拦截来自 WebView Flash 插件的 Web 请求

Question

我有一个桌面浏览器应用程序，它使用 WebView 来托管 Flash 插件。 Flash 插件会定期向外部网站请求新数据，然后将其绘制为精美的图形。

我想拦截这些网络请求并获取数据（这样我就可以通过 Growl 显示它，而不是保留桌面窗口）。但我可以说，Flash 发出的请求不会被普通的 WebView 代表接收。

还有其他地方可以设置钩子吗？我尝试通过 [NSURLCache setSharedURLCache] 安装自定义 NSURLCache，但从未被调用。我还尝试了调配其他一些类（如 NSCachedURLResponse）的方法，但找不到方法。有什么想法吗？非常感谢！

Answer 1

很惊讶没有人回答这个问题，这实际上很容易。创建NSURLProtocol的子类，然后调用registerClass开始拦截。

[NSURLProtocol registerClass:[MyCustomURLProtocol class]];

以下是子类的重要部分：

#define REQUEST_HEADER_TAG  @"x-mycustomurl-intercept"

+ (BOOL)canInitWithRequest:(NSURLRequest*)theRequest
{
    // Check for the custom header on the request to break the 
    // infinite loop created by the [startLoading] below.
    if ([theRequest valueForHTTPHeaderField:REQUEST_HEADER_TAG]) {
        return NO;
    }

    if ([theRequest.URL.scheme caseInsensitiveCompare:@"http"] == NSOrderedSame) {
        return YES;
    }
    return NO;
}

+ (NSURLRequest*)canonicalRequestForRequest:(NSURLRequest*)theRequest
{
    return theRequest;
}

- (id)initWithRequest:(NSURLRequest*)theRequest
       cachedResponse:(NSCachedURLResponse*)cachedResponse
               client:(id<NSURLProtocolClient>)client
{
    // Add a custom header on the request to break the 
    // infinite loop created by the [startLoading] below.
    NSMutableURLRequest* newRequest = [theRequest mutableCopy];
    [newRequest setValue:@"" forHTTPHeaderField:REQUEST_HEADER_TAG];

    // Now continue the process with this "tagged" request
    self = [super initWithRequest:theRequest 
                   cachedResponse:cachedResponse 
                           client:client];
    if (self) {
       // capture the data received 
       [self setRequest:newRequest];
       receivedData = [[NSMutableData data] retain];
    }

    [newRequest release];
    return self;
}

- (void)dealloc
{
    [connection release];
    [request release];
    [receivedData release];
    [super dealloc];
}


- (void)startLoading
{
    // Load the data off the web as usual, but set myself up as the delegate 
    // so I can intercept the response data as it comes in.
    [self setConnection:[NSURLConnection connectionWithRequest:request delegate:self]];
}


- (void)stopLoading 
{
    [connection cancel];
}

#pragma mark NSURLConnection delegate implementation

- (void)connection:(NSURLConnection*)conn 
                   didReceiveResponse:(NSURLResponse*)response 
{
    [[self client] URLProtocol:self 
            didReceiveResponse:response 
            cacheStoragePolicy:[request cachePolicy]];
    [receivedData setLength:0];
}


- (void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
{
    [[self client] URLProtocol:self didLoadData:data];
    [receivedData appendData:data];
}


- (void)connectionDidFinishLoading:(NSURLConnection*)conn
{
    [[self client] URLProtocolDidFinishLoading:self];
    [self setConnection:nil];
    if (requestTag != 0) {
        if (requestDelegate && 
            [requestDelegate respondsToSelector:
               @selector(finishedLoadingData:forURL:taggedWith:)]) {
            [requestDelegate finishedLoadingData:receivedData 
                                          forURL:[request URL] 
                                      taggedWith:requestTag];
        }
    }
}


- (void)connection:(NSURLConnection*)conn didFailWithError:(NSError*)error 
{
    [[self client] URLProtocol:self didFailWithError:error];
    [self setConnection:nil];
}