YYViewController.m
#import "YYViewController.h"

#define YYEncode(str) [str dataUsingEncoding:NSUTF8StringEncoding]

@interface YYViewController ()

@end

@implementation YYViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)upload:(NSString *)name filename:(NSString *)filename mimeType:(NSString *)mimeType data:(NSData *)data parmas:(NSDictionary *)params
{
    // 文件上傳
    NSURL *url = [NSURL URLWithString:@"http://192.168.1.200:8080/YYServer/upload"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    request.HTTPMethod = @"POST";
   
    // 設(shè)置請求體
    NSMutableData *body = [NSMutableData data];
   
    /***************文件參數(shù)***************/
    // 參數(shù)開始的標(biāo)志
    [body appendData:YYEncode(@"--YY\r\n")];
    // name : 指定參數(shù)名(必須跟服務(wù)器端保持一致)
    // filename : 文件名
    NSString *disposition = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"; filename=\"%@\"\r\n", name, filename];
    [body appendData:YYEncode(disposition)];
    NSString *type = [NSString stringWithFormat:@"Content-Type: %@\r\n", mimeType];
    [body appendData:YYEncode(type)];
   
    [body appendData:YYEncode(@"\r\n")];
    [body appendData:data];
    [body appendData:YYEncode(@"\r\n")];
   
    /***************普通參數(shù)***************/
    [params enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        // 參數(shù)開始的標(biāo)志
        [body appendData:YYEncode(@"--YY\r\n")];
        NSString *disposition = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n", key];
        [body appendData:YYEncode(disposition)];

        [body appendData:YYEncode(@"\r\n")];
        [body appendData:YYEncode(obj)];
        [body appendData:YYEncode(@"\r\n")];
    }];
   
    /***************參數(shù)結(jié)束***************/
    // YY--\r\n
    [body appendData:YYEncode(@"--YY--\r\n")];
    request.HTTPBody = body;
   
    // 設(shè)置請求頭
    // 請求體的長度
    [request setValue:[NSString stringWithFormat:@"%zd", body.length] forHTTPHeaderField:@"Content-Length"];
    // 聲明這個(gè)POST請求是個(gè)文件上傳
    [request setValue:@"multipart/form-data; boundary=YY" forHTTPHeaderField:@"Content-Type"];
   
    // 發(fā)送請求
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
        if (data) {
            NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:nil];
            NSLog(@"%@", dict);
        } else {
            NSLog(@"上傳失敗");
        }
    }];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    // Socket 實(shí)現(xiàn)斷點(diǎn)上傳
   
    //apache-tomcat-6.0.41/conf/web.xml 查找 文件的 mimeType
//    UIImage *image = [UIImage imageNamed:@"test"];
//    NSData *filedata = UIImagePNGRepresentation(image);
//    [self upload:@"file" filename:@"test.png" mimeType:@"image/png" data:filedata parmas:@{@"username" : @"123"}];
   
    // 給本地文件發(fā)送一個(gè)請求
    NSURL *fileurl = [[NSBundle mainBundle] URLForResource:@"itcast.txt" withExtension:nil];
    NSURLRequest *request = [NSURLRequest requestWithURL:fileurl];
    NSURLResponse *repsonse = nil;
    NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&repsonse error:nil];
   
    // 得到mimeType
    NSLog(@"%@", repsonse.MIMEType);
    [self upload:@"file" filename:@"itcast.txt" mimeType:repsonse.MIMEType data:data parmas:@{
                                                                                              @"username" : @"999",
                                                                                              @"type" : @"XML"}];
}

@end

#import "YYViewController.h"
#import "YYFileMultiDownloader.h"

@interface YYViewController ()
@property (nonatomic, strong) YYFileMultiDownloader *fileMultiDownloader;
@end

@implementation YYViewController
-  (YYFileMultiDownloader *)fileMultiDownloader
{
    if (!_fileMultiDownloader) {
        _fileMultiDownloader = [[YYFileMultiDownloader alloc] init];
        // 需要下載的文件遠(yuǎn)程URL
        _fileMultiDownloader.url = @"http://192.168.1.200:8080/MJServer/resources/jre.zip";
        // 文件保存到什么地方
        NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
        NSString *filepath = [caches stringByAppendingPathComponent:@"jre.zip"];
        _fileMultiDownloader.destPath = filepath;
    }
    return _fileMultiDownloader;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
   
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self.fileMultiDownloader start];
}

@end

YYFileDownloader.h文件
#import <Foundation/Foundation.h>

@interface YYFileDownloader : NSObject
{
    BOOL _downloading;
}
/**
 * 所需要下載文件的遠(yuǎn)程URL(連接服務(wù)器的路徑)
 */
@property (nonatomic, copy) NSString *url;
/**
 * 文件的存儲路徑(文件下載到什么地方)
 */
@property (nonatomic, copy) NSString *destPath;

/**
 * 是否正在下載(有沒有在下載, 只有下載器內(nèi)部才知道)
 */
@property (nonatomic, readonly, getter = isDownloading) BOOL downloading;

/**
 * 用來監(jiān)聽下載進(jìn)度
 */
@property (nonatomic, copy) void (^progressHandler)(double progress);

/**
 * 開始(恢復(fù))下載
 */
- (void)start;

/**
 * 暫停下載
 */
- (void)pause;
@end

#import "YYFileDownloader.h"

@implementation YYFileDownloader
@end

#import "YYFileDownloader.h"

@interface YYFileSingleDownloader : YYFileDownloader
/**
 *  開始的位置
 */
@property (nonatomic, assign) long long begin;
/**
 *  結(jié)束的位置
 */
@property (nonatomic, assign) long long end;
@end

#import "YYFileSingleDownloader.h"
@interface YYFileSingleDownloader() <NSURLConnectionDataDelegate>
/**
 * 連接對象
 */
@property (nonatomic, strong) NSURLConnection *conn;

/**
 *  寫數(shù)據(jù)的文件句柄
 */
@property (nonatomic, strong) NSFileHandle *writeHandle;
/**
 *  當(dāng)前已下載數(shù)據(jù)的長度
 */
@property (nonatomic, assign) long long currentLength;
@end

@implementation YYFileSingleDownloader

- (NSFileHandle *)writeHandle
{
    if (!_writeHandle) {
        _writeHandle = [NSFileHandle fileHandleForWritingAtPath:self.destPath];
    }
    return _writeHandle;
}

/**
 * 開始(恢復(fù))下載
 */
- (void)start
{
    NSURL *url = [NSURL URLWithString:self.url];
    // 默認(rèn)就是GET請求
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    // 設(shè)置請求頭信息
    NSString *value = [NSString stringWithFormat:@"bytes=%lld-%lld", self.begin + self.currentLength, self.end];
    [request setValue:value forHTTPHeaderField:@"Range"];
    self.conn = [NSURLConnection connectionWithRequest:request delegate:self];
   
    _downloading = YES;
}

/**
 * 暫停下載
 */
- (void)pause
{
    [self.conn cancel];
    self.conn = nil;
   
    _downloading = NO;
}

#pragma mark - NSURLConnectionDataDelegate 代理方法
/**
 *  1. 當(dāng)接受到服務(wù)器的響應(yīng)(連通了服務(wù)器)就會調(diào)用
 */
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
   
}

/**
 *  2. 當(dāng)接受到服務(wù)器的數(shù)據(jù)就會調(diào)用(可能會被調(diào)用多次, 每次調(diào)用只會傳遞部分?jǐn)?shù)據(jù))
 */
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    // 移動到文件的尾部
    [self.writeHandle seekToFileOffset:self.begin + self.currentLength];
    // 從當(dāng)前移動的位置(文件尾部)開始寫入數(shù)據(jù)
    [self.writeHandle writeData:data];
   
    // 累加長度
    self.currentLength += data.length;
   
    // 打印下載進(jìn)度
    double progress = (double)self.currentLength / (self.end - self.begin);
    if (self.progressHandler) {
        self.progressHandler(progress);
    }
}

/**
 *  3. 當(dāng)服務(wù)器的數(shù)據(jù)接受完畢后就會調(diào)用
 */
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    // 清空屬性值
    self.currentLength = 0;
   
    // 關(guān)閉連接(不再輸入數(shù)據(jù)到文件中)
    [self.writeHandle closeFile];
    self.writeHandle = nil;
}

/**
 *  請求錯(cuò)誤(失敗)的時(shí)候調(diào)用(請求超時(shí)\斷網(wǎng)\沒有網(wǎng), 一般指客戶端錯(cuò)誤)
 */
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
   
}

@end

#import "YYFileDownloader.h"

@interface YYFileMultiDownloader : YYFileDownloader
 
@end

#import "YYFileMultiDownloader.h"
#import "YYFileSingleDownloader.h"

#define YYMaxDownloadCount 4

@interface YYFileMultiDownloader()
@property (nonatomic, strong) NSMutableArray *singleDownloaders;
@property (nonatomic, assign) long long totalLength;
@end

@implementation YYFileMultiDownloader

- (void)getFilesize
{
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:self.url]];
    request.HTTPMethod = @"HEAD";
   
    NSURLResponse *response = nil;
#warning 這里要用異步請求
    [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];
    self.totalLength = response.expectedContentLength;
}

- (NSMutableArray *)singleDownloaders
{
    if (!_singleDownloaders) {
        _singleDownloaders = [NSMutableArray array];
       
        // 獲得文件大小
        [self getFilesize];
       
        // 每條路徑的下載量
        long long size = 0;
        if (self.totalLength % YYMaxDownloadCount == 0) {
            size = self.totalLength / YYMaxDownloadCount;
        } else {
            size = self.totalLength / YYMaxDownloadCount + 1;
        }
       
        // 創(chuàng)建N個(gè)下載器
        for (int i = 0; i<YYMaxDownloadCount; i++) {
            YYFileSingleDownloader *singleDownloader = [[YYFileSingleDownloader alloc] init];
            singleDownloader.url = self.url;
            singleDownloader.destPath = self.destPath;
            singleDownloader.begin = i * size;
            singleDownloader.end = singleDownloader.begin + size - 1;
            singleDownloader.progressHandler = ^(double progress){
                NSLog(@"%d --- %f", i, progress);
            };
            [_singleDownloaders addObject:singleDownloader];
        }
       
        // 創(chuàng)建一個(gè)跟服務(wù)器文件等大小的臨時(shí)文件
        [[NSFileManager defaultManager] createFileAtPath:self.destPath contents:nil attributes:nil];
       
        // 讓self.destPath文件的長度是self.totalLengt
        NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:self.destPath];
        [handle truncateFileAtOffset:self.totalLength];
    }
    return _singleDownloaders;
}

/**
 * 開始(恢復(fù))下載
 */
- (void)start
{
    [self.singleDownloaders makeObjectsPerformSelector:@selector(start)];
   
    _downloading = YES;
}

/**
 * 暫停下載
 */
- (void)pause
{
    [self.singleDownloaders makeObjectsPerformSelector:@selector(pause)];
    _downloading = NO;
}

@end