objective-c - 在 WebKit 中，如何获取资源的内容？

Question

我一直在编写一个 Mac 应用程序来检查每个 HTTP 请求，因此我使用 WebView 来加载请求。

问题是我似乎无法弄清楚如何获取每个资源项的内容。

我正在尝试通过 WebResourceLoadDelegate 方法获取资源的内容:

- (void)webView:(WebView *)sender resource:(id)identifier didFinishLoadingFromDataSource:(WebDataSource *)dataSource

这似乎不起作用。

我也在查看 [dataSource data]，但那只是为我提供了请求的 HTML 而不是资源项的数据。

关于如何获取资源内容的任何想法？

Answer 1

是的，这应该行得通，而且似乎曾几何时它行得通。您可以通过实现自定义 NSURLProtocol 来解决它。

首先，您需要确定您有兴趣拦截哪些请求(或所有请求，无论如何)。我在我的 WebResourceLoadDelegate 中执行此操作。如果我关心这个请求，我会用我自己的请求替换它，将自己作为属性(property)附加。稍后我将在 NSURLProtocol 中使用该属性。

- (NSURLRequest*) webView:(WebView*)sender 
                 resource:(id)identifier 
          willSendRequest:(NSURLRequest*)request 
         redirectResponse:(NSURLResponse*)redirectResponse     
           fromDataSource:(WebDataSource*)dataSource
{
    // Am I interested in this request?
    if (/* figure out if you want it or not */) {
        NSMutableURLRequest* newRequest = [[request mutableCopy] autorelease];
        [NSURLProtocol setProperty:self forKey:@"MyApp" inRequest:newRequest];
        return newRequest;
    }
    else {  
        // Not interested, let it go through normally
        return request;
    }
}

我的 NSURLProtocol 看起来像这样。

@interface MyURLProtocol : NSURLProtocol {
    id _delegate;
    NSURLConnection* _connection;
    NSMutableData* _data;
}
@end

在我的 NSURLProtocol 子类中，我可以使用附加属性来查看我是否应该拦截响应。

+ (BOOL) canInitWithRequest:(NSURLRequest*)request
{   
    id delegate = [NSURLProtocol propertyForKey:@"MyApp" inRequest:request];
    return (delegate != nil);
}

在 initWithRequest 中，我将委托(delegate)移动到我的 NSURLProtocol 实例中，并从请求中删除该属性。这可以防止以后我实际尝试加载此请求时出现无限循环。

- (id) initWithRequest:(NSURLRequest*)theRequest 
        cachedResponse:(NSCachedURLResponse*)cachedResponse 
                client:(id<NSURLProtocolClient>)client
{
    // Move the delegate from the request to this instance
    NSMutableURLRequest* req = (NSMutableURLRequest*)theRequest;    
    _delegate = [NSURLProtocol propertyForKey:@"MyApp" inRequest:req];  
    [NSURLProtocol removePropertyForKey:@"MyApp" inRequest:req];

    // Complete my setup
    self = [super initWithRequest:req cachedResponse:cachedResponse client:client];
    if (self) {
        _data = [[NSMutableData data] retain];
    }
    return self;
}

剩下的就是库存 URL 加载内容。

- (void) startLoading
{
    _connection = [[NSURLConnection connectionWithRequest:[self request] delegate:self] retain];
}

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

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

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

- (void)connectionDidFinishLoading:(NSURLConnection*)conn
{
    [[self client] URLProtocolDidFinishLoading:self];

    // Forward the response to your delegate however you like
    if (_delegate && [_delegate respondsToSelector:@selector(...)]) {
        [_delegate ... withRequest:[self request] withData:_data];
    }
}

- (NSURLRequest*)connection:(NSURLConnection*)connection willSendRequest:(NSURLRequest*)theRequest redirectResponse:(NSURLResponse*)redirectResponse
{
    return theRequest;
}

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