iOS开发中文件的上传和下载功能的基本实现

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

@interface YYViewController ()

@end

- (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
{
    // 文件上传
    NSURL *url = [NSURL URLWithString:@"http://192.168.1.200:8080/YYServer/upload"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    request.HTTPMethod = @"POST";
   
    // 设置请求体
    NSMutableData *body = [NSMutableData data];
   
    /***************文件参数***************/
    // 参数开始的标志
    [body appendData:YYEncode(@"--YYrn")];
    // name : 指定参数名(必须跟服务器端保持一致)
    // filename : 文件名
    NSString *disposition = [NSString stringWithFormat:@"Content-Disposition: form-data; name="%@"; filename="%@"rn", name, filename];
    [body appendData:YYEncode(disposition)];
    NSString *type = [NSString stringWithFormat:@"Content-Type: %@rn", mimeType];
    [body appendData:YYEncode(type)];
   
    [body appendData:YYEncode(@"rn")];
    [body appendData:data];
    [body appendData:YYEncode(@"rn")];
   
    /***************普通参数***************/
    [params enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        // 参数开始的标志
        [body appendData:YYEncode(@"--YYrn")];
        NSString *disposition = [NSString stringWithFormat:@"Content-Disposition: form-data; name="%@"rn", key];
        [body appendData:YYEncode(disposition)];

        [body appendData:YYEncode(@"rn")];
        [body appendData:YYEncode(obj)];
        [body appendData:YYEncode(@"rn")];
    }];
   
    /***************参数结束***************/
    // YY--rn
    [body appendData:YYEncode(@"--YY--rn")];
    request.HTTPBody = body;
   
    // 设置请求头
    // 请求体的长度
    [request setValue:[NSString stringWithFormat:@"%zd", body.length] forHTTPHeaderField:@"Content-Length"];
    // 声明这个POST请求是个文件上传
    [request setValue:@"multipart/form-data; boundary=YY" forHTTPHeaderField:@"Content-Type"];
   
    // 发送请求
    [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(@"上传失败");
        }
    }];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    // Socket 实现断点上传
   
    //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"}];
   
    // 给本地文件发送一个请求
    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

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

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

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

@end

@interface YYFileDownloader : NSObject
{
    BOOL _downloading;
}
/**
 * 所需要下载文件的远程URL(连接服务器的路径)
 */
@property (nonatomic, copy) NSString *url;
/**
 * 文件的存储路径(文件下载到什么地方)
 */
@property (nonatomic, copy) NSString *destPath;

/**
 * 是否正在下载(有没有在下载, 只有下载器内部才知道)
 */
@property (nonatomic, readonly, getter = isDownloading) BOOL downloading;

/**
 * 用来监听下载进度
 */
@property (nonatomic, copy) void (^progressHandler)(double progress);

/**
 * 开始(恢复)下载
 */
- (void)start;

/**
 * 暂停下载
 */
- (void)pause;
@end

@implementation YYFileDownloader
@end

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

/**
 *  写数据的文件句柄
 */
@property (nonatomic, strong) NSFileHandle *writeHandle;
/**
 *  当前已下载数据的长度
 */
@property (nonatomic, assign) long long currentLength;
@end

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

/**
 * 开始(恢复)下载
 */
- (void)start
{
    NSURL *url = [NSURL URLWithString:self.url];
    // 默认就是GET请求
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    // 设置请求头信息
    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;
}

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

#pragma mark - NSURLConnectionDataDelegate 代理方法
/**
 *  1. 当接受到服务器的响应(连通了服务器)就会调用
 */
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
   
}

/**
 *  2. 当接受到服务器的数据就会调用(可能会被调用多次, 每次调用只会传递部分数据)
 */
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    // 移动到文件的尾部
    [self.writeHandle seekToFileOffset:self.begin + self.currentLength];
    // 从当前移动的位置(文件尾部)开始写入数据
    [self.writeHandle writeData:data];
   
    // 累加长度
    self.currentLength += data.length;
   
    // 打印下载进度
    double progress = (double)self.currentLength / (self.end - self.begin);
    if (self.progressHandler) {
        self.progressHandler(progress);
    }
}

/**
 *  3. 当服务器的数据接受完毕后就会调用
 */
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    // 清空属性值
    self.currentLength = 0;
   
    // 关闭连接(不再输入数据到文件中)
    [self.writeHandle closeFile];
    self.writeHandle = nil;
}

/**
 *  请求错误(失败)的时候调用(请求超时断网没有网, 一般指客户端错误)
 */
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
   
}

@end

@interface YYFileMultiDownloader : YYFileDownloader
 
@end

#define YYMaxDownloadCount 4

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

- (void)getFilesize
{
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:self.url]];
    request.HTTPMethod = @"HEAD";
   
    NSURLResponse *response = nil;
#warning 这里要用异步请求
    [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];
    self.totalLength = response.expectedContentLength;
}

- (NSMutableArray *)singleDownloaders
{
    if (!_singleDownloaders) {
        _singleDownloaders = [NSMutableArray array];
       
        // 获得文件大小
        [self getFilesize];
       
        // 每条路径的下载量
        long long size = 0;
        if (self.totalLength % YYMaxDownloadCount == 0) {
            size = self.totalLength / YYMaxDownloadCount;
        } else {
            size = self.totalLength / YYMaxDownloadCount + 1;
        }
       
        // 创建N个下载器
        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];
        }
       
        // 创建一个跟服务器文件等大小的临时文件
        [[NSFileManager defaultManager] createFileAtPath:self.destPath contents:nil attributes:nil];
       
        // 让self.destPath文件的长度是self.totalLengt
        NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:self.destPath];
        [handle truncateFileAtOffset:self.totalLength];
    }
    return _singleDownloaders;
}

/**
 * 开始(恢复)下载
 */
- (void)start
{
    [self.singleDownloaders makeObjectsPerformSelector:@selector(start)];
   
    _downloading = YES;
}

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

@end