【iOS】搭建本地http服务，并实现简单的GET与POST请求

最近的一个项目中，需要向 safari 前端页面传输数据，研究了一番之后发现只有搭建本地http服务才能完美解决这一需求。查询一番资料之后，我决定采用CocoaHttpServer这个现成的轮子。CocoaHttpServer是由deusty designs开源的一个项目，支持异步socket，ipv4和ipv6，http Authentication和TLS加密，小巧玲珑，而且使用方法也非常简单。

开启http服务

首先，我们需要开启http服务，代码如下

    // Configure our logging framework.
    [DDLog addLogger:[DDTTYLogger sharedInstance]];
    
    // Initalize our http server
    httpServer = [[HTTPServer alloc] init];
    
    // Tell the server to broadcast its presence via Bonjour.
    [httpServer setType:@"_http._tcp."];
    
    // Normally there's no need to run our server on any specific port.
    [httpServer setPort:12345];
    
    // We're going to extend the base HTTPConnection class with our MyHTTPConnection class.
    [httpServer setConnectionClass:[YDHTTPConnection class]];
    
    // Serve files from our embedded Web folder
    NSString *webPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"Web"];
    DDLogInfo(@"Setting document root: %@", webPath);
    [httpServer setDocumentRoot:webPath];
    
    NSError *error = nil;
    if(![httpServer start:&error])
    {
        DDLogError(@"Error starting HTTP Server: %@", error);
    }

[httpServer setPort:12345]用来设置端口号，此处可设置成80端口，如果是80端口，访问手机服务器的时候可以不用写端口号了。[httpServer setDocumentRoot:webPath]用来设置服务器根路径。这里要注意我们设置根路径的文件夹在拖进工程时应选择create folder references方式，这样才能在外部浏览器通过路径访问到文件夹内部的文件。

设置GET与POST路径

GET与POST路径的配置是在一个继承自HTTPConnection的类中完成的，即上一步[httpServer setConnectionClass:[YDHTTPConnection class]]中的YDHTTPConnection类。我们要在该类中重写以下方法。

#pragma mark - get & post

- (BOOL)supportsMethod:(NSString *)method atPath:(NSString *)path
{
    HTTPLogTrace();
    
    // Add support for POST
    if ([method isEqualToString:@"POST"])
    {
        if ([path isEqualToString:@"/calculate"])
        {
            // Let's be extra cautious, and make sure the upload isn't 5 gigs
            return YES;
        }
    }
    
    return [super supportsMethod:method atPath:path];
}

- (BOOL)expectsRequestBodyFromMethod:(NSString *)method atPath:(NSString *)path
{
    HTTPLogTrace();
    
    // Inform HTTP server that we expect a body to accompany a POST request
    if([method isEqualToString:@"POST"]) return YES;
    
    return [super expectsRequestBodyFromMethod:method atPath:path];
}

- (NSObject<HTTPResponse> *)httpResponseForMethod:(NSString *)method URI:(NSString *)path
{
    HTTPLogTrace();
    
    //获取idfa
    if ([path isEqualToString:@"/getIdfa"])
    {
        HTTPLogVerbose(@"%@[%p]: postContentLength: %qu", THIS_FILE, self, requestContentLength);
        NSString *idfa = [[[ASIdentifierManager sharedManager] advertisingIdentifier] UUIDString];
        NSData *responseData = [idfa dataUsingEncoding:NSUTF8StringEncoding];
        return [[HTTPDataResponse alloc] initWithData:responseData];
    }
    //加减乘除计算
    if ([method isEqualToString:@"POST"] && [path isEqualToString:@"/calculate"])
    {
        HTTPLogVerbose(@"%@[%p]: postContentLength: %qu", THIS_FILE, self, requestContentLength);
        NSData *requestData = [request body];
        NSDictionary *params = [self getRequestParam:requestData];
        NSInteger firstNum = [params[@"firstNum"] integerValue];
        NSInteger secondNum = [params[@"secondNum"] integerValue];
        NSDictionary *responsDic = @{@"add":@(firstNum + secondNum),
                                     @"sub":@(firstNum - secondNum),
                                     @"mul":@(firstNum * secondNum),
                                     @"div":@(firstNum / secondNum)};
        NSData *responseData = [NSJSONSerialization dataWithJSONObject:responsDic options:0 error:nil];
        return [[HTTPDataResponse alloc] initWithData:responseData];
    }
    
    return [super httpResponseForMethod:method URI:path];
}

- (void)prepareForBodyWithSize:(UInt64)contentLength
{
    HTTPLogTrace();
    
    // If we supported large uploads,
    // we might use this method to create/open files, allocate memory, etc.
}

- (void)processBodyData:(NSData *)postDataChunk
{
    HTTPLogTrace();
    
    // Remember: In order to support LARGE POST uploads, the data is read in chunks.
    // This prevents a 50 MB upload from being stored in RAM.
    // The size of the chunks are limited by the POST_CHUNKSIZE definition.
    // Therefore, this method may be called multiple times for the same POST request.
    
    BOOL result = [request appendData:postDataChunk];
    if (!result)
    {
        HTTPLogError(@"%@[%p]: %@ - Couldn't append bytes!", THIS_FILE, self, THIS_METHOD);
    }
}

#pragma mark - 私有方法

//获取上行参数
- (NSDictionary *)getRequestParam:(NSData *)rawData
{
    if (!rawData) return nil;
    
    NSString *raw = [[NSString alloc] initWithData:rawData encoding:NSUTF8StringEncoding];
    NSMutableDictionary *paramDic = [NSMutableDictionary dictionary];
    NSArray *array = [raw componentsSeparatedByString:@"&"];
    for (NSString *string in array) {
        NSArray *arr = [string componentsSeparatedByString:@"="];
        NSString *value = [arr.lastObject stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
        [paramDic setValue:value forKey:arr.firstObject];
    }
    return [paramDic copy];
}

其中，- (BOOL)supportsMethod:(NSString *)method atPath:(NSString *)path用来配置需要支持的POST路径。父类HTTPConnection中对GET方法是默认支持的，而POST方法则必须通过重写来支持。而- (NSObject<HTTPResponse> *)httpResponseForMethod:(NSString *)method URI:(NSString *)path方法中则用来配置不同方法及路径对应的处理方式及返回数据。

外部访问

屏幕快照 2018-01-28 下午3.41.26.png

当我们的服务启动后，假如要在外部访问上图中的index.html文件，只需通过http://localhost:12345/index.html这样的路径即可。当然，也可以通过http://127.0.0.1:12345/index.html或者将127.0.0.1替换成设备ip。而GET和POST方法我们也可以通过以下前端代码来进行验证。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
    <button onclick="getIdfa()">获取idfa</button>
    <button onclick="calculate()">加减乘除</button>
    
    <script type="text/javascript">
        function getIdfa() {
            $.ajax({
                type: "get",    //请求方式
                async: true,    //是否异步
                url: "http://localhost:12345/getIdfa",
                success: function (data) {
                    alert(data);
                },
                error: function () {
                   alert("error");
                }
            });
        }
        function calculate() {
            $.ajax({
                type: "post",    //请求方式
                async: true,    //是否异步
                url: "http://localhost:12345/calculate",
                data: {"firstNum":9, "secondNum":7},
                success: function (data) {
                    alert(data);
                },
                error: function () {
                    alert("error");
                }
            });
        }
    </script>
</body>
</html>

另外，在h5访问本地服务时，还会存在跨域问题。这个问题我们需要通过在HTTPConnection类的- (NSData *)preprocessResponse:(HTTPMessage *)response和- (NSData *)preprocessErrorResponse:(HTTPMessage *)response方法中加入以下代码来解决。

//允许跨域访问
[response setHeaderField:@"Access-Control-Allow-Origin" value:@"*"];
[response setHeaderField:@"Access-Control-Allow-Headers" value:@"X-Requested-With"];
[response setHeaderField:@"Access-Control-Allow-Methods" value:@"PUT,POST,GET,DELETE,OPTIONS"];

后台运行

我们都知道，苹果对APP占用硬件资源管理的很严格，更不要说应用在后台运行时的资源占用了。正常情况下，使用应用时，APP从硬盘加载到内存后，便开始正常工作。当用户按下home键，APP便被挂起到后台。当内存不够用时，系统会自动把之前挂起状态下的APP从内存中清除。如果要使程序在后台常驻，则需要申请后台权限。

因此，我们要想保持本地服务在后台运行，便必须要保证APP拥有后台运行的权限，并需要根据APP的具体类型（如：音乐播放、定位、VOIP等）在 Capabilities 中添加相应的 Background Modes 键值对，如下图所示

屏幕快照 2018-06-26 下午4.54.54.png

同时需要在代理方法中添加下述代码。当然，如果你的APP不存在和Background Modes 相符合的功能的话，这么做可能会导致 AppStore 审核不通过。

- (void)applicationDidEnterBackground:(UIApplication *)application {
    _bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
        [application endBackgroundTask:_bgTask];
        _bgTask = UIBackgroundTaskInvalid;
    }];
}

配置https

利用 CocoaHttpServer 也可以搭建出https服务。只需要在YDHTTPConnection中重写以下两个方法。

#pragma mark - https

- (BOOL)isSecureServer
{
    HTTPLogTrace();

    return YES;
}

- (NSArray *)sslIdentityAndCertificates
{
    HTTPLogTrace();
    
    SecIdentityRef identityRef = NULL;
    SecCertificateRef certificateRef = NULL;
    SecTrustRef trustRef = NULL;
    NSString *thePath = [[NSBundle mainBundle] pathForResource:@"localhost" ofType:@"p12"];
    NSData *PKCS12Data = [[NSData alloc] initWithContentsOfFile:thePath];
    CFDataRef inPKCS12Data = (__bridge CFDataRef)PKCS12Data;
    CFStringRef password = CFSTR("123456");
    const void *keys[] = { kSecImportExportPassphrase };
    const void *values[] = { password };
    CFDictionaryRef optionsDictionary = CFDictionaryCreate(NULL, keys, values, 1, NULL, NULL);
    CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);

    OSStatus securityError = errSecSuccess;
    securityError =  SecPKCS12Import(inPKCS12Data, optionsDictionary, &items);
    if (securityError == 0) {
        CFDictionaryRef myIdentityAndTrust = CFArrayGetValueAtIndex (items, 0);
        const void *tempIdentity = NULL;
        tempIdentity = CFDictionaryGetValue (myIdentityAndTrust, kSecImportItemIdentity);
        identityRef = (SecIdentityRef)tempIdentity;
        const void *tempTrust = NULL;
        tempTrust = CFDictionaryGetValue (myIdentityAndTrust, kSecImportItemTrust);
        trustRef = (SecTrustRef)tempTrust;
    } else {
        NSLog(@"Failed with error code %d",(int)securityError);
        return nil;
    }

    SecIdentityCopyCertificate(identityRef, &certificateRef);
    NSArray *result = [[NSArray alloc] initWithObjects:(__bridge id)identityRef, (__bridge id)certificateRef, nil];

    return result;
}

在实验过程中我使用的为自签名SSL证书，因此访问文件时会出现弹框提示不安全的问题，而GET与POST接口也出现了访问失败的情况。目前我想到的解决方案是将一个域名和127.0.0.1进行绑定，并使用该域名的SSL证书替换自签名证书。至于可行性，还没有做过实验，如果各位读者有更好的想法，欢迎一起讨论。

本文相关demo下载欢迎到我的github：Github地址