从Android的Downloads文件夹获取pdf或doc文件

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

String downloadsPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath();

File downloadsFolder = new File(downloadsPath);
File[] files = downloadsFolder.listFiles(new FilenameFilter() {
    @Override
    public boolean accept(File dir, String name) {
        return name.toLowerCase().endsWith(".pdf") || name.toLowerCase().endsWith(".doc");
    }
});