Retrofit核心类分析和调用流程源码分析

基于retrofit2.1.0

核心类介绍
ParameterHandler      解析方法参数的注解获取他们信息,然后调用转换器,然后设置到RequestBuilder
不同的注解有不同的ParameterHandler      实现

Converter    转换器接口,我们自定义一些实现,可以通过它自定义,进行请求参数数据转换,相应参数自定义解析,还有设置数据,把数据转化为String

Converter.Factory 
核心方法:responseBodyConverter                    根据adapter中的ResponseType,类型来解析数据
    requestBodyConverter    Body ,PartMap,Part方法参数中的这三个注解,都是需要把数据,转化为RequestBody类型的
    stringConverter    //把各种类型的数据转化为String,主要用在,对于方法的请求参数,的注解的数据类型进行转换,转换为String,然后设置到RequestBuilder

ServiceMethod:指责很多
        1.获取方法和参数的注解
        2.根据adapter返回值的类型,和根据参数的类型获取就行的Converter.Factory ,创建对应的Converter  
        3.然后解析方法的注解,解析参数的注解(ParameterHandler),很多都要依赖Converter  ,
        4.根据解析的数据,配合ParameterHandler,创建RequestBuilder
        5.创建请求Request
        6.使用responseBodyConverter解析请求
CallAdapter.Factory:根据定义的接口中返回的类型,返回指定的Factory
        可以把Call转化为任意的返回值,让我们以自定义的方式,触发请求,并且可以自定义对相应的统一处理,然后给出自定义的回调。

 

 

方法参数注解概述

Query   设置查询参数,key=value

Path     用来替换相对路径中的值

Url      再参数中设置相对路径

QueryMap    设置多个查询参数,设置一个map子类   ,并且key必须要是String,value的值不限制,但是要负责转化为String

Header  添加请求头

HeaderMap   设置多个请求头,设置一个map子类   ,并且key必须要是String,value的值不限制,但是要负责转化为String

Field     添加表单字段     type 也是可以是任意类型,只要可以转换为String 就可以

FieldMap    添加多个表单字段,key必须为String ,value可以是任意类型

Part             请求Multipart下的一个请求体,和请求头,如果设置了value,就不要使用Okhttp的Part,如果没有设置,就必须要是Okhttp的Part

PartMap      上面的请求的Map形式

Body  直接设置给请求体,需要我们自定义ReuqestBody转换器


上面的注解涵盖了Http请求的各个部分,我们可以通过这些注解标识数据,然后设置他们,并且Retrofit做的非常好的是,只是用注解标识数据再http中的位置,但是注解标识的数据类型,不做限制,可以是任意数据类型,然后我们只要设置对应类型的的数据转换器,就可以了,极大的提高了扩展性,再后面方法参数解析为ParameterHandler的步骤会体现。

 

        
代码流程分析
    Retrofit retrofit = new Retrofit.Builder()
        .baseUrl(NetConfiguration.getInstance().getBaseUrl())//设置BaseUrl
        .addConverterFactory(GsonConverterFactory.create(gson))//添加转换器工厂
        .addCallAdapterFactory(new ExecutorCallAdapterFactory1())//添加CallAdapter工厂
        .client(getGenericClient())//设置CallFactory
        .callbackExecutor(null)//设置CallBack执行的线程,可以再主线程或者子线程,再测试的时候很有用
        .build();
->构建Retrofit   
-》retrofit.create(clazz);
  public T create(final Class service) {
    Utils.validateServiceInterface(service);                   //检查接口是否合法,不能有继承接口
    if (validateEagerly) {//是否提前解析每一个方法,默认是false,可以再构建的时候设置,会占用内存,但是会提高执行请求的效率
      eagerlyValidateMethods(service);                       //会在内部把Method解析成ServiceMethod
    }
    return (T) Proxy.newProxyInstance(service.getClassLoader(), new Class[] { service },               //为接口生成动态代理类
        new InvocationHandler() {
          private final Platform platform = Platform.get();

          @Override public Object invoke(Object proxy, Method method, Object... args)
              throws Throwable {
            // If the method is a method from Object then defer to normal invocation.
            if (method.getDeclaringClass() == Object.class) {           //如果类是Object定义的,就原样执行
              return method.invoke(this, args);
            }
            if (platform.isDefaultMethod(method)) {//根据平台特性判断,如果是默认方法,就调用对应平台的执行方式
              return platform.invokeDefaultMethod(method, service, proxy, args);
            }
            ServiceMethod serviceMethod = loadServiceMethod(method);//根据Method信息构建ServiceMethod ,核心类,一会具体分析
            OkHttpCall okHttpCall = new OkHttpCall<>(serviceMethod, args);//实现Call,内部会使用serviceMethod,来生成request,并且解析相应
            return serviceMethod.callAdapter.adapt(okHttpCall);//调用callAdapter,再适配返回值类型,返回执行类型
          }
        });
  }
分析个对象的构建
-》  ServiceMethod serviceMethod = loadServiceMethod(method);
ServiceMethod loadServiceMethod(Method method) {
    ServiceMethod result;
    synchronized (serviceMethodCache) {
      result = serviceMethodCache.get(method);//从缓存中获取,缓存可以太高效率
      if (result == null) {
        result = new ServiceMethod.Builder(this, method).build();//如果没有重新构建
        serviceMethodCache.put(method, result);//并且放入缓存
      }
    }
    return result;
  }
-》 new ServiceMethod.Builder(this, method).build();
-》 new ServiceMethod.Builder(this, method)
    public Builder(Retrofit retrofit, Method method) {
      this.retrofit = retrofit;
      this.method = method;
      this.methodAnnotations = method.getAnnotations();//获取方法的注解
      this.parameterTypes = method.getGenericParameterTypes();//获取方法参数数组
      this.parameterAnnotationsArray = method.getParameterAnnotations();//获取方法参数对应位置的注解,二维数组
    }
-》  public ServiceMethod build()
    public ServiceMethod build() {
      callAdapter = createCallAdapter();//根据接口中定义的返回值类型,从Factory中寻找合适的CallAdapter
      responseType = callAdapter.responseType();//CallAdapter,返回,按照这个类型来解析http的相应
      if (responseType == Response.class || responseType == okhttp3.Response.class) {
        throw methodError("'"
            + Utils.getRawType(responseType).getName()
            + "' is not a valid response body type. Did you mean ResponseBody?");
      }
      responseConverter = createResponseConverter();//根据responseType 返回解析ResponBody的responseConverter

      for (Annotation annotation : methodAnnotations) {//遍历方法的注解,然后解析方法的注解,参数保存到Builder
        parseMethodAnnotation(annotation);//解析方法注解
      }

      if (httpMethod == null) {
        throw methodError("HTTP method annotation is required (e.g., @GET, @POST, etc.).");
      }

      if (!hasBody) {
        if (isMultipart) {
          throw methodError(
              "Multipart can only be specified on HTTP methods with request body (e.g., @POST).");
        }
        if (isFormEncoded) {
          throw methodError("FormUrlEncoded can only be specified on HTTP methods with "
              + "request body (e.g., @POST).");
        }
      }

      int parameterCount = parameterAnnotationsArray.length;
      parameterHandlers = new ParameterHandler[parameterCount];//每一个 parameterHandler负责设置对应注解的相关类型到RequestBuiler,保存了所有的参数的设置器
      for (int p = 0; p < parameterCount; p++) {
        Type parameterType = parameterTypes[p];
        if (Utils.hasUnresolvableType(parameterType)) {
          throw parameterError(p, "Parameter type must not include a type variable or wildcard: %s",
              parameterType);
        }

        Annotation[] parameterAnnotations = parameterAnnotationsArray[p];
        if (parameterAnnotations == null) {
          throw parameterError(p, "No Retrofit annotation found.");
        }

        parameterHandlers[p] = parseParameter(p, parameterType, parameterAnnotations);//感觉注解类型生成对应的参数设置器
      }

      if (relativeUrl == null && !gotUrl) {
        throw methodError("Missing either @%s URL or @Url parameter.", httpMethod);
      }
      if (!isFormEncoded && !isMultipart && !hasBody && gotBody) {
        throw methodError("Non-body HTTP method cannot contain @Body.");
      }
      if (isFormEncoded && !gotField) {
        throw methodError("Form-encoded method must contain at least one @Field.");
      }
      if (isMultipart && !gotPart) {
        throw methodError("Multipart method must contain at least one @Part.");
      }

      return new ServiceMethod<>(this);//把解析的参数设置到ServiceMethod
    }

-》 createCallAdapter();
  private CallAdapter createCallAdapter() {
      Type returnType = method.getGenericReturnType();
      if (Utils.hasUnresolvableType(returnType)) {
        throw methodError(
            "Method return type must not include a type variable or wildcard: %s", returnType);
      }
      if (returnType == void.class) {
        throw methodError("Service methods cannot return void.");
      }
      Annotation[] annotations = method.getAnnotations();
      try {
        return retrofit.callAdapter(returnType, annotations);//根据返回值类型,返回CallAdapter
      } catch (RuntimeException e) { // Wide exception range because factories are user code.
        throw methodError(e, "Unable to create call adapter for %s", returnType);
      }
    }
-》 createResponseConverter();
    private Converter createResponseConverter() {
      Annotation[] annotations = method.getAnnotations();
      try {
        return retrofit.responseBodyConverter(responseType, annotations);//根据返回值类型创建这个返回执行的,相应解析器
      } catch (RuntimeException e) { // Wide exception range because factories are user code.
        throw methodError(e, "Unable to create converter for %s", responseType);
      }
    }

-》parseMethodAnnotation(Annotation annotation)
 private void parseMethodAnnotation(Annotation annotation) {//根绝注解类型,解析方法上的注解
      if (annotation instanceof DELETE) {
        parseHttpMethodAndPath("DELETE", ((DELETE) annotation).value(), false);
      } else if (annotation instanceof GET) {
        parseHttpMethodAndPath("GET", ((GET) annotation).value(), false);
      } else if (annotation instanceof HEAD) {
        parseHttpMethodAndPath("HEAD", ((HEAD) annotation).value(), false);
        if (!Void.class.equals(responseType)) {
          throw methodError("HEAD method must use Void as response type.");
        }
      } else if (annotation instanceof PATCH) {
        parseHttpMethodAndPath("PATCH", ((PATCH) annotation).value(), true);
      } else if (annotation instanceof POST) {
        parseHttpMethodAndPath("POST", ((POST) annotation).value(), true);
      } else if (annotation instanceof PUT) {
        parseHttpMethodAndPath("PUT", ((PUT) annotation).value(), true);
      } else if (annotation instanceof OPTIONS) {
        parseHttpMethodAndPath("OPTIONS", ((OPTIONS) annotation).value(), false);
      } else if (annotation instanceof HTTP) {
        HTTP http = (HTTP) annotation;
        parseHttpMethodAndPath(http.method(), http.path(), http.hasBody());
      } else if (annotation instanceof retrofit2.http.Headers) {
        String[] headersToParse = ((retrofit2.http.Headers) annotation).value();
        if (headersToParse.length == 0) {
          throw methodError("@Headers annotation is empty.");
        }
        headers = parseHeaders(headersToParse);
      } else if (annotation instanceof Multipart) {
        if (isFormEncoded) {
          throw methodError("Only one encoding annotation is allowed.");
        }
        isMultipart = true;
      } else if (annotation instanceof FormUrlEncoded) {
        if (isMultipart) {
          throw methodError("Only one encoding annotation is allowed.");
        }
        isFormEncoded = true;
      }
    }
-》parseHttpMethodAndPath(String httpMethod, String value, boolean hasBody)//设置解析的请求方法,并且设置相对url
private void parseHttpMethodAndPath(String httpMethod, String value, boolean hasBody) {
      if (this.httpMethod != null) {
        throw methodError("Only one HTTP method is allowed. Found: %s and %s.",
            this.httpMethod, httpMethod);
      }
      this.httpMethod = httpMethod;
      this.hasBody = hasBody;

      if (value.isEmpty()) {
        return;
      }

      // Get the relative URL path and existing query string, if present.
      int question = value.indexOf('?');
      if (question != -1 && question < value.length() - 1) {
        // Ensure the query string does not have any named parameters.
        String queryParams = value.substring(question + 1);
        Matcher queryParamMatcher = PARAM_URL_REGEX.matcher(queryParams);
        if (queryParamMatcher.find()) {
          throw methodError("URL query string \"%s\" must not have replace block. "
              + "For dynamic query parameters use @Query.", queryParams);
        }
      }

      this.relativeUrl = value;
      this.relativeUrlParamNames = parsePathParameters(value);
    }
-》        parameterHandlers[p] = parseParameter(p, parameterType, parameterAnnotations);
 private ParameterHandler parseParameter(
        int p, Type parameterType, Annotation[] annotations) {
      ParameterHandler result = null;
      for (Annotation annotation : annotations) {//遍历方法的参数和注解,然后解析出对应的参数设置器
        ParameterHandler annotationAction = parseParameterAnnotation(
            p, parameterType, annotations, annotation);//根据注解,解析出对应的参数设置器

        if (annotationAction == null) {
          continue;
        }

        if (result != null) {
          throw parameterError(p, "Multiple Retrofit annotations found, only one allowed.");
        }

        result = annotationAction;
      }

      if (result == null) {
        throw parameterError(p, "No Retrofit annotation found.");
      }

      return result;
    }
-》 parseParameterAnnotation(
            p, parameterType, annotations, annotation);//各注解解析类似,我们只分析一个
 private ParameterHandler parseParameterAnnotation(
        int p, Type type, Annotation[] annotations, Annotation annotation) {
      if (annotation instanceof Url) {
        if (gotUrl) {
          throw parameterError(p, "Multiple @Url method annotations found.");
        }
        if (gotPath) {
          throw parameterError(p, "@Path parameters may not be used with @Url.");
        }
        if (gotQuery) {
          throw parameterError(p, "A @Url parameter must not come after a @Query");
        }
        if (relativeUrl != null) {
          throw parameterError(p, "@Url cannot be used with @%s URL", httpMethod);
        }

        gotUrl = true;

        if (type == HttpUrl.class
            || type == String.class
            || type == URI.class
            || (type instanceof Class && "android.net.Uri".equals(((Class) type).getName()))) {
          return new ParameterHandler.RelativeUrl();
        } else {
          throw parameterError(p,
              "@Url must be okhttp3.HttpUrl, String, java.net.URI, or android.net.Uri type.");
        }

      } else if (annotation instanceof Path) {
        if (gotQuery) {
          throw parameterError(p, "A @Path parameter must not come after a @Query.");
        }
        if (gotUrl) {
          throw parameterError(p, "@Path parameters may not be used with @Url.");
        }
        if (relativeUrl == null) {
          throw parameterError(p, "@Path can only be used with relative url on @%s", httpMethod);
        }
        gotPath = true;

        Path path = (Path) annotation;
        String name = path.value();
        validatePathName(p, name);

        Converter converter = retrofit.stringConverter(type, annotations);
        return new ParameterHandler.Path<>(name, converter, path.encoded());

      } else if (annotation instanceof Query) {
        Query query = (Query) annotation;//获取注解
        String name = query.value();//返回注解的值
        boolean encoded = query.encoded();//是否需要url编码

        Class rawParameterType = Utils.getRawType(type);//获取主类型
        gotQuery = true;
        if (Iterable.class.isAssignableFrom(rawParameterType)) {//判断是否传递的是一个迭代器类型
          if (!(type instanceof ParameterizedType)) {//如果传递了迭代器类型,就一定要传递泛型的具体类型,否则报错,因为要设置数据,所以必须要是具体类型
            throw parameterError(p, rawParameterType.getSimpleName()
                + " must include generic type (e.g., "
                + rawParameterType.getSimpleName()
                + ")");
          }
          ParameterizedType parameterizedType = (ParameterizedType) type;
          Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
          Converter converter =
              retrofit.stringConverter(iterableType, annotations);//对迭代器中的类型,调用stringConvert转化为String类型
          return new ParameterHandler.Query<>(name, converter, encoded).iterable();//内部会迭代执行,把数据设置到RequestBuilder
        } else if (rawParameterType.isArray()) {
          Class arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
          Converter converter =
              retrofit.stringConverter(arrayComponentType, annotations);
          return new ParameterHandler.Query<>(name, converter, encoded).array();
        } else {
          Converter converter =
              retrofit.stringConverter(type, annotations);
          return new ParameterHandler.Query<>(name, converter, encoded);
        }

      } else if (annotation instanceof QueryMap) {
        Class rawParameterType = Utils.getRawType(type);
        if (!Map.class.isAssignableFrom(rawParameterType)) {
          throw parameterError(p, "@QueryMap parameter type must be Map.");
        }
        Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
        if (!(mapType instanceof ParameterizedType)) {
          throw parameterError(p, "Map must include generic types (e.g., Map)");
        }
        ParameterizedType parameterizedType = (ParameterizedType) mapType;
        Type keyType = Utils.getParameterUpperBound(0, parameterizedType);
        if (String.class != keyType) {
          throw parameterError(p, "@QueryMap keys must be of type String: " + keyType);
        }
        Type valueType = Utils.getParameterUpperBound(1, parameterizedType);
        Converter valueConverter =
            retrofit.stringConverter(valueType, annotations);

        return new ParameterHandler.QueryMap<>(valueConverter, ((QueryMap) annotation).encoded());

      } else if (annotation instanceof Header) {
        Header header = (Header) annotation;
        String name = header.value();

        Class rawParameterType = Utils.getRawType(type);
        if (Iterable.class.isAssignableFrom(rawParameterType)) {
          if (!(type instanceof ParameterizedType)) {
            throw parameterError(p, rawParameterType.getSimpleName()
                + " must include generic type (e.g., "
                + rawParameterType.getSimpleName()
                + ")");
          }
          ParameterizedType parameterizedType = (ParameterizedType) type;
          Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
          Converter converter =
              retrofit.stringConverter(iterableType, annotations);
          return new ParameterHandler.Header<>(name, converter).iterable();
        } else if (rawParameterType.isArray()) {
          Class arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
          Converter converter =
              retrofit.stringConverter(arrayComponentType, annotations);
          return new ParameterHandler.Header<>(name, converter).array();
        } else {
          Converter converter =
              retrofit.stringConverter(type, annotations);
          return new ParameterHandler.Header<>(name, converter);
        }

      } else if (annotation instanceof HeaderMap) {
        Class rawParameterType = Utils.getRawType(type);
        if (!Map.class.isAssignableFrom(rawParameterType)) {
          throw parameterError(p, "@HeaderMap parameter type must be Map.");
        }
        Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
        if (!(mapType instanceof ParameterizedType)) {
          throw parameterError(p, "Map must include generic types (e.g., Map)");
        }
        ParameterizedType parameterizedType = (ParameterizedType) mapType;
        Type keyType = Utils.getParameterUpperBound(0, parameterizedType);
        if (String.class != keyType) {
          throw parameterError(p, "@HeaderMap keys must be of type String: " + keyType);
        }
        Type valueType = Utils.getParameterUpperBound(1, parameterizedType);
        Converter valueConverter =
            retrofit.stringConverter(valueType, annotations);

        return new ParameterHandler.HeaderMap<>(valueConverter);

      } else if (annotation instanceof Field) {
        if (!isFormEncoded) {
          throw parameterError(p, "@Field parameters can only be used with form encoding.");
        }
        Field field = (Field) annotation;
        String name = field.value();
        boolean encoded = field.encoded();

        gotField = true;

        Class rawParameterType = Utils.getRawType(type);
        if (Iterable.class.isAssignableFrom(rawParameterType)) {
          if (!(type instanceof ParameterizedType)) {
            throw parameterError(p, rawParameterType.getSimpleName()
                + " must include generic type (e.g., "
                + rawParameterType.getSimpleName()
                + ")");
          }
          ParameterizedType parameterizedType = (ParameterizedType) type;
          Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
          Converter converter =
              retrofit.stringConverter(iterableType, annotations);
          return new ParameterHandler.Field<>(name, converter, encoded).iterable();
        } else if (rawParameterType.isArray()) {
          Class arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
          Converter converter =
              retrofit.stringConverter(arrayComponentType, annotations);
          return new ParameterHandler.Field<>(name, converter, encoded).array();
        } else {
          Converter converter =
              retrofit.stringConverter(type, annotations);
          return new ParameterHandler.Field<>(name, converter, encoded);
        }

      } else if (annotation instanceof FieldMap) {
        if (!isFormEncoded) {
          throw parameterError(p, "@FieldMap parameters can only be used with form encoding.");
        }
        Class rawParameterType = Utils.getRawType(type);
        if (!Map.class.isAssignableFrom(rawParameterType)) {
          throw parameterError(p, "@FieldMap parameter type must be Map.");
        }
        Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
        if (!(mapType instanceof ParameterizedType)) {
          throw parameterError(p,
              "Map must include generic types (e.g., Map)");
        }
        ParameterizedType parameterizedType = (ParameterizedType) mapType;
        Type keyType = Utils.getParameterUpperBound(0, parameterizedType);
        if (String.class != keyType) {
          throw parameterError(p, "@FieldMap keys must be of type String: " + keyType);
        }
        Type valueType = Utils.getParameterUpperBound(1, parameterizedType);
        Converter valueConverter =
            retrofit.stringConverter(valueType, annotations);

        gotField = true;
        return new ParameterHandler.FieldMap<>(valueConverter, ((FieldMap) annotation).encoded());

      } else if (annotation instanceof Part) {
        if (!isMultipart) {
          throw parameterError(p, "@Part parameters can only be used with multipart encoding.");
        }
        Part part = (Part) annotation;
        gotPart = true;

        String partName = part.value();
        Class rawParameterType = Utils.getRawType(type);
        if (partName.isEmpty()) {
          if (Iterable.class.isAssignableFrom(rawParameterType)) {
            if (!(type instanceof ParameterizedType)) {
              throw parameterError(p, rawParameterType.getSimpleName()
                  + " must include generic type (e.g., "
                  + rawParameterType.getSimpleName()
                  + ")");
            }
            ParameterizedType parameterizedType = (ParameterizedType) type;
            Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
            if (!MultipartBody.Part.class.isAssignableFrom(Utils.getRawType(iterableType))) {
              throw parameterError(p,
                  "@Part annotation must supply a name or use MultipartBody.Part parameter type.");
            }
            return ParameterHandler.RawPart.INSTANCE.iterable();
          } else if (rawParameterType.isArray()) {
            Class arrayComponentType = rawParameterType.getComponentType();
            if (!MultipartBody.Part.class.isAssignableFrom(arrayComponentType)) {
              throw parameterError(p,
                  "@Part annotation must supply a name or use MultipartBody.Part parameter type.");
            }
            return ParameterHandler.RawPart.INSTANCE.array();
          } else if (MultipartBody.Part.class.isAssignableFrom(rawParameterType)) {
            return ParameterHandler.RawPart.INSTANCE;
          } else {
            throw parameterError(p,
                "@Part annotation must supply a name or use MultipartBody.Part parameter type.");
          }
        } else {
          Headers headers =
              Headers.of("Content-Disposition", "form-data; name=\"" + partName + "\"",
                  "Content-Transfer-Encoding", part.encoding());

          if (Iterable.class.isAssignableFrom(rawParameterType)) {
            if (!(type instanceof ParameterizedType)) {
              throw parameterError(p, rawParameterType.getSimpleName()
                  + " must include generic type (e.g., "
                  + rawParameterType.getSimpleName()
                  + ")");
            }
            ParameterizedType parameterizedType = (ParameterizedType) type;
            Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
            if (MultipartBody.Part.class.isAssignableFrom(Utils.getRawType(iterableType))) {
              throw parameterError(p, "@Part parameters using the MultipartBody.Part must not "
                  + "include a part name in the annotation.");
            }
            Converter converter =
                retrofit.requestBodyConverter(iterableType, annotations, methodAnnotations);
            return new ParameterHandler.Part<>(headers, converter).iterable();
          } else if (rawParameterType.isArray()) {
            Class arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
            if (MultipartBody.Part.class.isAssignableFrom(arrayComponentType)) {
              throw parameterError(p, "@Part parameters using the MultipartBody.Part must not "
                  + "include a part name in the annotation.");
            }
            Converter converter =
                retrofit.requestBodyConverter(arrayComponentType, annotations, methodAnnotations);
            return new ParameterHandler.Part<>(headers, converter).array();
          } else if (MultipartBody.Part.class.isAssignableFrom(rawParameterType)) {
            throw parameterError(p, "@Part parameters using the MultipartBody.Part must not "
                + "include a part name in the annotation.");
          } else {
            Converter converter =
                retrofit.requestBodyConverter(type, annotations, methodAnnotations);
            return new ParameterHandler.Part<>(headers, converter);
          }
        }

      } else if (annotation instanceof PartMap) {
        if (!isMultipart) {
          throw parameterError(p, "@PartMap parameters can only be used with multipart encoding.");
        }
        gotPart = true;
        Class rawParameterType = Utils.getRawType(type);
        if (!Map.class.isAssignableFrom(rawParameterType)) {
          throw parameterError(p, "@PartMap parameter type must be Map.");
        }
        Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
        if (!(mapType instanceof ParameterizedType)) {
          throw parameterError(p, "Map must include generic types (e.g., Map)");
        }
        ParameterizedType parameterizedType = (ParameterizedType) mapType;

        Type keyType = Utils.getParameterUpperBound(0, parameterizedType);
        if (String.class != keyType) {
          throw parameterError(p, "@PartMap keys must be of type String: " + keyType);
        }

        Type valueType = Utils.getParameterUpperBound(1, parameterizedType);
        if (MultipartBody.Part.class.isAssignableFrom(Utils.getRawType(valueType))) {
          throw parameterError(p, "@PartMap values cannot be MultipartBody.Part. "
              + "Use @Part List or a different value type instead.");
        }

        Converter valueConverter =
            retrofit.requestBodyConverter(valueType, annotations, methodAnnotations);

        PartMap partMap = (PartMap) annotation;
        return new ParameterHandler.PartMap<>(valueConverter, partMap.encoding());

      } else if (annotation instanceof Body) {
        if (isFormEncoded || isMultipart) {
          throw parameterError(p,
              "@Body parameters cannot be used with form or multi-part encoding.");
        }
        if (gotBody) {
          throw parameterError(p, "Multiple @Body method annotations found.");
        }

        Converter converter;
        try {
          converter = retrofit.requestBodyConverter(type, annotations, methodAnnotations);
        } catch (RuntimeException e) {
          // Wide exception range because factories are user code.
          throw parameterError(e, p, "Unable to create @Body converter for %s", type);
        }
        gotBody = true;
        return new ParameterHandler.Body<>(converter);
      }

      return null; // Not a Retrofit annotation.
    }


现在数据已经准备好了,开始执行,执行是由请求接口中返回的数据来触发的,虽然返回的类型多种多样
但是,最终内部触发请求,就是调用Retrifit 的OkHttpCall(实现了Call接口)的方法
分析异步请求
OkHttpCall.enqueue(final Callback callback)
  @Override public void enqueue(final Callback callback) {
    if (callback == null) throw new NullPointerException("callback == null");

    okhttp3.Call call;
    Throwable failure;

    synchronized (this) {
      if (executed) throw new IllegalStateException("Already executed.");
      executed = true;

      call = rawCall;
      failure = creationFailure;
      if (call == null && failure == null) {
        try {
          call = rawCall = createRawCall();//创建Call,创建的是Okhttp的Call
        } catch (Throwable t) {
          failure = creationFailure = t;//创建失败
        }
      }
    }

    if (failure != null) {
      callback.onFailure(this, failure);//创建失败直接走失败回调
      return;
    }

    if (canceled) {
      call.cancel();//如果调用了取消请求,就取消请求
    }

    call.enqueue(new okhttp3.Callback() {
      @Override public void onResponse(okhttp3.Call call, okhttp3.Response rawResponse)
          throws IOException {
        Response response;
        try {
          response = parseResponse(rawResponse);//解析响应
        } catch (Throwable e) {
          callFailure(e);
          return;
        }
        callSuccess(response);//解析成功,走成功回调
      }

      @Override public void onFailure(okhttp3.Call call, IOException e) {
        try {
          callback.onFailure(OkHttpCall.this, e);//走失败回调
        } catch (Throwable t) {
          t.printStackTrace();
        }
      }

      private void callFailure(Throwable e) {
        try {
          callback.onFailure(OkHttpCall.this, e);
        } catch (Throwable t) {
          t.printStackTrace();
        }
      }

      private void callSuccess(Response response) {
        try {
          callback.onResponse(OkHttpCall.this, response);
        } catch (Throwable t) {
          t.printStackTrace();
        }
      }
    });
  }
-》  call = rawCall = createRawCall();//创建Call,创建的是Okhttp的Call
  private okhttp3.Call createRawCall() throws IOException {
    Request request = serviceMethod.toRequest(args);//调用serviceMethod.toRequest(方法参数)创建请求
    okhttp3.Call call = serviceMethod.callFactory.newCall(request);//根据请求,调用CallFactory(创建Retrifit的时候设置),生成一个Okhttp的Call
    if (call == null) {
      throw new NullPointerException("Call.Factory returned null.");
    }
    return call;//返回Call
  }
->Request request = serviceMethod.toRequest(args);//调用serviceMethod.toRequest(方法参数)创建请求
 Request toRequest(Object... args) throws IOException {
    RequestBuilder requestBuilder = new RequestBuilder(httpMethod, baseUrl, relativeUrl, headers,
        contentType, hasBody, isFormEncoded, isMultipart);//根据已经解析的一些基本信息,创建RequestBuilder

    @SuppressWarnings("unchecked") // It is an error to invoke a method with the wrong arg types.
    ParameterHandler[] handlers = (ParameterHandler[]) parameterHandlers;//这里是根据参数解析成的请求参数设置器

    int argumentCount = args != null ? args.length : 0;
    if (argumentCount != handlers.length) {
      throw new IllegalArgumentException("Argument count (" + argumentCount
          + ") doesn't match expected count (" + handlers.length + ")");
    }

    for (int p = 0; p < argumentCount; p++) {
      handlers[p].apply(requestBuilder, args[p]);//遍历执行请求参数设置器,让设置器把数据设置到,RequestBuilder
    }

    return requestBuilder.build();//生成请求
  }
-》     response = parseResponse(rawResponse);//解析响应

Response parseResponse(okhttp3.Response rawResponse) throws IOException {
    ResponseBody rawBody = rawResponse.body();

    // Remove the body's source (the only stateful object) so we can pass the response along.
    rawResponse = rawResponse.newBuilder()
        .body(new NoContentResponseBody(rawBody.contentType(), rawBody.contentLength()))
        .build();

    int code = rawResponse.code();
    if (code < 200 || code >= 300) {
      try {
        // Buffer the entire body to avoid future I/O.
        ResponseBody bufferedBody = Utils.buffer(rawBody);
        return Response.error(bufferedBody, rawResponse);
      } finally {
        rawBody.close();
      }
    }

    if (code == 204 || code == 205) {
      return Response.success(null, rawResponse);
    }

    ExceptionCatchingRequestBody catchingBody = new ExceptionCatchingRequestBody(rawBody);
    try {
      T body = serviceMethod.toResponse(catchingBody);//调用serviceMethod.toResponse(catchingBody);转换响应
      return Response.success(body, rawResponse);//返回成功响应
    } catch (RuntimeException e) {
      // If the underlying source threw an exception, propagate that rather than indicating it was
      // a runtime exception.
      catchingBody.throwIfCaught();
      throw e;
    }
  }
-》serviceMethod.toResponse(catchingBody);转换响应
  T toResponse(ResponseBody body) throws IOException {
    return responseConverter.convert(body);//调用之前根据adapter返回的responseType获取的ResponeConvert
  }

-》返回到最初的create方法,动态代理中
         OkHttpCall okHttpCall = new OkHttpCall<>(serviceMethod, args);
            return serviceMethod.callAdapter.adapt(okHttpCall);//会从 serviceMethod中获取根据接口方法返回值类型解析得到的CallAdapter


调用结束。

扩展使用,根据动态代理的思想,我们可以再接口方法上自定义我们自己的注解,然后是动态代理的时候,我们自己再包一层然后设置一些自己的参数。

 

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