這個(gè)文件里面寫了三種參數(shù)編碼的方式：URLEncoding、JSONEncoding和PropertyListEncoding。
1. 輔助類型
// 用枚舉列舉了請(qǐng)求方法，并且用大寫的形式指定了rawValue
public enum HTTPMethod: String {
case options = "OPTIONS"
case get = "GET"
case head = "HEAD"
case post = "POST"
case put = "PUT"
case patch = "PATCH"
case delete = "DELETE"
case trace = "TRACE"
case connect = "CONNECT"
}
// Dictionary類型的參數(shù)
public typealias Parameters = [String: Any]
2. ParameterEncoding協(xié)議
規(guī)定了如何把參數(shù)編碼到請(qǐng)求當(dāng)中。
public protocol ParameterEncoding {
func encode(_ urlRequest: URLRequestConvertible, with parameters: Parameters?) throws -> URLRequest
}
3. URLEncoding
把參數(shù)直接編碼到URL中。
1). Destination
列舉了參數(shù)編碼到請(qǐng)求中的三種方式。
// methodDependent: 由請(qǐng)求方法自己決定肠虽，`GET`, `HEAD` 和 `DELETE`直接拼接到請(qǐng)求url中，其他方法放到HTTP body
// queryString: 直接拼接到請(qǐng)求url中
// httpBody: 放到HTTP body
public enum Destination {
case methodDependent, queryString, httpBody
}
2). 屬性和初始化
// 編碼方式是methodDependent的URLEncoding實(shí)例
public static var `default`: URLEncoding { return URLEncoding() }
// 編碼方式是methodDependent的URLEncoding實(shí)例玛追，其實(shí)跟default是相同的
public static var methodDependent: URLEncoding { return URLEncoding() }
// 編碼方式是queryString的URLEncoding實(shí)例
public static var queryString: URLEncoding { return URLEncoding(destination: .queryString) }
// 編碼方式是httpBody的URLEncoding實(shí)例
public static var httpBody: URLEncoding { return URLEncoding(destination: .httpBody) }
public let destination: Destination
public init(destination: Destination = .methodDependent) {
self.destination = destination
}
3). 編碼
// 實(shí)現(xiàn)ParameterEncoding協(xié)議
public func encode(_ urlRequest: URLRequestConvertible, with parameters: Parameters?) throws -> URLRequest {
var urlRequest = try urlRequest.asURLRequest()
// 如果沒有傳入?yún)?shù)税课，直接返回
guard let parameters = parameters else { return urlRequest }
// 把參數(shù)編碼到URL中
if let method = HTTPMethod(rawValue: urlRequest.httpMethod ?? "GET"), encodesParametersInURL(with: method) {
guard let url = urlRequest.url else {
throw AFError.parameterEncodingFailed(reason: .missingURL)
}
if var urlComponents = URLComponents(url: url, resolvingAgainstBaseURL: false), !parameters.isEmpty {
let percentEncodedQuery = (urlComponents.percentEncodedQuery.map { $0 + "&" } ?? "") + query(parameters)
urlComponents.percentEncodedQuery = percentEncodedQuery
urlRequest.url = urlComponents.url
}
} else { // 把參數(shù)編碼到HTTP body
if urlRequest.value(forHTTPHeaderField: "Content-Type") == nil {
urlRequest.setValue("application/x-www-form-urlencoded; charset=utf-8", forHTTPHeaderField: "Content-Type")
}
urlRequest.httpBody = query(parameters).data(using: .utf8, allowLossyConversion: false)
}
return urlRequest
}
// 根據(jù)傳入的key和value，返回處理好的查詢字符串組件
public func queryComponents(fromKey key: String, value: Any) -> [(String, String)] {
var components: [(String, String)] = []
if let dictionary = value as? [String: Any] { // value是字典
for (nestedKey, value) in dictionary {
// 用遞歸再次處理key和value
components += queryComponents(fromKey: "\(key)[\(nestedKey)]", value: value)
}
} else if let array = value as? [Any] { // value是數(shù)組
for value in array {
// 用遞歸再次處理key和value
components += queryComponents(fromKey: "\(key)[]", value: value)
}
} else if let value = value as? NSNumber { // value是NSNumber
if value.isBool {
// NSNumber其實(shí)是Bool類型痊剖，用1或者0代替
components.append((escape(key), escape((value.boolValue ? "1" : "0"))))
} else {
components.append((escape(key), escape("\(value)")))
}
} else if let bool = value as? Bool { // value是Bool類型韩玩，用1或者0代替
components.append((escape(key), escape((bool ? "1" : "0"))))
} else {
components.append((escape(key), escape("\(value)")))
}
return components
}
// 對(duì)字符串進(jìn)行百分號(hào)編碼。
// 下面這些分隔符保留原字符串：
// - General Delimiters: ":", "#", "[", "]", "@"
// - Sub-Delimiters: "!", "$", "&", "'", "(", ")", "*", "+", ",", ";", "="
public func escape(_ string: String) -> String {
let generalDelimitersToEncode = ":#[]@"
let subDelimitersToEncode = "!$&'()*+,;="
var allowedCharacterSet = CharacterSet.urlQueryAllowed
allowedCharacterSet.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
var escaped = ""
//==========================================================================================================
//
// 在iOS 8.1和8.2中陆馁，如果一次性對(duì)大量的中文字符進(jìn)行百分號(hào)編碼會(huì)造成crash找颓，所以進(jìn)行了分批處理
// （這個(gè)bug是國(guó)人發(fā)現(xiàn)的，具體可以查看這個(gè)issue：https://github.com/Alamofire/Alamofire/issues/206）
//
//==========================================================================================================
if #available(iOS 8.3, *) {
escaped = string.addingPercentEncoding(withAllowedCharacters: allowedCharacterSet) ?? string
} else {
let batchSize = 50
var index = string.startIndex
while index != string.endIndex {
let startIndex = index
let endIndex = string.index(index, offsetBy: batchSize, limitedBy: string.endIndex) ?? string.endIndex
let range = startIndex..<endIndex
let substring = string[range]
escaped += substring.addingPercentEncoding(withAllowedCharacters: allowedCharacterSet) ?? String(substring)
index = endIndex
}
}
return escaped
}
// 返回一個(gè)進(jìn)行了百分號(hào)編碼并且拼接好的字符串
private func query(_ parameters: [String: Any]) -> String {
var components: [(String, String)] = []
// `<`這個(gè)其實(shí)是一個(gè)其實(shí)是一個(gè)closure叮贩，意思是讓keys按照從小到大的順序重新排列
for key in parameters.keys.sorted(by: <) {
let value = parameters[key]!
components += queryComponents(fromKey: key, value: value)
}
return components.map { "\($0)=\($1)" }.joined(separator: "&")
}
// 判斷是否要把參數(shù)編碼到URL里
private func encodesParametersInURL(with method: HTTPMethod) -> Bool {
switch destination {
case .queryString:
return true
case .httpBody:
return false
default:
break
}
switch method {
case .get, .head, .delete:
return true
default:
return false
}
}
4. JSONEncoding
把參數(shù)以SJON類型編碼到請(qǐng)求體中击狮。
1). 屬性和初始化
// 默認(rèn)的JSONEncoding實(shí)例
public static var `default`: JSONEncoding { return JSONEncoding() }
// 用更好輸出效果的JSONEncoding實(shí)例
public static var prettyPrinted: JSONEncoding { return JSONEncoding(options: .prettyPrinted) }
public let options: JSONSerialization.WritingOptions
public init(options: JSONSerialization.WritingOptions = []) {
self.options = options
}
2). 編碼
// 把字典編碼到請(qǐng)求體中
public func encode(_ urlRequest: URLRequestConvertible, with parameters: Parameters?) throws -> URLRequest {
var urlRequest = try urlRequest.asURLRequest()
// 沒有參數(shù)，直接返回
guard let parameters = parameters else { return urlRequest }
do {
// 把參數(shù)序列化成JSON
let data = try JSONSerialization.data(withJSONObject: parameters, options: options)
// 設(shè)置Content-Type
if urlRequest.value(forHTTPHeaderField: "Content-Type") == nil {
urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
}
urlRequest.httpBody = data
} catch {
throw AFError.parameterEncodingFailed(reason: .jsonEncodingFailed(error: error))
}
return urlRequest
}
// 其實(shí)根上面那個(gè)方法幾乎一樣益老，只是第二個(gè)參數(shù)類型不同
public func encode(_ urlRequest: URLRequestConvertible, withJSONObject jsonObject: Any? = nil) throws -> URLRequest {
var urlRequest = try urlRequest.asURLRequest()
guard let jsonObject = jsonObject else { return urlRequest }
do {
// 把參數(shù)序列化成JSON
let data = try JSONSerialization.data(withJSONObject: jsonObject, options: options)
// 設(shè)置Content-Type
if urlRequest.value(forHTTPHeaderField: "Content-Type") == nil {
urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
}
urlRequest.httpBody = data
} catch {
throw AFError.parameterEncodingFailed(reason: .jsonEncodingFailed(error: error))
}
return urlRequest
}
5. PropertyListEncoding
把參數(shù)以PropertyList類型編碼到請(qǐng)求體中彪蓬。
1). 屬性和初始化
// 默認(rèn)的PropertyListEncoding實(shí)例，以xml的形式序列化
public static var `default`: PropertyListEncoding { return PropertyListEncoding() }
// 以xm的形式序列化的PropertyListEncoding實(shí)例
public static var xml: PropertyListEncoding { return PropertyListEncoding(format: .xml) }
// 以二進(jìn)制的形式序列化的PropertyListEncoding實(shí)例
public static var binary: PropertyListEncoding { return PropertyListEncoding(format: .binary) }
public let format: PropertyListSerialization.PropertyListFormat
public let options: PropertyListSerialization.WriteOptions
public init(
format: PropertyListSerialization.PropertyListFormat = .xml,
options: PropertyListSerialization.WriteOptions = 0)
{
self.format = format
self.options = options
}
2). 編碼
// 實(shí)現(xiàn)ParameterEncoding協(xié)議
public func encode(_ urlRequest: URLRequestConvertible, with parameters: Parameters?) throws -> URLRequest {
var urlRequest = try urlRequest.asURLRequest()
guard let parameters = parameters else { return urlRequest }
do {
// 把參數(shù)序列化成PropertyList
let data = try PropertyListSerialization.data(
fromPropertyList: parameters,
format: format,
options: options
)
// 設(shè)置Content-Type
if urlRequest.value(forHTTPHeaderField: "Content-Type") == nil {
urlRequest.setValue("application/x-plist", forHTTPHeaderField: "Content-Type")
}
urlRequest.httpBody = data
} catch {
throw AFError.parameterEncodingFailed(reason: .propertyListEncodingFailed(error: error))
}
return urlRequest
}
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