Retrofit源码分析

参考：https://www.jianshu.com/p/064d944606a7

先看下入口：

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 {
        // If the method is a method from Object then defer to normal invocation.
        if (method.getDeclaringClass() == Object.class) {
          return method.invoke(this, args);
        }
        if (platform.isDefaultMethod(method)) {
          return platform.invokeDefaultMethod(method, service, proxy, args);
        }
        ServiceMethod<Object, Object> serviceMethod =
            (ServiceMethod<Object, Object>) loadServiceMethod(method);
        OkHttpCall<Object> okHttpCall = new OkHttpCall<>(serviceMethod, args);
        return serviceMethod.adapt(okHttpCall);
      }
    });

用动态代理生成代理对象，然后Service调用方法时，将方法的参数信息注解类型封装成ServiceMethod：

ServiceMethod<Object, Object> serviceMethod =(ServiceMethod<Object, Object>) loadServiceMethod(method);

然后将方法调用传进来的实参args 和serviceMethod封装成OkHttpCall

OkHttpCall