@Retrofit 解析

解析的原因

我想给Service的每个body加上基本参数，如platform,version等

解析

我发现所有的service经过一个动态代理代理了所有方法，然后解析service方法的参数和返回值（获取参数的方式是通过反射方法的注解得到）。然后把参数作为okhttp的参数执行请求，请求回调中将结果解析成service方法的返回值，再通过rxjava的Observable传递给调用者。

核心代码解析

retrofit核心代码

public <T> T create(final Class<T> service) {
Utils.validateServiceInterface(service);
if (validateEagerly) {
  eagerlyValidateMethods(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 {
        // 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.callAdapter.adapt(okHttpCall);
      }
    });
}

解析结果

我成功的把每个body添加了基本参数
我把body都继承自BaseBody,然后重写GsonRequestBodyConverter

/**
* Created by antelope on 2017/12/6.
*/

public class MyGsonRequestBodyConverter<T> implements Converter<T, RequestBody> {
private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8");
private static final Charset UTF_8 = Charset.forName("UTF-8");

private final Gson gson;
private final TypeAdapter<T> adapter;
private String version;

public MyGsonRequestBodyConverter<T> setVersion(String version) {
    this.version = version;
    return this;
}


public MyGsonRequestBodyConverter(Gson gson, TypeAdapter<T> adapter) {
    this.gson = gson;
    this.adapter = adapter;
}

@Override
public RequestBody convert(T value) throws IOException {
    Buffer buffer = new Buffer();
    Writer writer = new OutputStreamWriter(buffer.outputStream(), UTF_8);
    JsonWriter jsonWriter = gson.newJsonWriter(writer);
    try {
        value.getClass().getMethod("setPlatform", String.class).invoke(value, "01");
        if (version != null) {
            value.getClass().getMethod("setVersion", String.class).invoke(value, version);
        }
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        e.printStackTrace();
    }
    adapter.write(jsonWriter, value);
    jsonWriter.close();
    return RequestBody.create(MEDIA_TYPE, buffer.readByteString());
}
}