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ios 多线程文件下载与上传, post数据
一、文件下载
获取资源文件大小有两张方式
1、
[objc] view plaincopy
- HTTP HEAD方法
- NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:0 timeoutInterval:kTimeout];
- request.HTTPMethod = @"HEAD";
- [NSURLConnection sendAsynchronousRequest:request queue:self.myQueue completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
- NSLog(@"%@", response);
- NSLog(@"---------------");
- NSLog(@"%@", data);
- }];
- 运行测试代码可以发现,HEAD方法只是返回资源信息,而不会返回数据体
- 应用场景:
- 获取资源Mimetype
- 获取资源文件大小,用于端点续传或多线程下载
2
[objc] view plaincopy
- 使用块代码获取网络资源大小的方法
- - (void)fileSizeWithURL:(NSURL *)url completion:(void (^)(long long contentLength))completion
- {
- NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:0 timeoutInterval:kTimeout];
- request.HTTPMethod = @"HEAD";
- NSURLResponse *response = nil;
- [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:NULL];
- completion(response.expectedContentLength);
- }
确定每次下载数据包的伪代码实现
[objc] view plaincopy
- - (void)downloadFileWithURL:(NSURL *)url
- {
- [self fileSizeWithURL:url completion:^(long long contentLength) {
- NSLog(@"文件总大小:%lld", contentLength);
- // 根据大小下载文件
- while (contentLength > kDownloadBytes) {
- NSLog(@"每次下载长度:%lld", (long long)kDownloadBytes);
- contentLength -= kDownloadBytes;
- }
- NSLog(@"最后下载字节数:%lld", contentLength);
- }];
- }
HTTP Range的示例
通过设置Range可以指定每次从网路下载数据包的大小
Range示例
bytes=0-499 从0到499的头500个字节
bytes=500-999 从500到999的第二个500字节
bytes=500- 从500字节以后的所有字节
bytes=-500 最后500个字节
bytes=500-599,800-899 同时指定几个范围
Range小结
- 用于分隔
前面的数字表示起始字节数
后面的数组表示截止字节数,没有表示到末尾
, 用于分组,可以一次指定多个Range,不过很少用
[objc] view plaincopy
- 分段Range代码实现
- long long fromBytes = 0;
- long long toBytes = 0;
- while (contentLength > kDownloadBytes) {
- toBytes = fromBytes + kDownloadBytes - 1;
- NSString *range = [NSString stringWithFormat:@"bytes=%lld-%lld", fromBytes, toBytes];
- NSLog(@"range %@", range);
- fromBytes += kDownloadBytes;
- contentLength -= kDownloadBytes;
- }
- fromBytes = fromBytes + contentLength - 1;
- NSString *range = [NSString stringWithFormat:@"bytes=%lld-%lld", fromBytes, toBytes];
- NSLog(@"range %@", range);
[objc] view plaincopy
- 分段下载文件
- NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:kTimeout];
- NSString *range = [NSString stringWithFormat:@"bytes=%lld-%lld", from, end];
- [request setValue:range forHTTPHeaderField:@"Range"];
- NSURLResponse *response = nil;
- NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:NULL];
- NSLog(@"%@-%@-%ld", range, response, (unsigned long)data.length);
- 提示:
- 如果GET包含Range请求头,响应会以状态码206(PartialContent)返回而不是200(OK)
[objc] view plaincopy
- 将数据写入文件
- // 打开缓存文件
- NSFileHandle *fp = [NSFileHandle fileHandleForWritingAtPath:self.cachePath];
- // 如果文件不存在,直接写入数据
- if (!fp) {
- [data writeToFile:self.cachePath atomically:YES];
- } else {
- // 移动到文件末尾
- [fp seekToEndOfFile];
- // 将数据文件追加到文件末尾
- [fp writeData:data];
- // 关闭文件句柄
- [fp closeFile];
- }
[objc] view plaincopy
- 检查文件大小
- // 判断文件是否存在
- if ([[NSFileManager defaultManager] fileExistsAtPath:self.cachePath]) {
- NSDictionary *dict = [[NSFileManager defaultManager] attributesOfItemAtPath:self.cachePath error:NULL];
- return [dict[NSFileSize] longLongValue];
- } else {
- return 0;
- }
- 提示:由于数据是追加的,为了避免重复从网络下载文件,在下载之前
- 判断缓存路径中文件是否已经存在
- 如果存在检查文件大小
- 如果文件大小与网络资源大小一致,则不再下载
全部代码如下
[objc] view plaincopy
- //
- // MJViewController.m
- // 01.文件下载
- //
- // Created by apple on 14-4-29.
- // Copyright (c) 2014年 itcast. All rights reserved.
- //
- #import "MJViewController.h"
- #import "FileDownload.h"
- @interface MJViewController ()
- @property (nonatomic, strong) FileDownload *download;
- @property (weak, nonatomic) IBOutlet UIImageView *imageView;
- @end
- @implementation MJViewController
- - (void)viewDidLoad
- {
- [super viewDidLoad];
- self.download = [[FileDownload alloc] init];
- [self.download downloadFileWithURL:[NSURL URLWithString:@"http://localhost/itcast/images/head4.png"] completion:^(UIImage *image) {
- self.imageView.image = image;
- }];
- }
- @end
[objc] view plaincopy
- //
- // FileDownload.m
- // 01.文件下载
- //
- // Created by apple on 14-4-29.
- // Copyright (c) 2014年 itcast. All rights reserved.
- //
- #import "FileDownload.h"
- #import "NSString+Password.h"
- #define kTimeOut 2.0f
- // 每次下载的字节数
- #define kBytesPerTimes 20250
- @interface FileDownload()
- @property (nonatomic, strong) NSString *cacheFile;
- @property (nonatomic, strong) UIImage *cacheImage;
- @end
- @implementation FileDownload
- /**
- 为了保证开发的简单,所有方法都不使用多线程,所有的注意力都保持在文件下载上
- 在开发中如果碰到比较绕的计算问题时,建议:
- 1> 测试数据不要太大
- 2> 测试数据的数值变化,能够用笔算计算出准确的数值
- 3> 编写代码对照测试
- */
- //- (NSString *)cacheFile
- //{
- // if (!_cacheFile) {
- // NSString *cacheDir = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)[0];
- // _cacheFile = [cacheDir stringByAppendingPathComponent:@"123.png"];
- // }
- // return _cacheFile;
- //}
- - (UIImage *)cacheImage
- {
- if (!_cacheImage) {
- _cacheImage = [UIImage imageWithContentsOfFile:self.cacheFile];
- }
- return _cacheImage;
- }
- - (void)setCacheFile:(NSString *)urlStr
- {
- NSString *cacheDir = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)[0];
- urlStr = [urlStr MD5];
- _cacheFile = [cacheDir stringByAppendingPathComponent:urlStr];
- }
- - (void)downloadFileWithURL:(NSURL *)url completion:(void (^)(UIImage *image))completion
- {
- // GCD中的串行队列异步方法
- dispatch_queue_t q = dispatch_queue_create("cn.itcast.download", DISPATCH_QUEUE_SERIAL);
- dispatch_async(q, ^{
- NSLog(@"%@", [NSThread currentThread]);
- // 把对URL进行MD5加密之后的结果当成文件名
- self.cacheFile = [url absoluteString];
- // 1. 从网络下载文件,需要知道这个文件的大小
- long long fileSize = [self fileSizeWithURL:url];
- // 计算本地缓存文件大小
- long long cacheFileSize = [self localFileSize];
- if (cacheFileSize == fileSize) {
- dispatch_async(dispatch_get_main_queue(), ^{
- completion(self.cacheImage);
- });
- NSLog(@"文件已经存在");
- return;
- }
- // 2. 确定每个数据包的大小
- long long fromB = 0;
- long long toB = 0;
- // 计算起始和结束的字节数
- while (fileSize > kBytesPerTimes) {
- // 20480 + 20480
- //
- toB = fromB + kBytesPerTimes - 1;
- // 3. 分段下载文件
- [self downloadDataWithURL:url fromB:fromB toB:toB];
- fileSize -= kBytesPerTimes;
- fromB += kBytesPerTimes;
- }
- [self downloadDataWithURL:url fromB:fromB toB:fromB + fileSize - 1];
- dispatch_async(dispatch_get_main_queue(), ^{
- completion(self.cacheImage);
- });
- });
- }
- #pragma mark 下载指定字节范围的数据包
- /**
- NSURLRequestUseProtocolCachePolicy = 0, // 默认的缓存策略,内存缓存
- NSURLRequestReloadIgnoringLocalCacheData = 1, // 忽略本地的内存缓存
- NSURLRequestReloadIgnoringCacheData
- */
- - (void)downloadDataWithURL:(NSURL *)url fromB:(long long)fromB toB:(long long)toB
- {
- NSLog(@"数据包:%@", [NSThread currentThread]);
- NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:kTimeOut];
- // 指定请求中所要GET的字节范围
- NSString *range = [NSString stringWithFormat:@"Bytes=%lld-%lld", fromB, toB];
- [request setValue:range forHTTPHeaderField:@"Range"];
- NSLog(@"%@", range);
- NSURLResponse *response = nil;
- NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:NULL];
- // 写入文件,覆盖文件不会追加
- // [data writeToFile:@"/Users/aplle/Desktop/1.png" atomically:YES];
- [self appendData:data];
- NSLog(@"%@", response);
- }
- #pragma mark - 读取本地缓存文件大小
- - (long long)localFileSize
- {
- // 读取本地文件信息
- NSDictionary *dict = [[NSFileManager defaultManager] attributesOfItemAtPath:self.cacheFile error:NULL];
- NSLog(@"%lld", [dict[NSFileSize] longLongValue]);
- return [dict[NSFileSize] longLongValue];
- }
- #pragma mark - 追加数据到文件
- - (void)appendData:(NSData *)data
- {
- // 判断文件是否存在
- NSFileHandle *fp = [NSFileHandle fileHandleForWritingAtPath:self.cacheFile];
- // 如果文件不存在创建文件
- if (!fp) {
- [data writeToFile:self.cacheFile atomically:YES];
- } else {
- // 如果文件已经存在追加文件
- // 1> 移动到文件末尾
- [fp seekToEndOfFile];
- // 2> 追加数据
- [fp writeData:data];
- // 3> 写入文件
- [fp closeFile];
- }
- }
- #pragma mark - 获取网络文件大小
- - (long long)fileSizeWithURL:(NSURL *)url
- {
- // 默认是GET
- NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:0 timeoutInterval:kTimeOut];
- // HEAD 头,只是返回文件资源的信息,不返回具体是数据
- // 如果要获取资源的MIMEType,也必须用HEAD,否则,数据会被重复下载两次
- request.HTTPMethod = @"HEAD";
- // 使用同步方法获取文件大小
- NSURLResponse *response = nil;
- [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:NULL];
- // expectedContentLength文件在网络上的大小
- NSLog(@"%lld", response.expectedContentLength);
- return response.expectedContentLength;
- }
- @end
二、文件上传
代码如下
[objc] view plaincopy
- //
- // MJViewController.m
- // 02.Post上传
- //
- // Created by apple on 14-4-29.
- // Copyright (c) 2014年 itcast. All rights reserved.
- //
- #import "MJViewController.h"
- #import "UploadFile.h"
- @interface MJViewController ()
- @end
- @implementation MJViewController
- - (void)viewDidLoad
- {
- [super viewDidLoad];
- UploadFile *upload = [[UploadFile alloc] init];
- NSString *urlString = @"http://localhost/upload.php";
- NSString *path = [[NSBundle mainBundle] pathForResource:@"头像1.png" ofType:nil];
- NSData *data = [NSData dataWithContentsOfFile:path];
- [upload uploadFileWithURL:[NSURL URLWithString:urlString] data:data];
- }
- @end
[objc] view plaincopy
- //
- // UploadFile.m
- // 02.Post上传
- //
- // Created by apple on 14-4-29.
- // Copyright (c) 2014年 itcast. All rights reserved.
- //
- #import "UploadFile.h"
- @implementation UploadFile
- // 拼接字符串
- static NSString *boundaryStr = @"--"; // 分隔字符串
- static NSString *randomIDStr; // 本次上传标示字符串
- static NSString *uploadID; // 上传(php)脚本中,接收文件字段
- - (instancetype)init
- {
- self = [super init];
- if (self) {
- randomIDStr = @"itcast";
- uploadID = @"uploadFile";
- }
- return self;
- }
- #pragma mark - 私有方法
- - (NSString *)topStringWithMimeType:(NSString *)mimeType uploadFile:(NSString *)uploadFile
- {
- NSMutableString *strM = [NSMutableString string];
- [strM appendFormat:@"%@%@\n", boundaryStr, randomIDStr];
- [strM appendFormat:@"Content-Disposition: form-data; name=\"%@\"; filename=\"%@\"\n", uploadID, uploadFile];
- [strM appendFormat:@"Content-Type: %@\n\n", mimeType];
- NSLog(@"%@", strM);
- return [strM copy];
- }
- - (NSString *)bottomString
- {
- NSMutableString *strM = [NSMutableString string];
- [strM appendFormat:@"%@%@\n", boundaryStr, randomIDStr];
- [strM appendString:@"Content-Disposition: form-data; name=\"submit\"\n\n"];
- [strM appendString:@"Submit\n"];
- [strM appendFormat:@"%@%@--\n", boundaryStr, randomIDStr];
- NSLog(@"%@", strM);
- return [strM copy];
- }
- #pragma mark - 上传文件
- - (void)uploadFileWithURL:(NSURL *)url data:(NSData *)data
- {
- // 1> 数据体
- NSString *topStr = [self topStringWithMimeType:@"image/png" uploadFile:@"头像1.png"];
- NSString *bottomStr = [self bottomString];
- NSMutableData *dataM = [NSMutableData data];
- [dataM appendData:[topStr dataUsingEncoding:NSUTF8StringEncoding]];
- [dataM appendData:data];
- [dataM appendData:[bottomStr dataUsingEncoding:NSUTF8StringEncoding]];
- // 1. Request
- NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:0 timeoutInterval:2.0f];
- // dataM出了作用域就会被释放,因此不用copy
- request.HTTPBody = dataM;
- // 2> 设置Request的头属性
- request.HTTPMethod = @"POST";
- // 3> 设置Content-Length
- NSString *strLength = [NSString stringWithFormat:@"%ld", (long)dataM.length];
- [request setValue:strLength forHTTPHeaderField:@"Content-Length"];
- // 4> 设置Content-Type
- NSString *strContentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", randomIDStr];
- [request setValue:strContentType forHTTPHeaderField:@"Content-Type"];
- // 3> 连接服务器发送请求
- [NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
- NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
- NSLog(@"%@", result);
- }];
- }
- @end
ios 多线程文件下载与上传, post数据
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