关于WKWebView的post请求丢失body问题的解决方案

WKWebView的优点这里不做过多介绍,主要说一下最近解决WKWebView的post请求丢失body问题的解决方案。
WKWebView 通过loadrequest方法加载Post请求会丢失请求体(body)中的内容,进而导致服务器拿不到body中的内容的问题的发生。这个问题的产生主要是因为WKWebView的网络请求的进程与APP不是同一个进程,所以网络请求的过程是这样的:
由APP所在的进程发起request,然后通过IPC通信(进程间通信)将请求的相关信息(请求头、请求行、请求体等)传递给webkit网络线进程接收包装,进行数据的HTTP请求,最终再进行IPC的通信回传给APP所在的进程的。这里如果发起的request请求是post请求的话,由于要进行IPC数据传递,传递的请求体body中根据系统调度,将其舍弃,最终在WKWebView网络进程接受的时候请求体body中的内容变成了空,导致此种情况下的服务器获取不到请求体,导致问题的产生。
为了能够获取POST方法请求之后的body内容,这两天整理了一些解决方案,大致分为三种:

  1. 将网络请求交由Js发起,绕开系统WKWebView的网络的进程请求达到正常请求的目的

  2. 改变POST请求的方法为GET方法(有风险,不一定服务器会接受GET方法)

  3. 将Post请求的请求body内容放入请求的Header中,并通过URLProtocol拦截自定义协议,在拦截中通过NSConnection进行重新请求(重新包装请求body),然后通过回调Client客户端来传递数据内容

三种方法中,我采用了第三种方案,这里说一下第三种方案的实现方式,大致分为三步:

  1. 注册拦截的自定义的scheme

  2. 重写loadRequest()方法,根据request的method方法是否为POST进行URL的拦截替换

  3. 在URLProtocol中进行request的重新包装(获取请求的body内容),使用NSURLConnection进行HTTP请求并将数据回传

这里说明一下为什么要自己去注册自定义的scheme,而不是直接拦截https/http。主要原因是:如果注册了https/http的拦截,那么所有的http(s)请求都会交由系统进程处理,那么此时系统进程会通过IPC的形式传递给实现URLProctol协议的类去处理,在通过IPC传递的过程中丢失body体(上面有讲到),所以在拦截的时候是拿不到POST方法的请求体body的。然而并不是所有的http请求都会走loadrequest()方法(比如js中的ajax请求),所以导致一些POST请求没有被包装(将请求体body内容放到请求头header)就被拦截了,进而丢失请求体body内容,问题一样会产生。所以为了避免这样的问题,我们需要自己去定一个scheme协议,保证不过度拦截并且能够处理我们需要处理的POST请求内容。

以下是具体的实现方式:

  • 注册拦截的自定义的scheme

[NSURLProtocol registerClass:NSClassFromString(@“GCURLProtocol")];
[NSURLProtocol wk_registerScheme:@"gc"];
[NSURLProtocol wk_registerScheme:WkCustomHttp];
[NSURLProtocol wk_registerScheme:WkCustomHttps];
  • 重写loadRequest()方法,根据request的method方法是否为POST进行URL的拦截替换

//包装请求头内容
- (WKNavigation *)loadRequest:(NSURLRequest *)request{
NSLog(@"发起请求:%@ method:%@",request.URL.absoluteString,request.HTTPMethod);
NSMutableURLRequest *mutableRequest = [request mutableCopy];
NSMutableDictionary *requestHeaders = [request.allHTTPHeaderFields mutableCopy];
//判断是否是POST请求,POST请求需要包装request中的body内容到请求头中(会有丢失body问题的产生)
//,包装完成之后重定向到拦截的协议中自己包装处理请求数据内容,拦截协议是GCURLProtocol,请自行搜索
if ([mutableRequest.HTTPMethod isEqualToString:@"POST"] && ([mutableRequest.URL.scheme isEqualToString:@"http"] || [mutableRequest.URL.scheme isEqualToString:@"https"])) {
NSString *absoluteStr = mutableRequest.URL.absoluteString;
if ([[absoluteStr substringWithRange:NSMakeRange(absoluteStr.length-1, 1)] isEqualToString:@"/"]) {
absoluteStr = [absoluteStr stringByReplacingCharactersInRange:NSMakeRange(absoluteStr.length-1, 1) withString:@""];
}

if ([mutableRequest.URL.scheme isEqualToString:@"https"]) {
absoluteStr = [absoluteStr stringByReplacingOccurrencesOfString:@"https" withString:WkCustomHttps];
}else{
absoluteStr = [absoluteStr stringByReplacingOccurrencesOfString:@"http" withString:WkCustomHttp];
}

mutableRequest.URL = [NSURL URLWithString:absoluteStr];
NSString *bodyDataStr = [[NSString alloc]initWithData:mutableRequest.HTTPBody encoding:NSUTF8StringEncoding];
[requestHeaders addEntriesFromDictionary:@{@"httpbody":bodyDataStr}];
mutableRequest.allHTTPHeaderFields = requestHeaders;

NSLog(@"当前请求为POST请求Header:%@",mutableRequest.allHTTPHeaderFields);

}
return [super loadRequest:mutableRequest];
}
  • 在URLProtocol中进行request的重新包装(获取请求的body内容),使用NSURLConnection进行HTTP请求并将数据回传(以下是主要代码)

+ (BOOL)canInitWithRequest:(NSURLRequest *)request {

NSString *scheme = request.URL.scheme;

if ([scheme isEqualToString:InterceptionSchemeKey]){

if ([self propertyForKey:HaveDealRequest inRequest:request]) {
NSLog(@"已经处理,放行");
return NO;
}
return YES;
}

if ([scheme isEqualToString:WkCustomHttp]){

if ([self propertyForKey:HaveDealWkHttpPostBody inRequest:request]) {
NSLog(@"已经处理,放行");
return NO;
}
return YES;
}

if ([scheme isEqualToString:WkCustomHttps]){

if ([self propertyForKey:HaveDealWkHttpsPostBody inRequest:request]) {
NSLog(@"已经处理,放行");
return NO;
}
return YES;
}

return NO;

}
- (void)startLoading {

//截获 gc 链接的所有请求,替换成本地资源或者线上资源
if ([self.request.URL.scheme isEqualToString:InterceptionSchemeKey]) {
[self htmlCacheRequstLoad];
}

else if ([self.request.URL.scheme isEqualToString:WkCustomHttp] || [self.request.URL.scheme isEqualToString:WkCustomHttps]){
[self postBodyAddLoad];
}
else{
NSMutableURLRequest *newRequest = [self cloneRequest:self.request];
NSString *urlString = newRequest.URL.absoluteString;
[self addHttpPostBody:newRequest];
[NSURLProtocol setProperty:@YES forKey:GCProtocolKey inRequest:newRequest];
[self sendRequest:newRequest];
}


}

- (void)addHttpPostBody:(NSMutableURLRequest *)redirectRequest{

//判断当前的请求是否是Post请求
if ([self.request.HTTPMethod isEqualToString:@"POST"]) {
NSLog(@"post请求");
NSMutableDictionary *headerDict = [redirectRequest.allHTTPHeaderFields mutableCopy];
NSString *body = headerDict[@"httpbody"]?:@"";
if (body.length) {
redirectRequest.HTTPBody = [body dataUsingEncoding:NSUTF8StringEncoding];
NSLog(@"body:%@",body);
}
}
}
- (void)postBodyAddLoad{

NSMutableURLRequest *cloneRequest = [self cloneRequest:self.request];
if ([cloneRequest.URL.scheme isEqualToString:WkCustomHttps]) {
cloneRequest.URL = [NSURL URLWithString:[cloneRequest.URL.absoluteString stringByReplacingOccurrencesOfString:WkCustomHttps withString:@"https"]];
[NSURLProtocol setProperty:@YES forKey:HaveDealWkHttpsPostBody inRequest:cloneRequest];
}else if ([cloneRequest.URL.scheme isEqualToString:WkCustomHttp]){

cloneRequest.URL = [NSURL URLWithString:[cloneRequest.URL.absoluteString stringByReplacingOccurrencesOfString:WkCustomHttp withString:@"http"]];
[NSURLProtocol setProperty:@YES forKey:HaveDealWkHttpPostBody inRequest:cloneRequest];
}
//添加body内容
[self addHttpPostBody:cloneRequest];
NSLog(@"请求body添加完成:%@",[[NSString alloc]initWithData:cloneRequest.HTTPBody encoding:NSUTF8StringEncoding]);
[self sendRequest:cloneRequest];

}
//复制Request对象
- (NSMutableURLRequest *)cloneRequest:(NSURLRequest *)request
{
NSMutableURLRequest *newRequest = [NSMutableURLRequest requestWithURL:request.URL cachePolicy:request.cachePolicy timeoutInterval:request.timeoutInterval];

newRequest.allHTTPHeaderFields = request.allHTTPHeaderFields;
[newRequest setValue:@"image/webp,image/*;q=0.8" forHTTPHeaderField:@"Accept"];

if (request.HTTPMethod) {
newRequest.HTTPMethod = request.HTTPMethod;
}

if (request.HTTPBodyStream) {
newRequest.HTTPBodyStream = request.HTTPBodyStream;
}

if (request.HTTPBody) {
newRequest.HTTPBody = request.HTTPBody;
}

newRequest.HTTPShouldUsePipelining = request.HTTPShouldUsePipelining;
newRequest.mainDocumentURL = request.mainDocumentURL;
newRequest.networkServiceType = request.networkServiceType;

return newRequest;
}

#pragma mark - NSURLConnectionDataDelegate
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
/**
* 收到服务器响应
*/
NSURLResponse *returnResponse = response;
[self.client URLProtocol:self didReceiveResponse:returnResponse cacheStoragePolicy:NSURLCacheStorageAllowed];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
/**
* 接收数据
*/
if (!self.recData) {
self.recData = [NSMutableData new];
}
if (data) {
[self.recData appendData:data];
}
}
- (nullable NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(nullable NSURLResponse *)response
{
/**
* 重定向
*/
if (response) {
[self.client URLProtocol:self wasRedirectedToRequest:request redirectResponse:response];
}
return request;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
[self.client URLProtocolDidFinishLoading:self];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
/**
* 加载失败
*/
[self.client URLProtocol:self didFailWithError:error];
}

转自:https://www.jianshu.com/p/4dfc80ca7db2

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