java - 无法从 webview android 中从 Javascript 调用的 Java 方法获取数据

Question

我正在开发一个应用程序，当我单击 web View 中的链接并期望该方法的结果时，我会在其中执行 Java 方法。在那个方法中，我用 startActivityForResult 开始了另一个 Activity ，它工作得很好(我在那个 Activity 上放了一些日志，一切都很好)，但看起来这个方法没有返回任何东西..

这是我的代码:

HTML : (所有包含都可以)

<script type="text/javascript">
    $("#run-qrscan").on("click", function(){

        var qr_data = window.WebAppInterface.startScan(); 
        // startScan is the Java method I call
        // call the function opens the activity etc.. but doesn't get any result 

        $("#display-qrresult").html(qr_data); // doesn't display anything
    });
</script>

我的 Activity :WebActivity.java

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_web);

    WebView webview = (WebView) findViewById(R.id.aw_webView);

    WebAppInterface jsInterface = new WebAppInterface(this);
    webview.getSettings().setJavaScriptEnabled(true);

    webview.setWebChromeClient(new WebChromeClient());

    webview.addJavascriptInterface(jsInterface, "WebAppInterface");
    webview.loadUrl("file:///android_asset/index.html");
}

我的 Javascript 界面:WebAppInterface.java

import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.webkit.JavascriptInterface;

public class WebAppInterface {

    private static Activity activity;
    public static int WEB_APP = 0;

    private static int REQUEST_FOR_ACTIVITY_CODE_SCAN = 1000;
    private static String qr_data = "";
    private static Intent intent;

    public WebAppInterface(Activity activity) {
        WebAppInterface.activity = activity;
    }

    @JavascriptInterface
    public static String startScan() {
        Intent intent = new Intent(activity, ScanActivity.class);
        WEB_APP = 1;

        activity.startActivityForResult(intent, REQUEST_FOR_ACTIVITY_CODE_SCAN);

        //Wait for startActivityForResult to end -since it's asynchronous
        while(WEB_APP == 1) {}

        Log.d("qr_return", qr_data); // Doesn't display it.

        return qr_data; // Empty
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // Scan QR
        if (requestCode == REQUEST_FOR_ACTIVITY_CODE_SCAN) {
            if (resultCode == Activity.RESULT_OK) {
                qr_data = data.getStringExtra("qr_data");
            }
        }
        WEB_APP = 0;
    }
}

那我做错了什么？谢谢。

Answer 1

抱歉，我的错，我没有注意到我调用 startActivityForResult 的类只是一个类而不是 Activity.. 所以当返回数据时它不是回到它..

我发布这段代码以防像我这样的人没有注意到这一点。

1- 删除 WebAppInterface.java 类

2- WebActivity.java :

import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.webkit.JavascriptInterface;
import android.webkit.WebChromeClient;
import android.webkit.WebView;

public class WebActivity extends Activity {

    public static int WEB_APP = 0;

    private static int REQUEST_FOR_ACTIVITY_CODE_SCAN = 1000;
    private static String qr_data = "";

    @SuppressLint("SetJavaScriptEnabled")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_web);

        WebView webview = (WebView) findViewById(R.id.aw_webView);

        WebAppInterface jsInterface = new WebAppInterface();
        webview.getSettings().setJavaScriptEnabled(true);
        webview.setWebChromeClient(new WebChromeClient());
        webview.addJavascriptInterface(jsInterface, "WebAppInterface");
        webview.loadUrl("file:///android_asset/index.html");
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        return false;
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // Scan QR
        if (requestCode == REQUEST_FOR_ACTIVITY_CODE_SCAN) {
            if (resultCode == Activity.RESULT_OK) {
                qr_data = data.getStringExtra("qr_data");

                Log.d("QR", qr_data);
            }
        }
        WEB_APP = 0;
    }

    public class WebAppInterface {

        WebAppInterface() {}

        @JavascriptInterface
        public  String startScan() {
            Intent intent = new Intent(WebActivity.this, ScanActivity.class);
            WEB_APP = 1;

            startActivityForResult(intent, REQUEST_FOR_ACTIVITY_CODE_SCAN);

            while(WEB_APP == 1) {}

            Log.d("qr_return", qr_data);

            return qr_data;
        }
    }
}