Retrofit: 设计模式
适配器模式就是，已经存在的OkHttpCall，要被不同的标准，平台来调用。设计了一个接口CallAdapter，让其他平台都是做不同的实现来转换，这样不花很大的代价就能再兼容一个平台
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();
private final Object[] emptyArgs = new Object[0];
@Override public @Nullable 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);
}
return loadServiceMethod(method).invoke(args != null ? args : emptyArgs);
}
});
}
1,retrofit.create(ApiService.class)采用动态代理模式,即动态实现ApiService接口,动态接收接口中方法
2,获取接口中方法,注解,返回值
3,调用CallAdapterFactory.get(),ConverterFactory.responseBodyConverter(),即执行RxJava2CallAdapterFactory
,ResponseConverterFactory中get和responseBodyConverter
4,得到callAdapter,responseConverter,创建ServiceMethod(CallAdapted)
5,调用ServiceMethod.invoke,即HttpServiceMethod.invoke
6,invoke中创建OkhttpCall,call实现类,执行okhttp请求,parseResponse,调用到ResponseConverterFactory中convert
@Override final @Nullable ReturnT invoke(Object[] args) {
Call<ResponseT> call = new OkHttpCall<>(requestFactory, args, callFactory, responseConverter);
return adapt(call, args);
}
6,调用callAdapter.adapter,实现为RxJava2CallAdapter,返回对应Observer或者Call
static final class CallAdapted<ResponseT, ReturnT> extends HttpServiceMethod<ResponseT, ReturnT> {
private final CallAdapter<ResponseT, ReturnT> callAdapter;
CallAdapted(RequestFactory requestFactory, okhttp3.Call.Factory callFactory,
Converter<ResponseBody, ResponseT> responseConverter,
CallAdapter<ResponseT, ReturnT> callAdapter) {
super(requestFactory, callFactory, responseConverter);
this.callAdapter = callAdapter;
}
@Override protected ReturnT adapt(Call<ResponseT> call, Object[] args) {
return callAdapter.adapt(call);
}
}
