Retrofit

简单的实例

public interface MyInterface {
    @GET("...／...")
    Call> getCall();
}

public class RetrofitS {
    public void MyRetrofit() throws IOException {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://xxx.xxx.com/") // 设置网络请求的Url地址
                .addConverterFactory(GsonConverterFactory.create()) // 设置数据解析器
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) // 支持RxJava平台
                .build();

        MyInterface myInterface = retrofit.create(MyInterface.class);

        Call call = myInterface.getCall();
        //retrofit同步请求
        call.execute();

        call.enqueue(new retrofit2.Callback() {
            @Override
            public void onResponse(Call call, retrofit2.Response response) {
                System.out.println(response.body());
            }

            @Override
            public void onFailure(Call call, Throwable throwable) {
                System.out.println("请求失败");
            }
        });
    }

}

@GET 完整URL = baseURL + get请求的路径
{}表示动态参数中获取
@Path("user") 表示参数为空的默认值
addConverterFactory用来映射我们response对象的解析器
service.listRepos 返回Call是OkHttp中的，在调用它的异步接口

代理

静态代理

静态代理.png

动态代理

jdk动态代理

InvocationHandler.png

public interface Subject{
    void shopping();
}
public class Proxy implements InvocationHandler {
    private Object target;//要代理的真实对象
    public Proxy(Subject target){
        this.target = target;
    }
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("proxy:"+proxy.getClass().getName());
        System.out.println("before...");
        method.invoke(target, args);
        System.out.println("after...");
        return null;
    }
}

public class Client {
    public static void main(String[] args) {
        Subject man = new Man();
        Proxy p = new Proxy(man);
        //通过java.lang.reflect.newProxyInstance(...)方法获得真实对象的代理对象
        Subject subject = (Subject)java.lang.reflect.Proxy.
                newProxyInstance(man.getClass().getClassLoader(),
                        man.getClass().getInterfaces(), p);
        //通过代理对象调用真实对象相关接口中实现的方法，这个时候就会跳转到这个代理对象所关联的handler的invoke()方法去执行
        subject.shopping();
        //获得真实对象的代理对象所对应的Class对象的名称,用字符串表示
        System.out.println(subject.getClass().getName());
    }
}

动态代理总结 .png

CGLIB

Retrofit8个步骤

1. build初始化,Platform.get()反射获得安卓平台

public static final class Builder {
    private Platform platform;
    private okhttp3.Call.Factory callFactory;
    private HttpUrl baseUrl;
    private List converterFactories = new ArrayList<>();
    private List adapterFactories = new ArrayList<>();
    private Executor callbackExecutor;
    private boolean validateEagerly;

    Builder(Platform platform) {
      this.platform = platform;
      // Add the built-in converter factory first. This prevents overriding its behavior but also
      // ensures correct behavior when using converters that consume all types.
      converterFactories.add(new BuiltInConverters());
    }

    public Builder() {
      this(Platform.get());
    }

  public Retrofit build() {
      if (baseUrl == null) {
        throw new IllegalStateException("Base URL required.");
      }

      okhttp3.Call.Factory callFactory = this.callFactory;
      if (callFactory == null) {
        callFactory = new OkHttpClient();
      }

      Executor callbackExecutor = this.callbackExecutor;
      if (callbackExecutor == null) {
        callbackExecutor = platform.defaultCallbackExecutor();
      }

      // Make a defensive copy of the adapters and add the default Call adapter.
      List adapterFactories = new ArrayList<>(this.adapterFactories);
      adapterFactories.add(platform.defaultCallAdapterFactory(callbackExecutor));

      // Make a defensive copy of the converters.
      List converterFactories = new ArrayList<>(this.converterFactories);

      return new Retrofit(callFactory, baseUrl, converterFactories, adapterFactories,
          callbackExecutor, validateEagerly);
    }

  static class Android extends Platform {
    @Override public Executor defaultCallbackExecutor() {
      return new MainThreadExecutor();
    }

    @Override CallAdapter.Factory defaultCallAdapterFactory(Executor callbackExecutor) {
      return new ExecutorCallAdapterFactory(callbackExecutor);
    }

    static class MainThreadExecutor implements Executor {
      private final Handler handler = new Handler(Looper.getMainLooper());

      @Override public void execute(Runnable r) {
        handler.post(r);
      }
    }
  }

总结：
Retrofit通过构建模式初始化callFactory,baseUrl,converterFactories,adapterFactories, callbackExecutor, validateEagerly
这些参数的基本信息
callFactory——OkHttpClient
converterFactories——解析器
adapterFactories——平台适配器
callbackExecutor——子线程和主线程切换（handler）
validateEagerly——response是否立即解析

MyInterface myInterface = retrofit.create(MyInterface.class);
create里面通过动态代理生成一个代理对象，通过ServiceMethod拿到注解信息，创建OkHttpCall对象，通过传入ServiceMethod和args

 private okhttp3.Call createRawCall() throws IOException {
    Request request = serviceMethod.toRequest(args);
    okhttp3.Call call = serviceMethod.callFactory.newCall(request);
    if (call == null) {
      throw new NullPointerException("Call.Factory returned null.");
    }
    return call;
  }

在代理类的invoke方法中serviceMethod.callAdapter.adapt(okHttpCall);
默认返回的ExecutorCallbackCall
指定RxJavaCallAdapterFactory返回一个observable,通知方法中requestArbiter请求

CallOnSubscribe(Call originalCall) {
      this.originalCall = originalCall;
    }

    @Override public void call(final Subscriber> subscriber) {
      // Since Call is a one-shot type, clone it for each new subscriber.
      Call call = originalCall.clone();

      // Wrap the call in a helper which handles both unsubscription and backpressure.
      RequestArbiter requestArbiter = new RequestArbiter<>(call, subscriber);
      subscriber.add(requestArbiter);
      subscriber.setProducer(requestArbiter);
    }
  }
//请求
  public void setProducer(Producer p) {
...
producer.request(Long.MAX_VALUE);
...
}
 @Override public void request(long n) {
...
 Response response = call.execute();
...
}