在Android中从SD卡打开文件？

Question

我正在尝试打开名为apps.xml的文件，让其他应用处理该文件。我怎么做？我试过这个，但它什么都没做。没有力量关闭

File root = new File(Environment.getExternalStorageDirectory(), "Download");
File gpxfile = new File(root, "list.xml");

和manifest档案

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Answer 1

您可能必须请求运行时权限才能访问该文件，

public void requestPermissionForExternalStorage() {
    if (ActivityCompat.shouldShowRequestPermissionRationale(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
        Toast.makeText(activity, "External Storage permission needed. Please allow in App Settings for additional functionality.", Toast.LENGTH_LONG).show();
    } else {
        ActivityCompat.requestPermissions(activity, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE);
    }
}