Question

我正在使用Xamarin.iOS开发iOS应用，并且已经实现了WKNavigationDelegate的DecidePolicy（如果我的网络视图如下）：

        public override void DecidePolicy(WKWebView webView, WKNavigationResponse navigationResponse, Action<WKNavigationResponsePolicy> decisionHandler)
    {
        if (webView.Url.AbsoluteString == @"www.myurl.com")
        {
            var response = navigationResponse.Response as NSHttpUrlResponse;
            System.Diagnostics.Debug.WriteLine(response.ToString());

        }
        decisionHandler?.Invoke(WKNavigationResponsePolicy.Allow);
    }

此页面上有一个按钮，当单击该按钮时，它将称为“ POST”表单。依次提交表单并返回HTTP Status 200以及仅响应表单主体中的隐藏元素。我想检索这些隐藏的元素，以便在我的应用中进行进一步处理。

我的问题有两个部分：

上面的响应对象仅包含标头响应，我需要获取响应的正文

我实际上不知道从上方使用覆盖的DecidePolicy（..）时是否已在该URL上提交表单？我可以使用其他DecidePolicy来实现：

public override void DecidePolicy(WKWebView webView, WKNavigationAction navigationAction, Action<WKNavigationActionPolicy>decisionHandler) 
{
    if (navigationAction.NavigationType == WKNavigationType.FormSubmitted)
    {
        //perform logic
    } 
}

但是我不知道如何从这种方法的变体中检索响应主体。非常感谢您的帮助。

Answer 1

我也刚要实现这个，我想我会发布它也许可以帮助其他人。

我的用例是我需要向某些请求注入一个 Authorization 标头，我设法使用相当标准的 WKNavigationDelegate 实现来实现。为此，我将取消现有请求，创建一个副本并注入我更改的标头，然后在保留 cookie 和现有连接属性的同一浏览器中重新提交请求。然而，有些调用失败了，我后来发现 POST 没有返回任何正文数据。

这就是我今天的工作方式；

public override async void DecidePolicy(WKWebView webView, WKNavigationAction navigationAction, Action<WKNavigationActionPolicy> decisionHandler)
        {  
            if (ShouldInjectAuthorizationHeader(navigationAction.Request))
            {
                decisionHandler(WKNavigationActionPolicy.Cancel);
                webView.LoadRequest(await CreateRequestWithAuthorisationHeader(webView, navigationAction.Request));                
            }
            else
            {
                decisionHandler(WKNavigationActionPolicy.Allow);
            }
        }

这只是为了封装我正在检查是否需要修改调用的决策策略的逻辑。

ShouldInjectAuthorizationHeader 上面只是检查 request.Url 是否存在于已知 url 列表中，然后我检查现有标头是否已存在授权。

    private async Task<NSUrlRequest> CreateRequestWithAuthorisationHeader(WKWebView webView, NSUrlRequest request)
{
    var newRequest = (NSMutableUrlRequest)request.MutableCopy();
    newRequest.ShouldHandleCookies = request.ShouldHandleCookies;

    var requestModified = false;
    //This is not needed usually but i recheck here that i have an accesstoken to use and that the url requires it
    if (string.IsNullOrEmpty(AccessToken) == false && WebEx.DoesUrlMatchAnyPartial(request.Url.ToString(), InterceptUrls))
    {
        // inject the HTTP header
        var headers = request.Headers == null ? new NSMutableDictionary() : new NSMutableDictionary(request.Headers);
        headers.Add(new NSString("Authorization"), new NSString($"Bearer {AccessToken}"));

        newRequest.Headers = headers;
        if(request.HttpMethod == "POST")
        {
            try
            {
                //WKWebview has a 5 year running bug Apple https://bugs.webkit.org/show_bug.cgi?id=140188 
                //that the POST form data is not returned and not available so we run some custom javascript to serialise and expose it
                //then manually copy it over and set up the correct headers for it
                //Serilise form library from https://code.google.com/archive/p/form-serialize/
                var javascript = @"
function serialize(form){if(!form||form.nodeName!==""FORM""){return }var i,j,q=[];for(i=form.elements.length-1;i>=0;i=i-1){if(form.elements[i].name===""""){continue}switch(form.elements[i].nodeName){case""INPUT"":switch(form.elements[i].type){case""text"":case""hidden"":case""password"":case""button"":case""reset"":case""submit"":q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value));break;case""checkbox"":case""radio"":if(form.elements[i].checked){q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value))}break;case""file"":break}break;case""TEXTAREA"":q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value));break;case""SELECT"":switch(form.elements[i].type){case""select-one"":q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value));break;case""select-multiple"":for(j=form.elements[i].options.length-1;j>=0;j=j-1){if(form.elements[i].options[j].selected){q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].options[j].value))}}break}break;case""BUTTON"":switch(form.elements[i].type){case""reset"":case""submit"":case""button"":q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value));break}break}}return q.join(""&"")};

serialize(document.querySelector('form'));";
                var result = await webView.EvaluateJavaScriptAsync(javascript);

                var data = result?.ToString();
                if (string.IsNullOrWhiteSpace(data) == false)
                {
                    newRequest.Body = data;
                    newRequest["Content-Length"] = $"{newRequest.Body.Length}";
                    newRequest["Content-Type"] = "application/x-www-form-urlencoded";
                }
            }
            catch(NSErrorException ex)
            {
                Log.Error(ex, $"WKWebViewNavigationDelegate.CreateRequestWithAuthorisationHeader: JavaScript evaluation exception when trying to get Form post data, {ex.Message}");
            }
        }
        requestModified = true;
    }
    if (requestModified)
    {
        return newRequest;
    }
    return request;
}

我为这篇文章稍微简化了上述两种方法，删除调试输出并清理变量，但大多数情况下它在我们的系统中运行

<块引用>

看起来堆栈溢出不喜欢双引号缩小的js if 您想下载它并从 minified js for extracting form data 重新插入它，我将它放入文本编辑器并用“”替换所有“以允许它在@””字符串中内联解析

如果你不需要授权承载的东西，它会减少很多代码

基本上，我将 WKWebView 传递给该方法并在其中运行 javascript 以在其 POST 时提取表单数据，然后将其复制到新请求，用

取消旧请求

decisionHandler(WKNavigationActionPolicy.Cancel);

并使用 LoadRequest 将 webview 重定向到原始的新 MutableCopy，并带有额外的标头和手动插入的 POST 数据

webView.LoadRequest(await CreateRequestWithAuthorisationHeader(webView, navigationAction.Request));

这似乎现在工作正常

对于您的要求 John，您应该能够非常轻松地使用现有代码获取数据

public override void DecidePolicy(WKWebView webView, WKNavigationAction navigationAction, Action<WKNavigationActionPolicy>decisionHandler) 
{
    if (navigationAction.NavigationType == WKNavigationType.FormSubmitted)
    {
        //perform logic
var javascript = @"
function serialize(form){if(!form||form.nodeName!==""FORM""){return }var i,j,q=[];for(i=form.elements.length-1;i>=0;i=i-1){if(form.elements[i].name===""""){continue}switch(form.elements[i].nodeName){case""INPUT"":switch(form.elements[i].type){case""text"":case""hidden"":case""password"":case""button"":case""reset"":case""submit"":q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value));break;case""checkbox"":case""radio"":if(form.elements[i].checked){q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value))}break;case""file"":break}break;case""TEXTAREA"":q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value));break;case""SELECT"":switch(form.elements[i].type){case""select-one"":q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value));break;case""select-multiple"":for(j=form.elements[i].options.length-1;j>=0;j=j-1){if(form.elements[i].options[j].selected){q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].options[j].value))}}break}break;case""BUTTON"":switch(form.elements[i].type){case""reset"":case""submit"":case""button"":q.push(form.elements[i].name+""=""+encodeURIComponent(form.elements[i].value));break}break}}return q.join(""&"")};

serialize(document.querySelector('form'));";
                var result = await webView.EvaluateJavaScriptAsync(javascript);

                var data = result?.ToString();
                if (string.IsNullOrWhiteSpace(data) == false)
                {
/*
url encoded form data in data
You could replace the & with something else if you want it in a different format or try different javascript method, I found a few but I was after Url encoded so didn't experiment further, there were some alternatives that allowed for json format instead of url format
*/
}
    } 
}

在WKWebView DecidePolicy中获取表单发布响应正文

1 个答案: