我们如何在Android应用程序中执行javascript函数并获取返回值？

Question

How we can execute a javascript function and get a return value in our android appplication ? 我们如何在我们的android应用程序中执行javascript函数并获得返回值？

We want to execute a javascript on a button press event, we need to pass parameters to the script and get return values, So we are using "WebChromeClient" to implement this, But we got Exception is "SyntaxError: Parse error at undefined:1" 我们想在按钮按下事件上执行javascript，我们需要将参数传递给脚本并获取返回值，所以我们使用“WebChromeClient”来实现它，但我们得到的异常是“SyntaxError：未定义的解析错误：1 “

Following is my code 以下是我的代码

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.webkit.JsResult;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;

public class FirstTab extends Activity 
{


    private WebView webView;

    public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
             setContentView(R.layout.regis);

            try{

                webView = (WebView) findViewById(R.id.webView1);
                webView.getSettings().setJavaScriptEnabled(true);
                webView.setWebChromeClient(new MyWebChromeClient());
                String customHtml = "<html><head><title>iSales</title><script type=\"text/javascript\"> function fieldsOnDelete(){ var x=123; return \"JIJO\"; } </script></head><body>hi</body></html>";
                webView.loadData(customHtml, "text/html","UTF-8");  

                }catch(Exception e)
                {
                     Log.v("JAC LOG",e.toString());
                }

        }
    public void onResume()
    {
        super.onResume();

            final Button button = (Button) findViewById(R.id.button1);
             button.setOnClickListener(new View.OnClickListener() {
             public void onClick(View v) {
                 try{
                    webView.loadUrl("javascript:alert(javascript:fieldsOnDelete())");
                 }
                 catch(Exception e)
                 {
                     Log.v("JAC LOG",e.toString());

                 }
              } 
             });
    }


    final class MyWebChromeClient extends WebChromeClient {
        @Override
        public boolean onJsAlert(WebView view, String url, String message, JsResult result) {

        Log.v("LogTag", message);
          result.confirm();
          return true;
        }
    }


}

Answer 1

you can use mWebView.loadUrl("javascript:checkName"); 你可以使用mWebView.loadUrl("javascript:checkName"); to call the method... 打电话给方法......

Then you can use addJavascriptInterface() to add a Java object to the Javascript environment. 然后，您可以使用addJavascriptInterface()将Java对象添加到Javascript环境中。 Have your Java script call a method on that Java object to supply its "return value". 让Java脚本在该Java对象上调用一个方法来提供其“返回值”。

EDIT1: Or you can use following hack: 编辑1：或者您可以使用以下hack：

Add this Client to your WebView: 将此客户端添加到WebView：

final class MyWebChromeClient extends WebChromeClient {
        @Override
        public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
            Log.d("LogTag", message);
            result.confirm();
            return true;
        }
    }

Now in your java script call do: 现在在你的java脚本调用中执行：

webView.loadUrl("javascript:alert(functionThatReturnsSomething)");

Now in the onJsAlert call " message " will contain the returned value. 现在在onJsAlert调用“ message ”中将包含返回的值。

Edit2: EDIT2：

So it does not work if we call javascript method just after call to load the URL since the page loads take time. 因此，如果我们在调用加载URL之后调用javascript方法，它就不起作用，因为页面加载需要时间。 So I created a test program to test that... 所以我创建了一个测试程序来测试......

Following is my html file (named test.html) store in the assets folder: 以下是我的资产文件夹中的html文件（名为test.html）商店：

<html>
<head>
<script language="javascript">
    function fieldsOnDelete(message) {
        alert("i am called with " + message);
        window.myjava.returnValue(message + " JIJO");
    }
</script>
<title>iSales android</title>


</head>
<body></body>
</html>
</body>
</html>

Following is my java class that would get that i would add to java script as interface and it would receive the return value: 以下是我的java类，我将添加到java脚本作为接口，它将收到返回值：

public class MyJS {

    public void returnValue(String string){
        Log.d(this.getClass().getSimpleName(), string);
    }

}

And following is my activity class: 以下是我的活动课程：

public class CheckWebView extends Activity {

    private WebView webView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_check_web_view);
        webView = (WebView) findViewById(R.id.webview);

        webView.setWebChromeClient(new WebChromeClient() {
            @Override
            public void onConsoleMessage(String message, int lineNumber,
                    String sourceID) {
                super.onConsoleMessage(message, lineNumber, sourceID);
                Log.d(this.getClass().getCanonicalName(), "message " + message
                        + "   :::line number " + lineNumber + "   :::source id "
                        + sourceID);
            }

            @Override
            public boolean onConsoleMessage(ConsoleMessage consoleMessage) {
                // TODO Auto-generated method stub

                onConsoleMessage(consoleMessage.message(),
                        consoleMessage.lineNumber(), consoleMessage.sourceId());

                Log.d(this.getClass().getCanonicalName(), "message::::: "
                        + consoleMessage.message());

                return super.onConsoleMessage(consoleMessage);
            }
        });

        webView.addJavascriptInterface(new MyJS(), "myjava");
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setPluginsEnabled(true);
        webView.getSettings().setAllowFileAccess(true);

        webView.loadUrl("file:///android_asset/test.html");

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_check_web_view, menu);
        return true;
    }

    /* (non-Javadoc)
     * @see android.app.Activity#onOptionsItemSelected(android.view.MenuItem)
     */
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        webView.loadUrl("javascript:fieldsOnDelete('name');");
        return super.onOptionsItemSelected(item);
    }

}

The key here is that there should be some time interval between the call to load html file from assets folder and the call to javascript:method . 这里的关键是在从assets文件夹加载html文件和调用javascript:method之间应该有一段时间间隔。 Here I am calling it from onOptionsItemSelected and it is working fine.. if I move the webView.loadUrl("javascript:fieldsOnDelete('name');"); 在这里，我从onOptionsItemSelected调用它，它工作正常..如果我移动webView.loadUrl("javascript:fieldsOnDelete('name');"); to the end of the onCreate() method the it shows the error that it can not find fieldsOnDelete() method... 到onCreate（）方法结束时，它显示错误，它无法找到fieldsOnDelete()方法...

Hope it Helps... 希望能帮助到你...

EDIT3: EDIT3：

Replace following in your code 在代码中替换以下内容

webView.loadUrl("javascript:alert(javascript:fieldsOnDelete())");

with 同

webView.loadUrl("javascript:alert(fieldsOnDelete())");

and try... 并试试......

Answer 2

In Android KitKat there is a new method evaluateJavascript that has a callback for a return value. 在Android KitKat中有一个新方法evaluateJavascript，它具有返回值的回调。 The callback returns a JSON value, object or array depending on what you return. 回调返回JSON值，对象或数组，具体取决于您返回的内容。

        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            // In KitKat+ you should use the evaluateJavascript method
            mWebView.evaluateJavascript(javascript, new ValueCallback<String>() {
                @TargetApi(Build.VERSION_CODES.HONEYCOMB)
                @Override
                public void onReceiveValue(String s) {
                    JsonReader reader = new JsonReader(new StringReader(s));

                    // Must set lenient to parse single values
                    reader.setLenient(true);

                    try {
                        if(reader.peek() != JsonToken.NULL) {
                            if(reader.peek() == JsonToken.STRING) {
                                String msg = reader.nextString();
                                if(msg != null) {
                                    Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_LONG).show();
                                }
                            }
                        }
                    } catch (IOException e) {
                        Log.e("TAG", "MainActivity: IOException", e);
                    } finally {
                        try {
                            reader.close();
                        } catch (IOException e) {
                            // NOOP
                        }
                    }
                }
            });
        }

You can see a full example here: https://github.com/GoogleChrome/chromium-webview-samples/tree/master/jsinterface-example 您可以在此处查看完整示例： https ： //github.com/GoogleChrome/chromium-webview-samples/tree/master/jsinterface-example

我们如何在Android应用程序中执行javascript函数并获取返回值？

问题描述

2 个解决方案

解决方案1
7 已采纳 2012-11-23 11:03:14

解决方案2
4 2013-12-04 14:14:08

我们如何在Android应用程序中执行javascript函数并获取返回值？

问题描述

2 个解决方案

解决方案1 7 已采纳 2012-11-23 11:03:14

解决方案2 4 2013-12-04 14:14:08

解决方案1
7 已采纳 2012-11-23 11:03:14

解决方案2
4 2013-12-04 14:14:08