android - 为手机上的标准下载目录创建文件提供程序，以通过 Intent 发送 PDF 文件

Question

当我将它传递给 PDF 查看器时 - 它出错并声明它无法打开该文件。GoogleViewer 在日志中打印以下内容

2019-01-24 15:36:55.390 23756-23833/? V/LoadDocumentTask: Finish task: LoadDocumentTask(Display Data [PDF : mypdf.pdf] +ContentOpenable, uri: content://com.example.gregm.pdfplaygorund.provider/Download/Download/mypdf.pdf) result=FILE_ERROR time=16ms

发送 Intent 的代码

    String filepath = "storage/emulated/0/Download/mypdf.pdf";
            File file = new File(filepath);
            if(file.exists())
            {
                Log.e("ERRR", "file exists");
            }

            Intent intent = new Intent(Intent.ACTION_VIEW);
            Uri uri = FileProvider.getUriForFile(MainActivity.this, BuildConfig.APPLICATION_ID + ".provider",file);

         intent.setDataAndType(uri, "application/pdf");
            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION |Intent.FLAG_ACTIVITY_NEW_TASK);

            List<ResolveInfo> resInfoList = MainActivity.this.getPackageManager().queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);
            for (ResolveInfo resolveInfo : resInfoList) {
                String packageName = resolveInfo.activityInfo.packageName;
                MainActivity.this.grantUriPermission(packageName, uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION | Intent.FLAG_GRANT_READ_URI_PERMISSION);
            }

            startActivity(intent); // Crashes on this line

res/xml/provider_paths.xml

    <?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-path name="Download" path="."/>
</paths>

安卓 list .xml

 <provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="com.example.gregm.pdfplaygorund.provider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/provider_paths"/>
    </provider>

Answer 1

在 list 中包含这些逻辑是不够的

我还必须请求许可

ActivityCompat.requestPermissions(ma,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                                            MY_PERMISSIONS_WRITE_EXTERNAL_STORAGE);
    ActivityCompat.requestPermissions(ma,
                                    new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
                                    MY_PERMISSIONS_READ_EXTERNAL_STORAGE);

然后上面的代码就可以工作了