SafeWebView Documentation

SafeWebView allows you to pass a JavaScript function to Java, which can then be executed later (e.g., after an asynchronous operation).

Usage Pattern:

1. Java side: Define a method that accepts a JsCallback object.
2. JS side: Pass a function as an argument to the Java method.

Constraints:

• Parameter Types: Callback arguments in JS must be types that can be converted to a String.
• Lifecycle: By default, a passed JsCallback is single-use. Once jsCallback.apply(...) is called, it cannot be used again. To allow the function to be reused multiple times within the page lifecycle, you must call jsCallback.setPermanent(true) in the Java method.

// Java: Define a method that uses the callback after a delay
@android.webkit.JavascriptInterface
public void delayJsCallBack(final int ms, final String backMsg, final JsCallback jsCallback) {
    new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
        @Override
        public void run() {
            try {
                jsCallback.apply(backMsg);
            } catch (JsCallback.JsCallbackException je) {
                je.printStackTrace();
            }
        }
    }, ms);
}

// Java: Making a callback reusable
@android.webkit.JavascriptInterface
public void test (JsCallback jsCallback) {
    jsCallback.setPermanent(true);
    // ...
}

// JavaScript: Calling the Java method and providing a callback
Android.delayJsCallBack(3 * 1000, 'call back haha', function (msg) {
  HostApp.alert(msg);
});

When customizing the WebChromeClient, extend SafeWebChromeClient. To ensure the bridge functions correctly, you must follow specific rules regarding when to call super in overridden methods:

1. In onProgressChanged: Call super.onProgressChanged(...) as the first line of the method body.
2. In onJsPrompt: Call super.onJsPrompt(...) as the last line of the method body (or use conditional logic).

public class InnerChromeClient extends SafeWebChromeClient {

    @Override
    public void onProgressChanged (WebView view, int newProgress) {
        super.onProgressChanged(view, newProgress); // MUST be the first line
        // your work
    }

    @Override
    public boolean onJsPrompt(WebView view, String url, String message, String defaultValue, JsPromptResult result) {
        // your work
        return super.onJsPrompt(view, url, message, defaultValue, result); // MUST be the last line
    }
}