在WebView Android中扫描条形码

Question

我试图启动条形码扫描器上的用户按下一个按钮在HTML。然而，我又犯了一个错误：

Uncaught TypeError: Object [object Object] has no method 'scanBarcode'", source: file:///android_asset/www/index.html (49)

在javascript中使用：

function scanner(){ 
        Android.scanBarcode();
    }

现在，在Java文件中，我有以下代码，它在公共类JavaScriptInterface中声明函数

public class MainActivity extends Activity {
@SuppressWarnings("deprecation")
@SuppressLint("SetJavaScriptEnabled") @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.activity_main);
    WebView myWebView = (WebView)findViewById(R.id.webView);
    myWebView.addJavascriptInterface(new WebAppInterface(this), "Android");
    myWebView.setInitialScale(1);
    WebSettings webSettings = myWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);

    webSettings.setBuiltInZoomControls(false);
    webSettings.setSupportZoom(true);
    webSettings.setJavaScriptEnabled(true);
    webSettings.setLoadWithOverviewMode(true);
    webSettings.setUseWideViewPort(true);
    //webView.getSettings().setJavaScriptEnabled(true);
    myWebView.setWebChromeClient(new WebChromeClient());
    //myWebView.setWebViewClient(new WebViewClient());
    myWebView.loadUrl("file:///android_asset/www/index.html");
}

public class JavaScriptInterface {
    Context mContext;

    // Instantiate the interface and set the context
    JavaScriptInterface(Context c) {
        mContext = c;
    }

    // using Javascript to call the finish activity
    public void closeMyActivity() {
        finish();
    }

    public void scanBarcode() {
        Intent intent = new Intent("com.google.zxing.client.android.SCAN");
        intent.setPackage("com.google.zxing.client.android");
        startActivityForResult(intent, 0);
    }
}   //JavascriptInterface

public void onActivityResult(int requestCode, int resultCode, Intent intent) {
    if (requestCode == 0) {
        if (resultCode == RESULT_OK) {
            //here is where you get your result
            String barcode = intent.getStringExtra("SCAN_RESULT");
        }
    }
}

Answer 1

...
    myWebView.addJavascriptInterface(new WebAppInterface(this), "Android");
...
public class JavaScriptInterface {

您已经调用了接口类JavaScriptInterface，但创建了一个新的WebAppInterface来传递给WebView。

上面的答案仍然成立：您从未在WebView中注册接口(JavaScriptInterface)，因此您将无法访问这些方法（扫描条形码）。

由于WebView中实际上需要两个接口，因此需要添加两个接口

myWebView.addJavascriptInterface(new WebAppInterface(this), "Android");
myWebView.addJavascriptInterface(new JavaScriptInterface(this), "Scanner");

function scanner() {
    Scanner.scanBarcode();
}

public class JavaScriptInterface {
...
    @JavascriptInterface
    public void scanBarcode() {
    ...
    }
}