ios 多线程文件下载与上传， post数据

首页 > 代码库 > ios 多线程文件下载与上传， post数据

ios 多线程文件下载与上传， post数据

2024-08-09 19:02:04 221人阅读

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

[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.
//
#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.
//
#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.
//
#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.
//
#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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ios 多线程文件下载与上传， post数据

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