java - 如何从SD卡打开pdf

Question

尝试从设备上的下载文件夹中打开 pdf 文件， 我将文件名保存在 firebase 中，现在我想检查该文件是否已在设备上找到，然后打开它，或者从 firebase 下载。

File file = new File(Environment.getExternalStorageDirectory() + "filename");
System.out.println(Environment.getExternalStorageDirectory());

///but when i print Environment.getExternalStorageDirectory() i get 
///storage/emulated/0

if (file.exists()) {
    System.out.println(file.getAbsoluteFile());
    Intent target = new Intent(Intent.ACTION_VIEW);
    target.setDataAndType(Uri.fromFile(file), "application/pdf");
    target = Intent.createChooser(target, "Open File");
    target.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
    Intent intent = Intent.createChooser(target, "Open File");
    try {
        startActivity(intent);
    } catch (ActivityNotFoundException e) {
        e.printStackTrace();
    }
} else {
    System.out.println("file not found");
}

Answer 1

尝试从下载目录获取文件

File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/" + filename);