Add custom headers to WebView resource requests - android

Question

I need to add custom headers to EVERY request coming from the WebView   I know loadURL has the parameter for extraHeaders  but those are only applied to the initial request   All subsequent requests do not contain the headers   I have looked at all overrides in WebViewClient  but nothing allows for adding headers to resource requests - onLoadResource WebView view  String url     Any help would be wonderful   Thanks  Ray

User · Answer

Here is an implementation using HttpUrlConnection:

class CustomWebviewClient : WebViewClient() {
    private val charsetPattern = Pattern.compile(".*?charset=(.*?)(;.*)?$")

    override fun shouldInterceptRequest(view: WebView, request: WebResourceRequest): WebResourceResponse? {
        try {
            val connection: HttpURLConnection = URL(request.url.toString()).openConnection() as HttpURLConnection
            connection.requestMethod = request.method
            for ((key, value) in request.requestHeaders) {
                connection.addRequestProperty(key, value)
            }

            connection.addRequestProperty("custom header key", "custom header value")

            var contentType: String? = connection.contentType
            var charset: String? = null
            if (contentType != null) {
                // some content types may include charset => strip; e. g. "application/json; charset=utf-8"
                val contentTypeTokenizer = StringTokenizer(contentType, ";")
                val tokenizedContentType = contentTypeTokenizer.nextToken()

                var capturedCharset: String? = connection.contentEncoding
                if (capturedCharset == null) {
                    val charsetMatcher = charsetPattern.matcher(contentType)
                    if (charsetMatcher.find() && charsetMatcher.groupCount() > 0) {
                        capturedCharset = charsetMatcher.group(1)
                    }
                }
                if (capturedCharset != null && !capturedCharset.isEmpty()) {
                    charset = capturedCharset
                }

                contentType = tokenizedContentType
            }

            val status = connection.responseCode
            var inputStream = if (status == HttpURLConnection.HTTP_OK) {
                connection.inputStream
            } else {
                // error stream can sometimes be null even if status is different from HTTP_OK
                // (e. g. in case of 404)
                connection.errorStream ?: connection.inputStream
            }
            val headers = connection.headerFields
            val contentEncodings = headers.get("Content-Encoding")
            if (contentEncodings != null) {
                for (header in contentEncodings) {
                    if (header.equals("gzip", true)) {
                        inputStream = GZIPInputStream(inputStream)
                        break
                    }
                }
            }
            return WebResourceResponse(contentType, charset, status, connection.responseMessage, convertConnectionResponseToSingleValueMap(connection.headerFields), inputStream)
        } catch (e: Exception) {
            e.printStackTrace()
        }
        return super.shouldInterceptRequest(view, request)
    }

    private fun convertConnectionResponseToSingleValueMap(headerFields: Map<String, List<String>>): Map<String, String> {
        val headers = HashMap<String, String>()
        for ((key, value) in headerFields) {
            when {
                value.size == 1 -> headers[key] = value[0]
                value.isEmpty() -> headers[key] = ""
                else -> {
                    val builder = StringBuilder(value[0])
                    val separator = "; "
                    for (i in 1 until value.size) {
                        builder.append(separator)
                        builder.append(value[i])
                    }
                    headers[key] = builder.toString()
                }
            }
        }
        return headers
    }
}

Note that this does not work for POST requests because WebResourceRequest doesn't provide POST data. There is a Request Data - WebViewClient library which uses a JavaScript injection workaround for intercepting POST data.

User · Answer

You should be able to control all your headers by skipping loadUrl and writing your own loadPage using Java s HttpURLConnection  Then use the webview s loadData to display the response   There is no access to the headers which Google provides  They are in a JNI call  deep in the WebView source

User · Answer

This worked for me  Create WebViewClient like this below and set the webclient to your webview  I had to use webview loadDataWithBaseURL as my urls  in my content  did not have the baseurl but only relative urls  You will get the url correctly only when there is a baseurl set using loadDataWithBaseURL   public WebViewClient getWebViewClientWithCustomHeader        return new WebViewClient              Override         public WebResourceResponse shouldInterceptRequest WebView view  String url                try                   OkHttpClient httpClient   new OkHttpClient                    com squareup okhttp Request request   new com squareup okhttp Request Builder                            url url trim                             addHeader   lt your-custom-header-name gt      lt your-custom-header-value gt                             build                    com squareup okhttp Response response   httpClient newCall request  execute                     return new WebResourceResponse                          response header  content-type   response body   contentType   type        You can set something other as default content-type                         response header  content-encoding    utf-8        Again  you can set another encoding as default                         response body   byteStream                                    catch  ClientProtocolException e                      return null to tell WebView we failed to fetch it WebView should try again                  return null                catch  IOException e                      return null to tell WebView we failed to fetch it WebView should try again                  return null

User · Answer

This works for me    First you need to create method  which will be returns your headers you want to add to request   private Map lt String  String gt  getCustomHeaders         Map lt String  String gt  headers   new HashMap lt  gt         headers put  YOURHEADER    VALUE        return headers     Second you need to create WebViewClient   private WebViewClient getWebViewClient          return new WebViewClient               Override      TargetApi Build VERSION CODES LOLLIPOP      public boolean shouldOverrideUrlLoading WebView view  WebResourceRequest request                view loadUrl request getUrl   toString    getCustomHeaders             return true              Override     public boolean shouldOverrideUrlLoading WebView view  String url                view loadUrl url  getCustomHeaders             return true              Add WebViewClient to your WebView   webView setWebViewClient getWebViewClient        Hope this helps

User · Answer

I came accross the same problem and solved   As said before you need to create your custom WebViewClient and override the shouldInterceptRequest method    WebResourceResponse shouldInterceptRequest WebView view  WebResourceRequest request    That method should issue a webView loadUrl while returning an  empty  WebResourceResponse   Something like this    Override public boolean shouldInterceptRequest WebView view  WebResourceRequest request            Check for  recursive request   are yor header set       if  request getRequestHeaders   containsKey  Your Header            return null          Add here your headers  could be good to import original request header here         Map lt String  String gt  customHeaders   new HashMap lt String  String gt         customHeaders put  Your Header   Your Header Value        view loadUrl url  customHeaders        return new WebResourceResponse         null

User · Answer

You will need to intercept each request using WebViewClient shouldInterceptRequest  With each interception  you will need to take the url  make this request yourself  and return the content stream   WebViewClient wvc   new WebViewClient          Override     public WebResourceResponse shouldInterceptRequest WebView view  String url             try               DefaultHttpClient client   new DefaultHttpClient                HttpGet httpGet   new HttpGet url               httpGet setHeader  MY-CUSTOM-HEADER    header value                httpGet setHeader HttpHeaders USER AGENT   custom user-agent                HttpResponse httpReponse   client execute httpGet                Header contentType   httpReponse getEntity   getContentType                Header encoding   httpReponse getEntity   getContentEncoding                InputStream responseInputStream   httpReponse getEntity   getContent                 String contentTypeValue   null              String encodingValue   null              if  contentType    null                    contentTypeValue   contentType getValue                              if  encoding    null                    encodingValue   encoding getValue                              return new WebResourceResponse contentTypeValue  encodingValue  responseInputStream             catch  ClientProtocolException e                  return null to tell WebView we failed to fetch it WebView should try again              return null            catch  IOException e                   return null to tell WebView we failed to fetch it WebView should try again              return null                     Webview wv   new WebView this   wv setWebViewClient wvc     If your minimum API target is level 21  you can use the new shouldInterceptRequest which gives you additional request information  such as headers  instead of just the URL

User · Answer

Use this   webView getSettings   setUserAgentString  User-Agent

User · Answer

You can use this     Override   public boolean shouldOverrideUrlLoading WebView view  String url                        Here put your code                 Map lt String  String gt  map   new HashMap lt String  String gt                     map put  Content-Type   application json                    view loadUrl url  map                   return false

User · Answer

Try   loadUrl String url  Map lt String  String gt  extraHeaders    For adding headers to resources loading requests  make custom WebViewClient and override   API 24   WebResourceResponse shouldInterceptRequest WebView view  WebResourceRequest request  or WebResourceResponse shouldInterceptRequest WebView view  String url

User · Answer

Maybe my response quite late  but it covers API below and above 21 level   To add headers we should intercept every request and create new one with required headers   So we need to override shouldInterceptRequest method called in both cases  1  for API until level 21   2  for API level 21       webView setWebViewClient new WebViewClient                 Handle API until level 21          SuppressWarnings  deprecation            Override         public WebResourceResponse shouldInterceptRequest WebView view  String url                 return getNewResponse url                         Handle API 21           TargetApi Build VERSION CODES LOLLIPOP           Override         public WebResourceResponse shouldInterceptRequest WebView view  WebResourceRequest request                 String url   request getUrl   toString                 return getNewResponse url                      private WebResourceResponse getNewResponse String url                 try                   OkHttpClient httpClient   new OkHttpClient                     Request request   new Request Builder                            url url trim                             addHeader  Authorization    YOU AUTH KEY      Example header                          addHeader  api-key    YOUR API KEY      Example header                          build                     Response response   httpClient newCall request  execute                     return new WebResourceResponse                          null                          response header  content-encoding    utf-8                            response body   byteStream                                     catch  Exception e                    return null                                    If response type should be processed you could change          return new WebResourceResponse                  null      lt - Change here                 response header  content-encoding    utf-8                    response body   byteStream                to          return new WebResourceResponse                  getMimeType url       lt - Change here                 response header  content-encoding    utf-8                    response body   byteStream                and add method          private String getMimeType String url                String type   null              String extension   MimeTypeMap getFileExtensionFromUrl url                if  extension    null                     switch  extension                        case  js                           return  text javascript                       case  woff                           return  application font-woff                       case  woff2                           return  application font-woff2                       case  ttf                           return  application x-font-ttf                       case  eot                           return  application vnd ms-fontobject                       case  svg                           return  image svg xml                                      type   MimeTypeMap getSingleton   getMimeTypeFromExtension extension                              return type

User · Answer

As mentioned before  you can do this    WebView  host    WebView this findViewById R id webView    String url     lt yoururladdress gt      Map  lt String  String gt  extraHeaders   new HashMap lt String  String gt      extraHeaders put  Authorization   Bearer      host loadUrl url extraHeaders     I tested this and on with a MVC Controller that I extended the Authorize Attribute to inspect the header and the header is there

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