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Swift-Moya 源码解析

Swift-Moya 源码解析

作者: iOS_磊 | 来源:发表于2020-12-03 13:39 被阅读0次

    1.Moya的定义

    • Moya是一个高度抽象的网络库，他的理念是让你不用关心网络请求的底层的实现细节，只用定义你关心的业务。且Moya采用桥接和组合来进行封装(默认桥接了Alamofire)，使得Moya非常好扩展，让你不用修改Moya源码就可以轻易定制。官方给出几个Moya主要优点:
      • 编译时检查API endpoint权限
      • 让你使用枚举定义各种不同Target, endpoints
      • 把stubs当做一等公民对待，因此测试超级简单。

    2.Moya的使用

    • Moya的使用分成几步，首先需要先自定义一个枚举类型。
    enum SHChannelViewModelApiManager{
    case getChannelList(Bool)
    case getItemList(String)

}
    • 然后遵循开闭原则，让枚举的分类遵循Moya的TargetType,按需实现定义的各种get方法
    public protocol TargetType {

    /// The target's base `URL`.
    var baseURL: URL { get }

    /// The path to be appended to `baseURL` to form the full `URL`.
    var path: String { get }

    /// The HTTP method used in the request.
    var method: Moya.Method { get }

    /// Provides stub data for use in testing.
    var sampleData: Data { get }

    /// The type of HTTP task to be performed.
    var task: Task { get }

    /// A Boolean value determining whether the embedded target performs Alamofire validation. Defaults to `false`.
    var validate: Bool { get }

    /// The headers to be used in the request.
    var headers: [String: String]? { get }
}

    extension  SHChannelViewModelApiManager:TargetType {
   var baseURL: URL {
        return URL(string: baseUrl)!
    }
    var task: Task {
        switch self {
        case .getChannelList:
            return .requestPlain
        case .getItemList(let pipe):
            return .requestParameters(parameters: ["pipe":pipe], encoding: URLEncoding.queryString)
        }
    }
    var method: Moya.Method {
        return .get
    }
    var path: String {
        switch self {
        case .getChannelList(let isToday):
            if isToday{
               return "/Youmeng/chaxunservletall"
            }else{
              return "/Youmeng/chaxunservletallhistory"
            }
        case .getItemList:
            return itemListUrl

        }

    }
}
    • 最后创建MoyaProvider对象,泛型允许传入任何你定义的遵循TargetType协议的枚举，
        let provider = MoyaProvider<SHChannelViewModelApiManager>()
    • 使用MoyaProvider对象发起请求
        provider.rx.request(.getItemList(pipe)).mapArr([SHChannelItemTopModel].self).subscribe(onSuccess: { [weak self](model) in
        self?.topModels = model
        self?.itemOutput.onNext(true)
        }) { [weak self](error) in
            self?.itemOutput.onNext(false)
            }.disposed(by: bag)
    }

    3.Moya的所有文件解析

    • Provider

    • TargetType

      • TargetType

      • MultiTarget (MultiTarget用于使MoyaProvider能够处理多个TargetType）

    • Result

      • Response

      • MoyaError （是一个枚举，定义了 Moya可能抛出的各种错误,包括上面说的 Response三个map方法出错，状态码出错，解码出错，和参数编码错误等，同时有两个get方法，得出错误的Response返回以及错误描述返回)

    • Plugins

    • Alamofire
      这里有一个iOS交流圈：891 488 181 分享BAT,阿里面试题、面试经验，讨论技术， 感兴趣的话大家一起交流学习！

      • Moya+Alamofire (Moya和Alamofire的桥接文件，桥接模式保证了最少知道原则，如果进行替换Alamofire,主要修改这个文件)
      • MultipartFormData (多文件上传与Alamofire的桥接，通过 append等方法把moya形式的MultipartFormData添加到Alamofire里去)

    • URL

      • URL+Moya(通过获取TargetType的baseURL和path初始化一个URL)

      • URLRequest+Encoding(对URLRequest的两个encoded方法)

    3.1.MoyaProvider

    MoyaProvider 初始化

    MoyaProvider是请求提供者类。只能通过该类发起请求,类的初始化如下

        public init(endpointClosure: @escaping EndpointClosure = MoyaProvider.defaultEndpointMapping,
                requestClosure: @escaping RequestClosure = MoyaProvider.defaultRequestMapping,
                stubClosure: @escaping StubClosure = MoyaProvider.neverStub,
                callbackQueue: DispatchQueue? = nil,
                manager: Manager = MoyaProvider<Target>.defaultAlamofireManager(),
                plugins: [PluginType] = [],
                trackInflights: Bool = false) {

        self.endpointClosure = endpointClosure
        self.requestClosure = requestClosure
        self.stubClosure = stubClosure
        self.manager = manager
        self.plugins = plugins
        self.trackInflights = trackInflights
        self.callbackQueue = callbackQueue
    }

    由以上代码可以得知，初始化可传入的参数。

    • EndpointClosure是一个把传入的Target转化为Endpoint对象的闭包，

          public typealias EndpointClosure = (Target) -> Endpoint<Target>

      既然如此，我们就顺腾摸瓜，看一下Endpoint对象里面是什么

      open class Endpoint<Target> {
 public typealias SampleResponseClosure = () -> EndpointSampleResponse

 /// 请求的URL的字符串.
 open let url: String

 /// stub数据的 response(测试用的)
 open let sampleResponseClosure: SampleResponseClosure

 /// 请求方式.
 open let method: Moya.Method

 /// 请求任务.
 open let task: Task

 /// 请求头.
 open let httpHeaderFields: [String: String]?

 public init(url: String,
             sampleResponseClosure: @escaping SampleResponseClosure,
             method: Moya.Method,
             task: Task,
             httpHeaderFields: [String: String]?) {

     self.url = url
     self.sampleResponseClosure = sampleResponseClosure
     self.method = method
     self.task = task
     self.httpHeaderFields = httpHeaderFields
 }
 ...
}

      可以看出，Endpoint的属性，基本对应TargetType协议对应的get方法，所以才能进行转化，EndpointClosure的作用在于，可以根据业务需求在这里重新定制网络请求，还可以通过 stub进行数据测试，可以看看官方默认的闭包实现

       public final class func defaultEndpointMapping(for target: Target) -> Endpoint<Target> {
     return Endpoint(
         url: URL(target: target).absoluteString,
         sampleResponseClosure: { .networkResponse(200, target.sampleData) },
         method: target.method,
         task: target.task,
         httpHeaderFields: target.headers
     )
 }

    • RequestClosure这个闭包实现就是将Endpoint转化成真正的请求对象URLRequest

      //RequestClosure
    public typealias RequestClosure = (Endpoint<Target>, @escaping RequestResultClosure) -> Void
 // 上面的RequestResultClosure
     public typealias RequestResultClosure = (Result<URLRequest, MoyaError>) -> Void

      看看Moya提供的默认实现

          public final class func defaultRequestMapping(for endpoint: Endpoint<Target>, closure: RequestResultClosure) {
     do {
        //urlRequest请求
         let urlRequest = try endpoint.urlRequest()
         closure(.success(urlRequest))
         // MoyaError类型的错误，稍后讲解
     } catch MoyaError.requestMapping(let url) {
         closure(.failure(MoyaError.requestMapping(url)))
     } catch MoyaError.parameterEncoding(let error) {
         closure(.failure(MoyaError.parameterEncoding(error)))
     } catch {
         closure(.failure(MoyaError.underlying(error, nil)))
     }
 }

      上面代码通过endpoint.urlRequest()获得urlRequest，那我们就看一下urlRequest()的具体实现

       public func urlRequest() throws -> URLRequest {
     guard let requestURL = Foundation.URL(string: url) else {
         throw MoyaError.requestMapping(url)
     }

     var request = URLRequest(url: requestURL)
     request.httpMethod = method.rawValue
     request.allHTTPHeaderFields = httpHeaderFields

     switch task {
     case .requestPlain, .uploadFile, .uploadMultipart, .downloadDestination:
         return request
     case .requestData(let data):
         request.httpBody = data
         return request
 //.................此处省略一点代码
     }
 }

      现在我们清晰的发现确实是转成URLRequest了，事实上，这也是Moya给你最后的机会了，举个例子，你想设置超时时间，

      let  requestClosure = { (endpoint:Endpoint<SHChannelViewModelApiManager>,closure:RequestResultClosure){
  do {
         var urlRequest = try endpoint.urlRequest()
         //设置超时时间，urlRequest的可配置的东西都可以在这配置
         urlRequest.timeoutInterval = 60
         closure(.success(urlRequest))
     } catch MoyaError.requestMapping(let url) {
         closure(.failure(MoyaError.requestMapping(url)))
     } catch MoyaError.parameterEncoding(let error) {
         closure(.failure(MoyaError.parameterEncoding(error)))
     } catch {
         closure(.failure(MoyaError.underlying(error, nil)))
     }
}
}

    • StubClosure返回了一个StubBehavior的枚举值,它就是让你告诉Moya你是否使用Stub返回数据或者怎样使用Stub返回数据,默认是不返回

       public typealias StubClosure = (Target) -> Moya.StubBehavior


      public enum StubBehavior {

 /// 不使用Stub返回数据.
 case never

 /// 立即使用Stub返回数据
 case immediate

 /// 一段时间间隔后使用Stub返回的数据.
 case delayed(seconds: TimeInterval)
}

      下面用个例子来总结一下这三个闭包的用法

      var sampleData: Data {
return "{'code': 0,'Token':'3764837egfdg8dfg8e93hr93'}".data(using:  String.Encoding.utf8)!
 }
//定义在SHChannelViewModelApiManager外头 
let endPointAction  = {(target: SHChannelViewModelApiManager) ->  Endpoint<SHChannelViewModelApiManager> in
  return Endpoint(
      url: URL(target: target).absoluteString,
      sampleResponseClosure: { .networkResponse(400, target.sampleData) },
      method: target.method,
      task: target.task,
      httpHeaderFields: target.headers
  )
}
//3秒后返回

let stubAction: (_ type: SHChannelViewModelApiManager) ->  Moya.StubBehavior  = { type in
      return Moya.StubBehavior.delayed(seconds: 3)

}
//创建moyaProvider
  let moyaProvider = MoyaProvider<SHChannelViewModelApiManager>(endpointClosure: endPointAction,  stubClosure: stubAction)
 //使用
 moyaProvider.request(SHChannelViewModelApiManager.getChannelList)........

    • Manager 就没什么好说的了,就是Alamofire的SessionManager

      public typealias Manager = Alamofire.SessionManager

      Manager是真正用来网络请求的类，Moya自己并不提供Manager类，Moya只是对其他网络请求类进行了简单的桥接（桥接模式）。这么做是为了让调用方可以轻易地定制、更换网络请求的库。比如你不想用Alamofire，可以十分简单的换成其他库,

    • callbackQueue作为回调队列传给Alamofire，如果为nil - 将使用Alamofire默认的,下面是找到的一个用途例子

          if let callbackQueue = callbackQueue {
              callbackQueue.async(execute: sendProgress)
          } else {
              sendProgress()
          }

    • plugins- Moya提供了一个插件机制，使我们可以建立自己的插件类来做一些额外的事情。比如写Log，显示“菊花”等。抽离出Plugin层的目的，就是让Provider职责单一，满足开闭原则。把和自己网络无关的行为抽离。避免各种业务揉在一起不利于扩展，（其实更像一个请求的生命周期,在该插入的地方调用）

    • trackInflights ，根据代码逻辑可以看出来，这是是否对重复请求情况的处理。其中有一个解释是：是否要跟踪重复网络请求。

          if trackInflights {
         objc_sync_enter(self)//递归锁
         var inflightCompletionBlocks = self.inflightRequests[endpoint]
         inflightCompletionBlocks?.append(pluginsWithCompletion)
         self.inflightRequests[endpoint] = inflightCompletionBlocks
         objc_sync_exit(self)

         if inflightCompletionBlocks != nil {
         // 如果存在，就是说明已经有一个已经重复的请求了,就把这个取消了
             return cancellableToken
         } else {
             objc_sync_enter(self)
             // 如果不存在 key 为 endpoint 的值，则初始化一个
             self.inflightRequests[endpoint] = [pluginsWithCompletion]
             objc_sync_exit(self)
         }
     }

      一个请求在 init 的时候将 trackInflights 设置为 true，那么在Moya 中就会存储这个请求的 endpoint。在返回数据的时候，如果需要跟踪了重复请求，那么就将一次实际发送请求返回的数据，多次返回。

    MoyaProvider 发送请求

    • 在 Moya 中 request 方法是一个统一的请求入口。只需要在方法中配置需要的参数，包括需要对应生成的请求地址，请求参数等通过枚举类型，十分清晰的分类和管理。利用 . 语法生成对应的枚举，然后依次生成 endpoint，URLRequest等

          @discardableResult
  open func request(_ target: Target,
                    callbackQueue: DispatchQueue? = .none,
                    progress: ProgressBlock? = .none,
                    completion: @escaping Completion) -> Cancellable {

      let callbackQueue = callbackQueue ?? self.callbackQueue
      return requestNormal(target, callbackQueue: callbackQueue, progress: progress, completion: completion)
  }

    • target就是传入的自定义枚举。

    • callbackQueue 同上

    • progress代表请求任务完成进度的回调，默认不使用

      public typealias ProgressBlock = (_ progress: ProgressResponse) -> Void

      再点进去ProgressResponse看看

      public struct ProgressResponse {

 /// The optional response of the request.
 public let response: Response?

 /// An object that conveys ongoing progress for a given request.
 public let progressObject: Progress?

 /// Initializes a `ProgressResponse`.
 public init(progress: Progress? = nil, response: Response? = nil) {
     self.progressObject = progress
     self.response = response
 }

 /// The fraction of the overall work completed by the progress object.
 public var progress: Double {
     return progressObject?.fractionCompleted ?? 1.0
 }

 /// A Boolean value stating whether the request is completed.
 public var completed: Bool {
     return progress == 1.0 && response != nil
 }
}

      由上可知，progressObject是一个Foundation框架的Progress对象，这是 iOS 7加入的专门用于监控任务进度的类

    • completion是请求完成后返回的回调

      public typealias Completion = (_ result: Result<Moya.Response, MoyaError>) -> Void

    3.2.MoyaProvider+Defaults

    MoyaProvider+Defaults里面就是 3 个默认方法，前面已经提到过，就不多做赘述了

    • defaultEndpointMapping 返回 Endpoint的默认方法
    • defaultRequestMapping 本质是返回URLRequest的默认方法
    • defaultAlamofireManager返回网络库的manager的默认方法（默认是Alamofire）

    3.3.MoyaProvider+Internal

    • Method是对Alamofire.HTTPMethod的拓展，添加supportsMultipart方法来判断，请求方式支不支持多种请求方式一起出现

      extension Method {
 /// A Boolean value determining whether the request supports multipart.
 public var supportsMultipart: Bool {
     switch self {
     case .post, .put, .patch, .connect:
         return true
     case .get, .delete, .head, .options, .trace:
         return false
     }
 }
}

    • requestNormal是MoyaProvider里request调的方法，方法里说明了，Moya在请求的时候到底做了什么

         func requestNormal(_ target: Target, callbackQueue: DispatchQueue?, progress: Moya.ProgressBlock?, completion: @escaping Moya.Completion) -> Cancellable {
   //获取endpoint、stubBehavior和初始化cancellableToken
     let endpoint = self.endpoint(target)
     let stubBehavior = self.stubClosure(target)
     //这个类控制是否取消请求任务
     let cancellableToken = CancellableWrapper()

     // 允许插件修改 response
     let pluginsWithCompletion: Moya.Completion = { result in
         let processedResult = self.plugins.reduce(result) { $1.process($0, target: target) }
         completion(processedResult)
     }
    //是否追踪重复请求
  if trackInflights {
         objc_sync_enter(self)//递归锁
         var inflightCompletionBlocks = self.inflightRequests[endpoint]
         inflightCompletionBlocks?.append(pluginsWithCompletion)
         self.inflightRequests[endpoint] = inflightCompletionBlocks
         objc_sync_exit(self)

         if inflightCompletionBlocks != nil {
         // 如果存在，就是说明已经有一个已经重复的请求了,就把这个取消了
             return cancellableToken
         } else {
             objc_sync_enter(self)
             // 如果不存在 key 为 endpoint 的值，则初始化一个
             self.inflightRequests[endpoint] = [pluginsWithCompletion]
             objc_sync_exit(self)
         }
     }
    //字面上理解，就是真正执行请求的下一步了。这个闭包，是在 endpoint → URLRequest 方法执行完成后的闭包
     let performNetworking = { (requestResult: Result<URLRequest, MoyaError>) in
     // 先判断这个请求是否取消，是则返回错误类型为 cancel 的错误提示数据
         if cancellableToken.isCancelled {
             self.cancelCompletion(pluginsWithCompletion, target: target)
             return
         }

         var request: URLRequest!

         switch requestResult {
         case .success(let urlRequest):
             request = urlRequest
         case .failure(let error):
             pluginsWithCompletion(.failure(error))
             return
         }

         // 允许插件修改 request
         let preparedRequest = self.plugins.reduce(request) { $1.prepare($0, target: target) }
       // 定义返回结果闭包，这里返回的是请求返回的数据映射成了 Result
         let networkCompletion: Moya.Completion = { result in
           if self.trackInflights {
             self.inflightRequests[endpoint]?.forEach { $0(result) }

             objc_sync_enter(self)
             self.inflightRequests.removeValue(forKey: endpoint)
             objc_sync_exit(self)
           } else {
           // 使用上面的闭包，通知所有插件，且返回结果
             pluginsWithCompletion(result)
           }
         }
  // 这一步就是执行请求的下一步了，将所有参数继续传递
         cancellableToken.innerCancellable = self.performRequest(target, request: preparedRequest, callbackQueue: callbackQueue, progress: progress, completion: networkCompletion, endpoint: endpoint, stubBehavior: stubBehavior)
     }
  // 接下去的就是将上面定义好的两个闭包，传入到 requestClosure 闭包中
     requestClosure(endpoint, performNetworking)

     return cancellableToken
 }

    • performRequest是上面执行请求的下一步，这个方法的内部实现，根据 switch stubBehavior 和 endpoint.task 来分别执行对应的请求方式。

     private func performRequest(_ target: Target, request: URLRequest, callbackQueue: DispatchQueue?, progress: Moya.ProgressBlock?, completion: @escaping Moya.Completion, endpoint: Endpoint<Target>, stubBehavior: Moya.StubBehavior) -> Cancellable {
        switch stubBehavior {
        case .never:
            switch endpoint.task {
            case .requestPlain, .requestData, .requestJSONEncodable, .requestParameters, .requestCompositeData, .requestCompositeParameters:
                return self.sendRequest(target, request: request, callbackQueue: callbackQueue, progress: progress, completion: completion)
            case .uploadFile(let file):
                return self.sendUploadFile(target, request: request, callbackQueue: callbackQueue, file: file, progress: progress, completion: completion)
            case .uploadMultipart(let multipartBody), .uploadCompositeMultipart(let multipartBody, _):
                guard !multipartBody.isEmpty && endpoint.method.supportsMultipart else {
                    fatalError("\(target) is not a multipart upload target.")
                }
                return self.sendUploadMultipart(target, request: request, callbackQueue: callbackQueue, multipartBody: multipartBody, progress: progress, completion: completion)
            case .downloadDestination(let destination), .downloadParameters(_, _, let destination):
                return self.sendDownloadRequest(target, request: request, callbackQueue: callbackQueue, destination: destination, progress: progress, completion: completion)
            }
        default:
            return self.stubRequest(target, request: request, callbackQueue: callbackQueue, completion: completion, endpoint: endpoint, stubBehavior: stubBehavior)
        }
    }

    3.4.Endpoint

    • Endpoint的初始化方法

       public init(url: String,
             sampleResponseClosure: @escaping SampleResponseClosure,
             method: Moya.Method,
             task: Task,
             httpHeaderFields: [String: String]?) {

     self.url = url
     self.sampleResponseClosure = sampleResponseClosure
     self.method = method
     self.task = task
     self.httpHeaderFields = httpHeaderFields

    • adding用于创建一个新的Endpoint的便利方法，其属性与接收方相同，但增加了HTTP请求头。

      open func adding(newHTTPHeaderFields: [String: String]) -> Endpoint<Target> {
     return Endpoint(url: url, sampleResponseClosure: sampleResponseClosure, method: method, task: task, httpHeaderFields: add(httpHeaderFields: newHTTPHeaderFields))
 }

    • replacing方法差不多，只是更换了Task

    • urlRequest()方法 转换Endpoint成URLRequest

    3.5.TargetType

    TargetType就是用于定义MoyaProvider的协议,自定义枚举需要签订的协议

    public protocol TargetType {

   /// The target's base `URL`.
   var baseURL: URL { get }

   /// The path to be appended to `baseURL` to form the full `URL`.
   var path: String { get }

   /// The HTTP method used in the request.
   var method: Moya.Method { get }

   /// Provides stub data for use in testing.
   var sampleData: Data { get }

   /// The type of HTTP task to be performed.
   var task: Task { get }

   /// A Boolean value determining whether the embedded target performs Alamofire validation. Defaults to `false`.
   var validate: Bool { get }

   /// The headers to be used in the request.
   var headers: [String: String]? { get }
}

    3.6.Response

    Response就是对对MoyaProvider.request的响应

    • Response的初始化

       public init(statusCode: Int, data: Data, request: URLRequest? = nil, response: HTTPURLResponse? = nil) {
     self.statusCode = statusCode //状态码
     self.data = data //返回的二进制数据
     self.request = request // URL 请求
     self.response = response// http 的 response
 }

      除此之外，还有自带的mapJSON和mapString用于将data转成 JSON或者字符串，map<D: Decodable>自带转模型，可以讲数据转换为签订Decodable类的对象，mapImage在返回 data数据为一个图片二进制数据时使用，直接转换成图片对象返回

         func mapImage() throws -> Image {
     guard let image = Image(data: data) else {
         throw MoyaError.imageMapping(self)
     }
     return image
 }

   func mapJSON(failsOnEmptyData: Bool = true) throws -> Any {
     do {
         return try JSONSerialization.jsonObject(with: data, options: .allowFragments)
     } catch {
         if data.count < 1 && !failsOnEmptyData {
             return NSNull()
         }
         throw MoyaError.jsonMapping(self)
     }
 }

     public func mapString(atKeyPath keyPath: String? = nil) throws -> String {
     if let keyPath = keyPath {
         // Key path was provided, try to parse string at key path
         guard let jsonDictionary = try mapJSON() as? NSDictionary,
             let string = jsonDictionary.value(forKeyPath: keyPath) as? String else {
                 throw MoyaError.stringMapping(self)
         }
         return string
     } else {
         // Key path was not provided, parse entire response as string
         guard let string = String(data: data, encoding: .utf8) else {
             throw MoyaError.stringMapping(self)
         }
         return string
     }
 }

   func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder()) throws -> D {
     let serializeToData: (Any) throws -> Data? = { (jsonObject) in
         guard JSONSerialization.isValidJSONObject(jsonObject) else {
             return nil
         }
         do {
             return try JSONSerialization.data(withJSONObject: jsonObject)
         } catch {
             throw MoyaError.jsonMapping(self)
         }
     }
     let jsonData: Data
     if let keyPath = keyPath {
         guard let jsonObject = (try mapJSON() as? NSDictionary)?.value(forKeyPath: keyPath) else {
             throw MoyaError.jsonMapping(self)
         }

         if let data = try serializeToData(jsonObject) {
             jsonData = data
         } else {
             let wrappedJsonObject = ["value": jsonObject]
             let wrappedJsonData: Data
             if let data = try serializeToData(wrappedJsonObject) {
                 wrappedJsonData = data
             } else {
                 throw MoyaError.jsonMapping(self)
             }
             do {
                 return try decoder.decode(DecodableWrapper<D>.self, from: wrappedJsonData).value
             } catch let error {
                 throw MoyaError.objectMapping(error, self)
             }
         }
     } else {
         jsonData = data
     }
     do {
         return try decoder.decode(D.self, from: jsonData)
     } catch let error {
         throw MoyaError.objectMapping(error, self)
     }
 }

    3.7.Plugin

    Moya Plugin接收回调（调用时机都是在MoyaProvider+Internal里），以在发送或接收请求时执行。例如，一个插件可以用于

    1.记录网络请求

2.隐藏和显示网络活动指示器

3.在请求中注入附加信息

    • prepare可以用来修改发送前的请求。（在 stub 测试之前）

          func prepare(_ request: URLRequest, target: TargetType) -> URLRequest

    • willSend在网络请求发送前调用（在 stub 测试之后）

          func willSend(_ request: RequestType, target: TargetType)

    • didReceive 在收到响应后，但在MoyaProvider调用其完成处理程序之前调用。

          func didReceive(_ result: Result<Moya.Response, MoyaError>, target: TargetType)

    • process在 completion前调用用来修改result

          func process(_ result: Result<Moya.Response, MoyaError>, target: TargetType) -> Result<Moya.Response, MoyaError>

    • RequestType是willSend需要传入的参数，它的设计遵循迪米特法则（最少知道），我们使用这个协议来代替Alamofire请求，以避免泄露这个抽象概念。Plugin应该是完全不知道Alamofire 的

      public protocol RequestType {

  /// Retrieve an `NSURLRequest` representation.
  var request: URLRequest? { get }

  /// Authenticates the request with a username and password.
  func authenticate(user: String, password: String, persistence: URLCredential.Persistence) -> Self

  /// Authenticates the request with an `NSURLCredential` instance.
  func authenticate(usingCredential credential: URLCredential) -> Self
 }

    3.8.AccessTokenPlugin

    AccessTokenPlugin可用于做JWT的 Bearer 认证 和 Basic 认证，也可以做OAuth认证，不过比较麻烦

    • 必要的时候通过prepare添加授权请求头来验证

          public func prepare(_ request: URLRequest, target: TargetType) -> URLRequest {
    guard let authorizable = target as? AccessTokenAuthorizable else { return request }

    let authorizationType = authorizable.authorizationType

    var request = request

    switch authorizationType {
    case .basic, .bearer:
    //添加Authorization，tokenClosure返回一个可应用请求头上的access token
        let authValue = authorizationType.rawValue + " " + tokenClosure()
        request.addValue(authValue, forHTTPHeaderField: "Authorization")
    case .none:
        break
    }

    return request
}

    3.9.CredentialsPlugin

    AccessTokenPlugin是做 HTTP 身份验证的，在 willSend里验证

    
  public func willSend(_ request: RequestType, target: TargetType) {
  //credentialsClosure返回一个 URLCredential对象，用于身份验证的系统 api
      if let credentials = credentialsClosure(target) {
      //通过Moya+Alamofire的“extension Request: RequestType { }” 可知，这个authenticate方法最后还是调用的 Alamofire的的认证方法
          _ = request.authenticate(usingCredential: credentials)
      }
  }

    3.10.NetworkActivityPlugin

    NetworkActivityPlugin还是比较简单的，就是单纯的抽离willSend和didReceive转变成NetworkActivityChangeType的began和ended，可以添加菊花的显示和隐藏

        public func willSend(_ request: RequestType, target: TargetType) {
      networkActivityClosure(.began, target)
  }

  /// Called by the provider as soon as a response arrives, even if the request is canceled.
  public func didReceive(_ result: Result<Moya.Response, MoyaError>, target: TargetType) {
      networkActivityClosure(.ended, target)
  }

    3.11.NetworkLoggerPlugin

    NetworkLoggerPlugin是网络日志的打印，还是在willSend和didReceive打印了网络状态

        public func willSend(_ request: RequestType, target: TargetType) {
     if let request = request as? CustomDebugStringConvertible, cURL {
         output(separator, terminator, request.debugDescription)
         return
     }
     outputItems(logNetworkRequest(request.request as URLRequest?))
 }

 public func didReceive(_ result: Result<Moya.Response, MoyaError>, target: TargetType) {
     if case .success(let response) = result {
         outputItems(logNetworkResponse(response.response, data: response.data, target: target))
     } else {
         outputItems(logNetworkResponse(nil, data: nil, target: target))
     }
 }

    作者：Mikebanana
    链接：https://juejin.cn/post/6899362830114357256

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