Question

我是否试图从我的Web View Android应用程序下载文件？我是android开发的新手。而且我不知道我的代码有什么问题。

*

错误：（31,57）错误：找不到符号方法   getSystemService（String）错误：任务执行失败   ＆＃39;：应用程序：compileDebugJavaWithJavac＆＃39;


编译失败;有关详细信息，请参阅编译器错误输出。

*

这是我的代码： MyAppWebViewClient.java

public class MyAppWebViewClient extends WebViewClient {

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {

        if (url.contains(".apk")) {
            Uri source = Uri.parse(url);
            // Make a new request pointing to the .apk url
            DownloadManager.Request request = new DownloadManager.Request(source);
            // appears the same in Notification bar while downloading
            request.setDescription("Description for the DownloadManager Bar");
            request.setTitle("YourApp.apk");
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                request.allowScanningByMediaScanner();
                request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            }
            // save the file in the "Downloads" folder of SDCARD
            request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "SmartPigs.apk");
            // get download service and enqueue file
            DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
            manager.enqueue(request);
            return true;
        }

        if (Uri.parse(url).getHost().contains("mysite.com")) {
            return false;
        }

        Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
        view.getContext().startActivity(intent);
        return true;
    }

}

Answer 1

如果没有非活动类中的上下文，

getSystemService方法将无法工作。试试

的getContext（）。getSystemService（）

Answer 2

对于非活动类（如您的情况MyAppWebViewClient），如果我们想要访问Context类的方法，我们必须使用Context类实例。因此，最好的方法是创建一个构造函数并在参数中传递Context类实例。

public class MyAppWebViewClient extends WebViewClient {
private final Context context;

public MyAppWebViewClient(Context context){
this.context = context;
}
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {

        if (url.contains(".apk")) {
            Uri source = Uri.parse(url);
            // Make a new request pointing to the .apk url
            DownloadManager.Request request = new DownloadManager.Request(source);
            // appears the same in Notification bar while downloading
            request.setDescription("Description for the DownloadManager Bar");
            request.setTitle("YourApp.apk");
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                request.allowScanningByMediaScanner();
                request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            }
            // save the file in the "Downloads" folder of SDCARD
            request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "SmartPigs.apk");
            // get download service and enqueue file
            DownloadManager manager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
            manager.enqueue(request);
            return true;
        }

        if (Uri.parse(url).getHost().contains("mysite.com")) {
            return false;
        }

        Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
        view.getContext().startActivity(intent);
        return true;
    }

}

每当从活动类调用MyAppWebViewClient类时，只需在创建同一类的新实例时传递活动上下文。像

MyAppWebViewClient myAppWebViewClient = new MyAppWebViewClient(YourActivityName.this);

希望这会对你有所帮助。

从Web View Android应用程序下载文件

2 个答案: