Question

我搜索过，但我没有找到答案。我正在使用HTML5和JavaScript开发基于webview的Android应用。我可以调用Android方法，例如JavaScript中的makeToast()吗？

Answer 1

您可以通过向WebView添加JavaScript接口并向Web视图中运行的JavaScript代码公开特定方法来实现此目的。换句话说，您需要在您在activity / fragment中创建的方法中调用Android的Toast类。

activity_main.xml中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <WebView android:id="@+id/web_view"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"/>

</RelativeLayout>

MainActivity.java

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        WebView webView = (WebView)findViewById(R.id.web_view);
        webView.loadUrl("file:///android_asset/web.html");

        webView.getSettings().setJavaScriptEnabled(true);
        webView.addJavascriptInterface(new WebViewJavaScriptInterface(this), "app");
    }

    /*
     * JavaScript Interface. Web code can access methods in here 
     * (as long as they have the @JavascriptInterface annotation)
     */
    public class WebViewJavaScriptInterface{

        private Context context;

        /*
         * Need a reference to the context in order to sent a post message
         */
        public WebViewJavaScriptInterface(Context context){
            this.context = context;
        }

        /* 
         * This method can be called from Android. @JavascriptInterface 
         * required after SDK version 17. 
         */
        @JavascriptInterface
        public void makeToast(String message, boolean lengthLong){
            Toast.makeText(context, message, (lengthLong ? Toast.LENGTH_LONG : Toast.LENGTH_SHORT)).show();
        }
    }

}

资产/ web.html

<!DOCTYPE html>
<html>
<head>
    <title>JavaScript View</title>

    <script type="text/javascript">

        function showToast(){
            var message = document.getElementById("message").value;
            var lengthLong = document.getElementById("length").checked;

            /* 
                Call the 'makeToast' method in the Java code. 
                'app' is specified in MainActivity.java when 
                adding the JavaScript interface. 
             */
            app.makeToast(message, lengthLong);
            return false;
        }

        /* 
            Call the 'showToast' method when the form gets 
            submitted (by pressing button or return key on keyboard). 
         */
        window.onload = function(){
            var form = document.getElementById("form");
            form.onsubmit = showToast;
        }
    </script>
</head>

<body>

<form id="form">
    Message: <input id="message" name="message" type="text"/><br />
    Long: <input id="length" name="length" type="checkbox" /><br />

    <input type="submit" value="Make Toast" />
</form>

</body>
</html>

A Toast Message

Answer 2

查看WebView addJavascriptInterface()方法：

http://developer.android.com/reference/android/webkit/WebView.html#addJavascriptInterface%28java.lang.Object,%20java.lang.String%29

Answer 3

只是因为它更方便（布局）：

<?xml version="1.0" encoding="utf-8"?>
<WebView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/webView"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />

Answer 4

创建主要活动代码后，您需要创建Javascript代码并从中调用WebviewInterface，让我们看一下示例：

compareAndSwapObject

activity_main.xml

<PackageReference Include="Newtonsoft.Json" Version="11.0.0.0" />

Look at this link to see full example https://www.legendblogs.com/blog/how-to-call-native-java-methods-from-webview-javascript/121764

从JavaScript调用Android方法

4 个答案:

activity_main.xml中

MainActivity.java

资产/ web.html