说明:NSURLSession实在IOS7推出的一种新技术,用来代替NSURLConnection.
利用NSURLSession可以更加方便的实现与服务器的交互,更方便的下载上传文件。
NSURLSession的常用方法:
// 常用的类方法
+ (NSURLSession *)sharedSession;
+ (NSURLSession *)sessionWithConfiguration:(NSURLSessionConfiguration *)configuration;
+ (NSURLSession *)sessionWithConfiguration:(NSURLSessionConfiguration *)configuration delegate:(id <NSURLSessionDelegate>)delegate delegateQueue:(NSOperationQueue *)queue;
// 任务:任何一个请求都是任务
// NSURLSessionDataTask : 普通的GET\POST请求
// NSURLSessionDownloadTask : 文件下载
// NSURLSessionUploadTask : 文件上传
// 下面是常用的创建任务的方法
/*
* NSURLSessionTask objects are always created in a suspended state and
* must be sent the -resume message before they will execute.
*/
/* Creates a data task with the given request. The request may have a body stream. */
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request;
/* Creates a data task to retrieve the contents of the given URL. */
- (NSURLSessionDataTask *)dataTaskWithURL:(NSURL *)url;
/* Creates an upload task with the given request. The body of the request will be created from the file referenced by fileURL */
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request fromFile:(NSURL *)fileURL;
/* Creates an upload task with the given request. The body of the request is provided from the bodyData. */
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request fromData:(NSData *)bodyData;
/* Creates an upload task with the given request. The previously set body stream of the request (if any) is ignored and the URLSession:task:needNewBodyStream: delegate will be called when the body payload is required. */
- (NSURLSessionUploadTask *)uploadTaskWithStreamedRequest:(NSURLRequest *)request;
/* Creates a download task with the given request. */
- (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request;
/* Creates a download task to download the contents of the given URL. */
- (NSURLSessionDownloadTask *)downloadTaskWithURL:(NSURL *)url;
/* Creates a download task with the resume data. If the download cannot be successfully resumed, URLSession:task:didCompleteWithError: will be called. */
- (NSURLSessionDownloadTask *)downloadTaskWithResumeData:(NSData *)resumeData;
当需要有下载进度时,需要使用协议,实现NSURLSessionDownloadDelegate方法。
下面是利用NSURLSession实现的下载代码:
//
// ViewController.m
// NSURLSession-的使用
//
// Created by apple on 15-5-20.
// Copyright (c) 2015年 zzu. All rights reserved.
//
#import "ViewController.h"
@interface ViewController ()<NSURLSessionDownloadDelegate>
@property (nonatomic,strong) NSURLSession *session;
@end
@implementation ViewController
// 任务:任何一个请求都是任务
// NSURLSessionDataTask : 普通的GET\POST请求
// NSURLSessionDownloadTask : 文件下载
// NSURLSessionUploadTask : 文件上传
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
// NSLog(@"%@",caches);
[self downloadTask2];
}
/** * 下载任务:不能看到下载进度 */
- (void)downloadTask
{
NSURLSession *session = [NSURLSession sharedSession];
NSURL *url = [NSURL URLWithString:@"http://localhost:8080/MJServer/resources/images/minion_01.png"];
// 创建一个下载task
NSURLSessionDownloadTask *task = [session downloadTaskWithURL:url completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
// location : 临时文件的路径(下载好的文件)
NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSString *file = [caches stringByAppendingPathComponent:response.suggestedFilename];
// 将临时文件剪切或复制caches文件
NSFileManager *mgr = [NSFileManager defaultManager];
[mgr moveItemAtPath:location.path toPath:file error:nil];
}];
// 开始任务
[task resume];
}
- (void)downloadTask2
{
NSURLSessionConfiguration *cfg = [NSURLSessionConfiguration defaultSessionConfiguration];
// 得到session对象
NSURLSession *session = [NSURLSession sessionWithConfiguration:cfg delegate:self delegateQueue:[NSOperationQueue mainQueue]];
// 创建一个下载task
NSURL *url= [NSURL URLWithString:@"http://localhost:8080/MJServer/resources/videos/test.zip"];
NSURLSessionDownloadTask *task = [session downloadTaskWithURL:url];
// 开始任务
[task resume];
// 如果下载任务设置了completionHandle这个block,也实现了下载的代理方法,则优先执行block
}
#pragma mark - <NSURLSessionDownloadDelegate>协议的方法
// 下载完毕后调用
// location : 临时文件的路径 (下载好的文件)
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location
{
NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSString *file = [caches stringByAppendingPathComponent:downloadTask.response.suggestedFilename];
// 将临时文件剪切或复制到caches文件夹
NSFileManager *mgr = [NSFileManager defaultManager];
[mgr moveItemAtPath:location.path toPath:file error:nil];
}
// 恢复下载时调用
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didResumeAtOffset:(int64_t)fileOffset expectedTotalBytes:(int64_t)expectedTotalBytes
{
}
//每当下载完一部分数据时,就会调用
// bytesWriten : 本次调用写了多少数据
// totalBytesWritten : 累计写了多少数据到沙盒中
// totalBytesExceptedToWrite : 文件总长度
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
double progress = (double)totalBytesWritten / totalBytesExpectedToWrite;
NSLog(@"下载进度----- %f",progress);
}
@end
带断点续传功能的问文件下载:
//
// ZQViewController.m
//
#import "ZQViewController.h"
@interface ZQViewController () <NSURLSessionDownloadDelegate, NSURLSessionDataDelegate>
@property (weak, nonatomic) IBOutlet UIProgressView *progressView;
- (IBAction)download:(UIButton *)sender;
@property (nonatomic, strong) NSURLSessionDownloadTask *task;
@property (nonatomic, strong) NSData *resumeData;
@property (nonatomic, strong) NSURLSession *session;
@end
@implementation HMViewController
- (NSURLSession *)session
{
if (!_session) {
// 获得session
NSURLSessionConfiguration *cfg = [NSURLSessionConfiguration defaultSessionConfiguration];
self.session = [NSURLSession sessionWithConfiguration:cfg delegate:self delegateQueue:[NSOperationQueue mainQueue]];
}
return _session;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (IBAction)download:(UIButton *)sender {
// 按钮状态取反
sender.selected = !sender.isSelected;
if (self.task == nil) { // 开始(继续)下载
if (self.resumeData) { // 恢复
[self resume];
} else { // 开始
[self start];
}
} else { // 暂停
[self pause];
}
}
/** * 从零开始 */
- (void)start
{
// 1.创建一个下载任务
NSURL *url = [NSURL URLWithString:@"http://192.168.15.172:8080/MJServer/resources/videos/minion_01.mp4"];
self.task = [self.session downloadTaskWithURL:url];
// 2.开始任务
[self.task resume];
}
/** * 恢复(继续) */
- (void)resume
{
// 传入上次暂停下载返回的数据,就可以恢复下载
self.task = [self.session downloadTaskWithResumeData:self.resumeData];
// 开始任务
[self.task resume];
// 清空
self.resumeData = nil;
}
/** * 暂停 */
- (void)pause
{
__weak typeof(self) vc = self;
[self.task cancelByProducingResumeData:^(NSData *resumeData) {
// resumeData : 包含了继续下载的开始位置\下载的url
vc.resumeData = resumeData;
vc.task = nil;
}];
}
#pragma mark - NSURLSessionDownloadDelegate
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
didFinishDownloadingToURL:(NSURL *)location
{
NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
// response.suggestedFilename : 建议使用的文件名,一般跟服务器端的文件名一致
NSString *file = [caches stringByAppendingPathComponent:downloadTask.response.suggestedFilename];
// 将临时文件剪切或者复制Caches文件夹
NSFileManager *mgr = [NSFileManager defaultManager];
// AtPath : 剪切前的文件路径
// ToPath : 剪切后的文件路径
[mgr moveItemAtPath:location.path toPath:file error:nil];
}
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
didWriteData:(int64_t)bytesWritten
totalBytesWritten:(int64_t)totalBytesWritten
totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
NSLog(@"获得下载进度--%@", [NSThread currentThread]);
// 获得下载进度
self.progressView.progress = (double)totalBytesWritten / totalBytesExpectedToWrite;
}
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
didResumeAtOffset:(int64_t)fileOffset
expectedTotalBytes:(int64_t)expectedTotalBytes
{
}
//- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data
//{
//
//}
//
//- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler
//{
//
//}
@end