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ios 文件上傳， post數據

編輯：IOS開發綜合

一、文件下載

獲取資源文件大小有兩張方式

1、

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);
}];
運行測試代碼可以發現，HEAD方法只是返回資源信息，而不會返回數據體
應用場景：
獲取資源Mimetype
獲取資源文件大小，用於端點續傳或多線程下載

使用塊代碼獲取網絡資源大小的方法
- (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);
}

確定每次下載數據包的偽代碼實現

- (void)downloadFileWithURL:(NSURL *)url
{
    [self fileSizeWithURL:url completion:^(long long contentLength) {
        NSLog(@"文件總大小：%lld", contentLength);        
        // 根據大小下載文件
               while (contentLength > kDownloadBytes) {
            NSLog(@"每次下載長度：%lld", (long long)kDownloadBytes);
            contentLength -= kDownloadBytes;
        }
        NSLog(@"最後下載字節數：%lld", contentLength);
    }];
}

HTTP Range的示例
通過設置Range可以指定每次從網路下載數據包的大小
Range示例
bytes=0-499 從0到499的頭500個字節
bytes=500-999 從500到999的第二個500字節
bytes=500- 從500字節以後的所有字節
bytes=-500 最後500個字節
bytes=500-599,800-899 同時指定幾個范圍
Range小結
- 用於分隔
前面的數字表示起始字節數
後面的數組表示截止字節數，沒有表示到末尾
, 用於分組，可以一次指定多個Range，不過很少用

分段Range代碼實現
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);

分段下載文件
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請求頭，響應會以狀態碼206（PartialContent）返回而不是200（OK）

將數據寫入文件
// 打開緩存文件
NSFileHandle *fp = [NSFileHandle fileHandleForWritingAtPath:self.cachePath];
// 如果文件不存在，直接寫入數據
if (!fp) {
    [data writeToFile:self.cachePath atomically:YES];
} else {
    // 移動到文件末尾
    [fp seekToEndOfFile];
    // 將數據文件追加到文件末尾
    [fp writeData:data];
    // 關閉文件句柄
    [fp closeFile];
}

檢查文件大小
// 判斷文件是否存在
if ([[NSFileManager defaultManager] fileExistsAtPath:self.cachePath]) {
    NSDictionary *dict = [[NSFileManager defaultManager] attributesOfItemAtPath:self.cachePath error:NULL];
    return [dict[NSFileSize] longLongValue];
} else {
    return 0;
}

提示：由於數據是追加的，為了避免重復從網絡下載文件，在下載之前
判斷緩存路徑中文件是否已經存在
如果存在檢查文件大小
如果文件大小與網絡資源大小一致，則不再下載

全部代碼如下

//
//  MJViewController.m
//  01.文件下載
//
//  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

//
//  FileDownload.m
//  01.文件下載
//
//  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
// 每次下載的字節數
#define kBytesPerTimes  20250

@interface FileDownload()
@property (nonatomic, strong) NSString *cacheFile;
@property (nonatomic, strong) UIImage *cacheImage;
@end

@implementation FileDownload
/**
 為了保證開發的簡單,所有方法都不使用多線程,所有的注意力都保持在文件下載上
 
 在開發中如果碰到比較繞的計算問題時,建議:
 1> 測試數據不要太大
 2> 測試數據的數值變化,能夠用筆算計算出准確的數值
 3> 編寫代碼對照測試

 */
//- (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中的串行隊列異步方法
    dispatch_queue_t q = dispatch_queue_create("cn.itcast.download", DISPATCH_QUEUE_SERIAL);
    
    dispatch_async(q, ^{
        NSLog(@"%@", [NSThread currentThread]);
        
        // 把對URL進行MD5加密之後的結果當成文件名
        self.cacheFile = [url absoluteString];
        
        // 1. 從網絡下載文件,需要知道這個文件的大小
        long long fileSize = [self fileSizeWithURL:url];
        // 計算本地緩存文件大小
        long long cacheFileSize = [self localFileSize];
        
        if (cacheFileSize == fileSize) {
            dispatch_async(dispatch_get_main_queue(), ^{
                completion(self.cacheImage);
            });
            NSLog(@"文件已經存在");
            return;
        }
        
        // 2. 確定每個數據包的大小
        long long fromB = 0;
        long long toB = 0;
        // 計算起始和結束的字節數
        while (fileSize > kBytesPerTimes) {
            // 20480 + 20480
            //
            toB = fromB + kBytesPerTimes - 1;
            
            // 3. 分段下載文件
            [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 下載指定字節范圍的數據包
/**
 NSURLRequestUseProtocolCachePolicy = 0,        // 默認的緩存策略,內存緩存
 
 NSURLRequestReloadIgnoringLocalCacheData = 1,  // 忽略本地的內存緩存
 NSURLRequestReloadIgnoringCacheData
 */
- (void)downloadDataWithURL:(NSURL *)url fromB:(long long)fromB toB:(long long)toB
{
    NSLog(@"數據包:%@", [NSThread currentThread]);
    
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:kTimeOut];
    
    // 指定請求中所要GET的字節范圍
    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];
    
    // 寫入文件,覆蓋文件不會追加
//    [data writeToFile:@"/Users/aplle/Desktop/1.png" atomically:YES];
    [self appendData:data];
    
    NSLog(@"%@", response);
}

#pragma mark - 讀取本地緩存文件大小
- (long long)localFileSize
{
    // 讀取本地文件信息
    NSDictionary *dict = [[NSFileManager defaultManager] attributesOfItemAtPath:self.cacheFile error:NULL];
    NSLog(@"%lld", [dict[NSFileSize] longLongValue]);
    
    return [dict[NSFileSize] longLongValue];
}

#pragma mark - 追加數據到文件
- (void)appendData:(NSData *)data
{
    // 判斷文件是否存在
    NSFileHandle *fp = [NSFileHandle fileHandleForWritingAtPath:self.cacheFile];
    // 如果文件不存在創建文件
    if (!fp) {
        [data writeToFile:self.cacheFile atomically:YES];
    } else {
        // 如果文件已經存在追加文件
        // 1> 移動到文件末尾
        [fp seekToEndOfFile];
        // 2> 追加數據
        [fp writeData:data];
        // 3> 寫入文件
        [fp closeFile];
    }
}

#pragma mark - 獲取網絡文件大小
- (long long)fileSizeWithURL:(NSURL *)url
{
    // 默認是GET
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:0 timeoutInterval:kTimeOut];
    
    // HEAD 頭,只是返回文件資源的信息,不返回具體是數據
    // 如果要獲取資源的MIMEType,也必須用HEAD,否則,數據會被重復下載兩次
    request.HTTPMethod = @"HEAD";

    // 使用同步方法獲取文件大小
    NSURLResponse *response = nil;
    
    [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:NULL];
    
    // expectedContentLength文件在網絡上的大小
    NSLog(@"%lld", response.expectedContentLength);
    
    return response.expectedContentLength;
}

@end

二、文件上傳

代碼如下

//
//  MJViewController.m
//  02.Post上傳
//
//  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:@"頭像1.png" ofType:nil];
    NSData *data = [NSData dataWithContentsOfFile:path];
    
    [upload uploadFileWithURL:[NSURL URLWithString:urlString] data:data];
}

@end

//
//  UploadFile.m
//  02.Post上傳
//
//  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;           // 本次上傳標示字符串
static NSString *uploadID;              // 上傳(php)腳本中，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 - 上傳文件
- (void)uploadFileWithURL:(NSURL *)url data:(NSData *)data
{
    // 1> 數據體
    NSString *topStr = [self topStringWithMimeType:@"image/png" uploadFile:@"頭像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出了作用域就會被釋放,因此不用copy
    request.HTTPBody = dataM;
    
    // 2> 設置Request的頭屬性
    request.HTTPMethod = @"POST";
    
    // 3> 設置Content-Length
    NSString *strLength = [NSString stringWithFormat:@"%ld", (long)dataM.length];
    [request setValue:strLength forHTTPHeaderField:@"Content-Length"];
    
    // 4> 設置Content-Type
    NSString *strContentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", randomIDStr];
    [request setValue:strContentType forHTTPHeaderField:@"Content-Type"];
    
    // 3> 連接服務器發送請求
    [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

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