iOS开发中对于网络缓存的处理

2019-3-8 王建伟 iOS开发

iOS开发中网络缓存苹果已经提供了比较好用的NSURLCache类，但是只支持GET请求，所以抛去原生的网络缓存类，这里介绍一个比较好用的网络缓存策略

1.创建类继承自AFHTTPSessionManager,然后根据load方法等妙用，自动监测网络状态，获取网络状态后对其处理，有网加载，没网本地取出。

+ (void)load { //设置网络请求的基本属性 JMHttpRequestMethod *httpMethod; httpMethod.requestSerializer = [AFJSONRequestSerializer serializer]; //设置请求的超时时间 httpMethod.requestSerializer.timeoutInterval = 20.f; //设置服务器返回结果的类型:JSON (AFJSONResponseSerializer,AFHTTPResponseSerializer) httpMethod.responseSerializer = [AFJSONResponseSerializer serializer]; httpMethod.responseSerializer.acceptableContentTypes = [NSSet setWithObjects: @"application/json", @"text/html", @"text/json", @"text/plain", @"text/javascript", @"text/xml", @"image/*", nil]; //创建数据库和表 _store = [[YTKKeyValueStore alloc] initDBWithName:httpCache]; [_store createTableWithName:httpCache]; //开始监测网络状态 [self startMonitoringNetworkStatus]; }

监测网络状态的方法我在上一篇文章中已经介绍了

GET和POST请求接口添加布尔属性，供选择是否选择对该URL缓存

/** GET 请求 带有进度回调的 API @param url 请求的url @param refreshCache 是否对该页面进行缓存 @param params 请求数据向服务器传的参数 @param progress 请求进度回调 @param success 请求成功回调 @param fail 请求失败回调 @return self */ + (JMHttpRequestMethod *)getWithUrl:(NSString *)url refreshCache:(BOOL)refreshCache params:(NSDictionary *)params progress:(void(^)(int64_t bytesRead, int64_t totalBytesRead))progress success:(void(^)(id responseObject))success fail:(void(^)(NSError *error))fail; /** POST 请求 带有进度回调的 API @param url 请求的url @param refreshCache 是否对该页面进行缓存 @param params 请求数据向服务器传的参数 @param progress 请求进度回调 @param success 请求成功回调 @param fail 请求失败回调 @return self */ + (JMHttpRequestMethod *)postWithUrl:(NSString *)url refreshCache:(BOOL)refreshCache params:(NSDictionary *)params progress:(void(^)(int64_t bytesRead, int64_t totalBytesRead))progress success:(void(^)(id responseObject))success fail:(void(^)(NSError *error))fail; ```

3.每次调用请求接口，先在本地数据库读取缓存，如果本地没有再进行请求，请求完之后对其缓存。这里以```GET ```请求为例， ```POST ```请求也一样的逻辑。

/** GET 请求 带有进度回调的 API @param url 请求的url @param refreshCache 是否对该页面进行缓存 @param params 请求数据向服务器传的参数 @param progress 请求进度回调 @param success 请求成功回调 @param fail 请求失败回调 @return self */ (JMHttpRequestMethod *)getWithUrl:(NSString *)url refreshCache:(BOOL)refreshCache params:(NSDictionary *)params progress:(void(^)(int64_t bytesRead, int64_t totalBytesRead))progress success:(void(^)(id responseObject))success fail:(void(^)(NSError *error))fail { JMHttpRequestMethod *request = nil; //先获取当前的网络状态有网的话，进行请求 if ([JMHttpRequestMethod getCurrentNetWorkStatus]) { //判断是否对该url进行缓存 if (!refreshCache) { [self requestNotCacheWithHttpMethod:0 url:url params:params progress:progress success:success fail:fail]; }else { //如果进行缓存，先从本地取出缓存的数据 NSDictionary *dict = [_store getObjectById:url fromTable:httpCache]; //如果本地有数据，直接回调，否则进行网络请求 if (dict) { success(dict); }else { [[self manager] GET:url parameters:params progress:^(NSProgress * _Nonnull downloadProgress) { progress(downloadProgress.completedUnitCount, downloadProgress.totalUnitCount); } success:^(NSURLSessionDataTask * _Nonnull task, id _Nullable responseObject) { // 请求到数据后就进行存储，然后回调请求成功的数据 [_store putObject:responseObject withId:url intoTable:httpCache]; success(responseObject); NSLog(@"\nRequest success, URL: %@\n params:%@\n response:%@\n\n",url,params,responseObject); } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) { fail(error); NSLog(@"error = %@",error.description); }]; } } } else { //当前没有网络，然后从本地数据库中取出数据 NSDictionary *dict = [_store getObjectById:url fromTable:httpCache]; //本地有数据的话，进行回调，否则取出失败打印信息 if (dict) { success(dict); }else { NSLog(@"当前为无网络状态，本地也没有缓存数据"); } } return request; /** 不进行缓存时，进行网络请求的方法 @param httpMethod 0 ： 代表GET请求 1：代表POST请求 @param url 请求的url @param params 请求参数 @param progress 请求进度回调 @param success 请求成功回调 @param fail 请求失败回调 */ (void)requestNotCacheWithHttpMethod:(NSInteger)httpMethod url:(NSString *)url params:(NSDictionary *)params progress:(void(^)(int64_t bytesRead, int64_t totalBytesRead))progress success:(void(^)(id responseObject))success fail:(void(^)(NSError *error))fail { if (httpMethod == 0) { [[self manager]GET:url parameters:params progress:^(NSProgress * _Nonnull downloadProgress) { progress(downloadProgress.completedUnitCount, downloadProgress.totalUnitCount); } success:^(NSURLSessionDataTask * _Nonnull task, id _Nullable responseObject) { success(responseObject); NSLog(@"\nRequest success, URL: %@\n params:%@\n response:%@\n\n",url,params,responseObject); } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) { fail(error); }]; }else { [[self manager ]POST:url parameters:params progress:^(NSProgress * _Nonnull uploadProgress) { progress(uploadProgress.completedUnitCount, uploadProgress.totalUnitCount); } success:^(NSURLSessionDataTask * _Nonnull task, id _Nullable responseObject) { success(responseObject); NSLog(@"\nRequest success, URL: %@\n params:%@\n response:%@\n\n",url,params,responseObject); } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) { fail(error); }]; } }

4.提供清楚缓存和获取文件大小接口

/** 获取网络缓存 文件大小 @return size 直接返回字符串，单位M。保留两位小数。举例 1.12M */ (NSString )fileSizeWithDBPath { NSFileManager manager = [NSFileManager defaultManager]; if ([manager fileExistsAtPath:[PATH_OF_NetWork stringByAppendingPathComponent:httpCache]]){ unsigned long long fileSize = [[manager attributesOfItemAtPath:[PATH_OF_NetWork stringByAppendingPathComponent:httpCache] error:nil] fileSize]; NSString *size = [NSString stringWithFormat:@"%.2fM",fileSize/1024.0/1024.0]; return size; }else { return @"0M"; } return 0; } /** 清除所有网络缓存 */ (void)cleanNetWorkRefreshCache { NSError *error; BOOL isSuccess = [[NSFileManager defaultManager]removeItemAtPath:[PATH_OF_NetWork stringByAppendingPathComponent:httpCache] error:&error]; if (isSuccess) { NSLog(@"clean cache file is success"); }else { if ([PATH_OF_NetWork stringByAppendingPathComponent:httpCache]) { NSLog(@"error:%@",error.description); }else { NSLog(@"error: cache file is not exist"); } } }

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