问内存读写

EN

 downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
Uri uri = Uri.parse("http://");
DownloadManager.Request request = new DownloadManager.Request(uri);
request.setDestinationInExternalFilesDir(this, "/download", "app-debug.apk");
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
Long reference = downloadManager.enqueue(request);

File imagePath = new File(getFilesDir(), "download");
File newFile = new File(imagePath, "app-debug.apk");
CharSequence text1 = "no file";
Toast toast1 = Toast.makeText(getApplicationContext(), newFile.getAbsolutePath()+"can't find file ", Toast.LENGTH_SHORT);

if(!newFile.exists()){toast1.show(); return false;}
Uri uri2 = FileProvider.getUriForFile(this,"com.example.xxx",newFile);
Intent i = new Intent();
i.setAction(android.content.Intent.ACTION_VIEW);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
i.setData(uri2);
i.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
i.setType("application/vnd.android.package-archive");
startActivity(i);

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<!--<external-path name="external_files" path="."/>-->
<files-path
 name="tlumacz1"
path="download"/>
</paths>

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