背景
在iOS端由于文件系统的封闭性，文件的上传变得十分麻烦，一个比较好的解决方案是通过局域网WiFi来传输文件并存储到沙盒中。
简介
SGWiFiUpload是一个基于CocoaHTTPServer的WiFi上传框架。CocoaHTTPServer是一个可运行于iOS和OS X上的轻量级服务端框架，可以处理GET和POST请求，通过对代码的初步改造，实现了iOS端的WiFi文件上传与上传状态监听。
下载与使用
目前已经做成了易用的框架，上传到了GitHub，点击这里进入，欢迎Star！
请求的处理
CocoaHTTPServer通过HTTPConnection这一接口实现类来回调网络请求的各个状态，包括对请求头、响应体的解析等。为了实现文件上传，需要自定义一个继承HTTPConnection的类，这里命名为SGHTTPConnection，与文件上传有关的几个方法如下。
解析文件上传的请求头
- (void)processStartOfPartWithHeader:(MultipartMessageHeader*) header {
// in this sample, we are not interested in parts, other then file parts.
// check content disposition to find out filename
MultipartMessageHeaderField* disposition = [header.fields objectForKey:@"Content-Disposition"];
NSString* filename = [[disposition.params objectForKey:@"filename"] lastPathComponent];
if ( (nil == filename) || [filename isEqualToString: @""] ) {
// it's either not a file part, or
// an empty form sent. we won't handle it.
return;
}
// 这里用于发出文件开始上传的通知
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:SGFileUploadDidStartNotification object:@{@"fileName" : filename ?: @"File"}];
});
// 这里用于设置文件的保存路径，先预存一个空文件，然后进行追加写内容
NSString *uploadDirPath = [SGWiFiUploadManager sharedManager].savePath;
BOOL isDir = YES;
if (![[NSFileManager defaultManager]fileExistsAtPath:uploadDirPath isDirectory:&isDir ]) {
[[NSFileManager defaultManager]createDirectoryAtPath:uploadDirPath withIntermediateDirectories:YES attributes:nil error:nil];
}
NSString* filePath = [uploadDirPath stringByAppendingPathComponent: filename];
if( [[NSFileManager defaultManager] fileExistsAtPath:filePath] ) {
storeFile = nil;
}
else {
HTTPLogVerbose(@"Saving file to %@", filePath);
if(![[NSFileManager defaultManager] createDirectoryAtPath:uploadDirPath withIntermediateDirectories:true attributes:nil error:nil]) {
HTTPLogError(@"Could not create directory at path: %@", filePath);
}
if(![[NSFileManager defaultManager] createFileAtPath:filePath contents:nil attributes:nil]) {
HTTPLogError(@"Could not create file at path: %@", filePath);
}
storeFile = [NSFileHandle fileHandleForWritingAtPath:filePath];
[uploadedFiles addObject: [NSString stringWithFormat:@"/upload/%@", filename]];
}
}其中有中文注释的两处是比较重要的地方，这里根据请求头发出了文件开始上传的通知，并且往要存放的路径写一个空文件，以便后续追加内容。
上传过程中的处理
- (void) processContent:(NSData*) data WithHeader:(MultipartMessageHeader*) header
{
// here we just write the output from parser to the file.
// 由于除去文件内容外，还有HTML内容和空文件通过此方法处理，因此需要过滤掉HTML和空文件内容
if (!header.fields[@"Content-Disposition"]) {
return;
} else {
MultipartMessageHeaderField *field = header.fields[@"Content-Disposition"];
NSString *fileName = field.params[@"filename"];
if (fileName.length == 0) return;
}
self.currentLength += data.length;
CGFloat progress;
if (self.contentLength == 0) {
progress = 1.0f;
} else {
progress = (CGFloat)self.currentLength / self.contentLength;
}
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:SGFileUploadProgressNotification object:@{@"progress" : @(progress)}];
});
if (storeFile) {
[storeFile writeData:data];
}
}这里除了拼接文件内容以外，还发出了上传进度的通知，当前方法中只能拿到这一段文件的长度，总长度需要通过下面的方法拿到。
获取文件大小
- (void)prepareForBodyWithSize:(UInt64)contentLength
{
HTTPLogTrace();
// 设置文件总大小，并初始化当前已经传输的文件大小。
self.contentLength = contentLength;
self.currentLength = 0;
// set up mime parser
NSString* boundary = [request headerField:@"boundary"];
parser = [[MultipartFormDataParser alloc] initWithBoundary:boundary formEncoding:NSUTF8StringEncoding];
parser.delegate = self;
uploadedFiles = [[NSMutableArray alloc] init];
}处理传输完毕
- (void) processEndOfPartWithHeader:(MultipartMessageHeader*) header
{
// as the file part is over, we close the file.
// 由于除去文件内容外，还有HTML内容和空文件通过此方法处理，因此需要过滤掉HTML和空文件内容
if (!header.fields[@"Content-Disposition"]) {
return;
} else {
MultipartMessageHeaderField *field = header.fields[@"Content-Disposition"];
NSString *fileName = field.params[@"filename"];
if (fileName.length == 0) return;
}
[storeFile closeFile];
storeFile = nil;
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:SGFileUploadDidEndNotification object:nil];
});
}这里关闭了文件管道，并且发出了文件上传完毕的通知。
开启Server
CocoaHTTPServer默认的Web根目录为MainBundle，他会在目录下寻找index.html，文件上传的请求地址为upload.html，当以POST方式请求upload.html时，请求会被Server拦截，并且交由HTTPConnection处理。
- (BOOL)startHTTPServerAtPort:(UInt16)port {
HTTPServer *server = [HTTPServer new];
server.port = port;
self.httpServer = server;
[self.httpServer setDocumentRoot:self.webPath];
[self.httpServer setConnectionClass:[SGHTTPConnection class]];
NSError *error = nil;
[self.httpServer start:&error];
return error == nil;
}在HTML中发送POST请求上传文件
在CocoaHTTPServer给出的样例中有用于文件上传的index.html，要实现文件上传，只需要一个POST方法的form表单，action为upload.html，每一个文件使用一个input标签，type为file即可，这里为了美观对input标签进行了自定义。
下面的代码演示了能同时上传3个文件的index.html代码。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<style>
body {
margin: 0px;
padding: 0px;
font-size: 12px;
background-color: rgb(244,244,244);
text-align: center;
}
#container {
margin: auto;
}
#form {
margin-top: 60px;
}
.upload {
margin-top: 2px;
}
#submit input {
background-color: #ea4c88;
color: #eee;
font-weight: bold;
margin-top: 10px;
text-align: center;
font-size: 16px;
border: none;
width: 120px;
height: 36px;
}
#submit input:hover {
background-color: #d44179;
}
#submit input:active {
background-color: #a23351;
}
.uploadField {
margin-top: 2px;
width: 200px;
height: 22px;
font-size: 12px;
}
.uploadButton {
background-color: #ea4c88;
color: #eee;
font-weight: bold;
text-align: center;
font-size: 15px;
border: none;
width: 80px;
height: 26px;
}
.uploadButton:hover {
background-color: #d44179;
}
.uploadButton:active {
background-color: #a23351;
}
</style>
<body>
<div id="container">
<div id="form">
<h2>WiFi File Upload</h2>
<form name="form" action="upload.html" method="post" enctype="multipart/form-data" accept-charset="utf-8">
<div class="upload">
<input type="file" name="upload1" id="upload1" style="display:none" onChange="document.form.path1.value=this.value">
<input class="uploadField" name="path1" readonly>
<input class="uploadButton" type="button" value="Open" onclick="document.form.upload1.click()">
</div>
<div class="upload">
<input type="file" name="upload2" id="upload2" style="display:none" onChange="document.form.path2.value=this.value">
<input class="uploadField" name="path2" readonly>
<input class="uploadButton" type="button" value="Open" onclick="document.form.upload2.click()">
</div>
<div class="upload">
<input type="file" name="upload3" id="upload3" style="display:none" onChange="document.form.path3.value=this.value">
<input class="uploadField" name="path3" readonly>
<input class="uploadButton" type="button" value="Open" onclick="document.form.upload3.click()">
</div>
<div id="submit"><input type="submit" value="Submit"></div>
</form>
</div>
</div>
</body>
</html>表单提交后，会进入upload.html页面，该页面用于说明上传完毕，下面的代码实现了3秒后的重定向返回。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<meta http-equiv=refresh content="3;url=index.html">
</head>
<body>
<h3>Upload Succeeded!</h3>
<p>The Page will be back in 3 seconds</p>
</body>
</html>