关于YTKNetwork
YTKNetwork是猿题库开发的一套基于AFNetworking的网络请求库，提供将AF请求封装成一个个接口对象来进行网络请求，提供更高级的抽象。
YTKNetwork 是猿题库 iOS 研发团队基于 AFNetworking 封装的 iOS 网络库，其实现了一套 High Level 的 API，提供了更高层次的网络访问抽象。YTKNetwork 现在同时被使用在猿题库公司的所有产品的 iOS 端，包括：猿题库、 小猿搜题、 猿辅导 、 粉笔直播课 。
YTKNetwork提供的功能
- 支持按时间缓存网络请求内容
- 支持按版本号缓存网络请求内容
- 支持统一设置服务器和 CDN 的地址
- 支持检查返回 JSON 内容的合法性
- 支持文件的断点续传
- 支持 block 和 delegate 两种模式的回调方式
- 支持批量的网络请求发送，并统一设置它们的回调（实现在YTKBatchRequest类中）
- 支持方便地设置有相互依赖的网络请求的发送，例如：发送请求A，根据请求A的结果，选择性的发送请求B和C，再根据B和C的结果，选择性的发送请求D。（实现在YTKChainRequest类中）
- 支持网络请求 URL 的 filter，可以统一为网络请求加上一些参数，或者修改一些路径。
- 定义了一套插件机制，可以很方便地为 YTKNetwork 增加功能。猿题库官方现在提供了一个插件，可以在某些网络请求发起时，在界面上显示"正在加载"的 HUD。
梳理关键类
YTKNetworkPrivate ：包含着一些便利方法，如 JSON 合法性，MD5 编码的方法， 从请求字典解析出参数等方法。
YTKNetworkConfig：网络配置方法，如基本 URL ，CDN 地址等
YTKBaseRequest ：YTKNetwork每个请求的虚拟基类，不直接使用，只是提供公共接口
YTKRequest ：继承于YTKBaseRequest实现其方法，并且添加了缓存相关的功能。如缓存验证，缓存保存等等。
YTKNetworkAgent：基本请求的操作代理，所有请求会被放在这里来执行。
基本请求
如Demo演示的，一个请求的过程是这样的
GetUserInfoApi *api = [[GetUserInfoApi alloc] initWithUserId:userId];
if ([api cacheJson]) {
NSDictionary *json = [api cacheJson];
NSLog(@"json = %@", json);
// show cached data
}
[api startWithCompletionBlockWithSuccess:^(YTKBaseRequest *request) {
NSLog(@"update ui");
} failure:^(YTKBaseRequest *request) {
NSLog(@"failed");
}];
我们的请求，需要继承YTKRequest并实现requestUrl，requestArgument等关键方法。
然后调用startWithCompletionBlockWithSuccess来开始一个请求。
在startWithCompletionBlockWithSuccess做了什么事呢？
在此方法中设置了成功和失败的2个Block，并且调用start方法,在start中进行缓存的判断。
if (self.ignoreCache) {
[super start];
return;
}
// check cache time
if ([self cacheTimeInSeconds] < 0) {
[super start];
return;
}
// check cache version
long long cacheVersionFileContent = [self cacheVersionFileContent];
if (cacheVersionFileContent != [self cacheVersion]) {
[super start];
return;
}
// check cache existance
NSString *path = [self cacheFilePath];
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath:path isDirectory:nil]) {
[super start];
return;
}
// check cache time
int seconds = [self cacheFileDuration:path];
if (seconds < 0 || seconds > [self cacheTimeInSeconds]) {
[super start];
return;
}
// load cache
_cacheJson = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
if (_cacheJson == nil) {
[super start];
return;
}
当缓存不存在，或者不需要缓存的时候会直接开始请求，
- (void)start {
[self toggleAccessoriesWillStartCallBack];
[[YTKNetworkAgent sharedInstance] addRequest:self];
}
可以看到YTKNetworkAgent来进行请求的持有和发送请求。
让我们聚焦YTKNetworkAgent内部实现细节。
在agent内部，持有了2个，存放请求的数组和AFHTTPRequestOperationManager
AFHTTPRequestOperationManager *_manager;
YTKNetworkConfig *_config;
NSMutableDictionary *_requestsRecord;
在addRequest的操作是
-
buildRequestUrl:构建请求的URL，这将在你实现的接口类里面获取请求URL和BaseURL相链接，并且使用YTKUrlFilterProtocol协议实现一些接口过滤的操作。 - 获取请求参数，拼接http请求头，
- 调用AF的get，post，patch等方法
- 添加到request到record数组
- (void)addRequest:(YTKBaseRequest *)request {
YTKRequestMethod method = [request requestMethod];
NSString *url = [self buildRequestUrl:request];
id param = request.requestArgument;
AFConstructingBlock constructingBlock = [request constructingBodyBlock];
if (request.requestSerializerType == YTKRequestSerializerTypeHTTP) {
_manager.requestSerializer = [AFHTTPRequestSerializer serializer];
} else if (request.requestSerializerType == YTKRequestSerializerTypeJSON) {
_manager.requestSerializer = [AFJSONRequestSerializer serializer];
}
_manager.requestSerializer.timeoutInterval = [request requestTimeoutInterval];
// if api need server username and password
NSArray *authorizationHeaderFieldArray = [request requestAuthorizationHeaderFieldArray];
if (authorizationHeaderFieldArray != nil) {
[_manager.requestSerializer setAuthorizationHeaderFieldWithUsername:(NSString *)authorizationHeaderFieldArray.firstObject
password:(NSString *)authorizationHeaderFieldArray.lastObject];
}
// if api need add custom value to HTTPHeaderField
NSDictionary *headerFieldValueDictionary = [request requestHeaderFieldValueDictionary];
if (headerFieldValueDictionary != nil) {
for (id httpHeaderField in headerFieldValueDictionary.allKeys) {
id value = headerFieldValueDictionary[httpHeaderField];
if ([httpHeaderField isKindOfClass:[NSString class]] && [value isKindOfClass:[NSString class]]) {
[_manager.requestSerializer setValue:(NSString *)value forHTTPHeaderField:(NSString *)httpHeaderField];
} else {
YTKLog(@"Error, class of key/value in headerFieldValueDictionary should be NSString.");
}
}
}
// if api build custom url request
NSURLRequest *customUrlRequest= [request buildCustomUrlRequest];
if (customUrlRequest) {
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:customUrlRequest];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
request.requestOperation = operation;
operation.responseSerializer = _manager.responseSerializer;
[_manager.operationQueue addOperation:operation];
} else {
if (method == YTKRequestMethodGet) {
if (request.resumableDownloadPath) {
// add parameters to URL;
NSString *filteredUrl = [YTKNetworkPrivate urlStringWithOriginUrlString:url appendParameters:param];
NSURLRequest *requestUrl = [NSURLRequest requestWithURL:[NSURL URLWithString:filteredUrl]];
AFDownloadRequestOperation *operation = [[AFDownloadRequestOperation alloc] initWithRequest:requestUrl
targetPath:request.resumableDownloadPath shouldResume:YES];
[operation setProgressiveDownloadProgressBlock:request.resumableDownloadProgressBlock];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
request.requestOperation = operation;
[_manager.operationQueue addOperation:operation];
} else {
request.requestOperation = [_manager GET:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
}
} else if (method == YTKRequestMethodPost) {
if (constructingBlock != nil) {
request.requestOperation = [_manager POST:url parameters:param constructingBodyWithBlock:constructingBlock
success:^(AFHTTPRequestOperation *operation, id responseObject) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
} else {
request.requestOperation = [_manager POST:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
}
} else if (method == YTKRequestMethodHead) {
request.requestOperation = [_manager HEAD:url parameters:param success:^(AFHTTPRequestOperation *operation) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
} else if (method == YTKRequestMethodPut) {
request.requestOperation = [_manager PUT:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
} else if (method == YTKRequestMethodDelete) {
request.requestOperation = [_manager DELETE:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
} else if (method == YTKRequestMethodPatch) {
request.requestOperation = [_manager PATCH:url parameters:param success:^(AFHTTPRequestOperation *operation, id responseObject) {
[self handleRequestResult:operation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[self handleRequestResult:operation];
}];
} else {
YTKLog(@"Error, unsupport method type");
return;
}
}
YTKLog(@"Add request: %@", NSStringFromClass([request class]));
[self addOperation:request];
}
之后就是漫长的网络请求。请求完成又是怎么处理的呢？
请求回调的处理在方法handleRequestResult中。其原理是判断是否请求成功，如验证服务器返回是不是成功，失败，或者网络连接失败，之后是调用delegate的回调，在往下是完成block。最后将request移除数组。
- (void)handleRequestResult:(AFHTTPRequestOperation *)operation {
NSString *key = [self requestHashKey:operation];
YTKBaseRequest *request = _requestsRecord[key];
YTKLog(@"Finished Request: %@", NSStringFromClass([request class]));
if (request) {
BOOL succeed = [self checkResult:request];
if (succeed) {
[request toggleAccessoriesWillStopCallBack];
[request requestCompleteFilter];
if (request.delegate != nil) {
[request.delegate requestFinished:request];
}
if (request.successCompletionBlock) {
request.successCompletionBlock(request);
}
[request toggleAccessoriesDidStopCallBack];
} else {
YTKLog(@"Request %@ failed, status code = %ld",
NSStringFromClass([request class]), (long)request.responseStatusCode);
[request toggleAccessoriesWillStopCallBack];
[request requestFailedFilter];
if (request.delegate != nil) {
[request.delegate requestFailed:request];
}
if (request.failureCompletionBlock) {
request.failureCompletionBlock(request);
}
[request toggleAccessoriesDidStopCallBack];
}
}
[self removeOperation:operation];
[request clearCompletionBlock];
}