory怎么工作的
• Retrofit怎么支持Rxjava的

解决问题最粗暴的方法断点跟踪，大致跟下代码。
Copy源代码到工程里面，导入对应的包

compile 'com.squareup.okhttp3:okhttp:3.2.0'
compile 'com.google.code.gson:gson:2.6.1'
compile 'io.reactivex:rxjava:1.2.1'
compile 'com.google.code.findbugs:jsr305:3.0.0'

流程图

1. 先来看看create(Api.class)的代码

public  T create(final Class service) {
 
    return (T) Proxy.newProxyInstance(service.getClassLoader(), new Class[] { service },
      new InvocationHandler() {
        private final Platform platform = Platform.get();

        @Override public Object invoke(Object proxy, Method method, @Nullable Object[] args)
            throws Throwable {
          Log.e(TAG, "invoke: "+ method.getName() );
          // If the method is a method from Object then defer to normal invocation.
              if (method.getDeclaringClass() == Object.class) {
              return method.invoke(this, args);
            }
              ServiceMethod serviceMethod =
              (ServiceMethod) loadServiceMethod(method);
          OkHttpCall