iOS-上傳和下載功能的實現(xiàn)

2020-02-19 15:52:51

字體：大中小

供稿：網(wǎng)友

在iOS開發(fā)中經(jīng)常使用上傳和下載文件的這個功能，對于初級程序員來說可能比較難實現(xiàn)，今天這邊文章是武林技術(shù)頻道小編為大家整理的關(guān)于iOS-上傳和下載功能的實現(xiàn)，一起來了解一下吧！

文件的上傳

說明：文件上傳使用的時POST請求，通常把要上傳的數(shù)據(jù)保存在請求體中。本文介紹如何不借助第三方框架實現(xiàn)iOS開發(fā)中得文件上傳。

　　由于過程較為復(fù)雜，因此本文只貼出部分關(guān)鍵代碼。

主控制器的關(guān)鍵代碼：

復(fù)制代碼代碼如下:

YYViewController.m
#import "YYViewController.h"

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

@interface YYViewController ()

@end

復(fù)制代碼代碼如下:

@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POST請求是個文件上傳
??? [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 實現(xiàn)斷點上傳
???
??? //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

補充說明：

文件上傳請求數(shù)據(jù)格式

2015111091114601.png (654×353)

部分文件的MIMEType

2015111091158899.png (652×361)

多線程斷點下載
說明：本文介紹多線程斷點下載。項目中使用了蘋果自帶的類，實現(xiàn)了同時開啟多條線程下載一個較大的文件。因為實現(xiàn)過程較為復(fù)雜，所以下面貼出完整的代碼。

實現(xiàn)思路：下載開始，創(chuàng)建一個和要下載的文件大小相同的文件（如果要下載的文件為100M，那么就在沙盒中創(chuàng)建一個100M的文件，然后計算每一段的下載量，開啟多條線程下載各段的數(shù)據(jù)，分別寫入對應(yīng)的文件部分）。

2015111091217169.png (305×260)

項目中用到的主要類如下：

2015111091236903.png (218×208)

完成的實現(xiàn)代碼如下：

主控制器中的代碼：

復(fù)制代碼代碼如下:

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

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

復(fù)制代碼代碼如下:

@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

自定義一個基類

復(fù)制代碼代碼如下:

YYFileDownloader.h文件
#import

@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

YYFileDownloader.m文件

復(fù)制代碼代碼如下:

#import "YYFileDownloader.h"

@implementation YYFileDownloader
@end

下載器類繼承自YYFileDownloader這個類

YYFileSingDownloader.h文件

復(fù)制代碼代碼如下:

#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

YYFileSingDownloader.m文件

復(fù)制代碼代碼如下:

#import "YYFileSingleDownloader.h"
@interface YYFileSingleDownloader()
/**
?* 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

復(fù)制代碼代碼如下:

@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;
}

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

@end

設(shè)計多線程下載器(利用HMFileMultiDownloader能開啟多個線程同時下載一個文件)

一個多線程下載器只下載一個文件

YYFileMultiDownloader.h文件

復(fù)制代碼代碼如下:

#import "YYFileDownloader.h"

@interface YYFileMultiDownloader : YYFileDownloader
?
@end

YYFileMultiDownloader.m文件

復(fù)制代碼代碼如下:

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

#define YYMaxDownloadCount 4

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

復(fù)制代碼代碼如下:

@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個下載器
??????? for (int i = 0; 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)建一個跟服務(wù)器文件等大小的臨時文件
??????? [[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;
}