读文件 Environment.getExternalStorageDirectory()

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

File file = new File(path);
if (file.exists()){
    try {
        BufferedReader bfr = new BufferedReader(new FileReader(path));
        String line = bfr.readLine();
        while (line != null) {
            line = bfr.readLine();
        }
        bfr.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}