How to get the body of the WebResourceRequest in android webView?

In Android development, WebView is a powerful component that enables developers to embed web pages directly within an application. However, obtaining the request body of WebResourceRequest can be a complex issue because the native WebView of Android does not natively support capturing the body of HTTP requests, such as POST data.

Solutions:

1. Using JavaScriptInterface

Steps:

1. Inject a JavaScriptInterface into WebView.
2. Inject JavaScript code into the webpage to intercept form submissions and retrieve form data.
3. Send the data back to the Android application via JavaScriptInterface.

Example Code:

java
class WebAppInterface {
    Context mContext;

    WebAppInterface(Context c) {
        mContext = c;
    }

    @JavascriptInterface
    public void postData(String data) {
        // Process data received from the webpage
        Log.d("WebView", "Received post data: " + data);
    }
}

webView.getSettings().setJavaScriptEnabled(true);
webView.addJavascriptInterface(new WebAppInterface(this), "Android");

// Inject JavaScript after page load
webView.setWebViewClient(new WebViewClient() {
    @Override
    public void onPageFinished(WebView view, String url) {
        super.onPageFinished(view, url);
        injectJavaScript(view);
    }

    private void injectJavaScript(WebView view) {
        view.loadUrl("javascript:document.forms[0].onsubmit = function () {" +
                     "   var obj = {}; for (var i = 0; i < this.elements.length; i++) {" +
                     "       obj[this.elements[i].name] = this.elements[i].value;" +
                     "   }" +
                     "   Android.postData(JSON.stringify(obj));" +
                     "};");
    }
});

2. Using Custom WebViewClient and shouldInterceptRequest

In Android 5.0 and above, you can intercept requests by overriding the shouldInterceptRequest method of WebViewClient. However, this approach still cannot directly access POST data because WebResourceRequest does not expose the request body.

3. Using Proxy

Set up an HTTP proxy through which all WebView requests pass. In the proxy, you can capture the complete HTTP request, including headers and body. While this method is relatively complex—requiring handling of request forwarding, encryption, and other network issues—it provides full control over WebView traffic.

Summary

Each method has specific use cases and limitations. For capturing simple form submission data, using JavaScriptInterface is typically the simplest approach. For deeper analysis or modification of WebView network requests, consider implementing a proxy server.