Android 建立文件目录

    <!--往sdcard中写入数据的权限 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
     <!--在sdcard中建立/删除文件的权限 -->
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission>

    //判断SD卡是否存在
    if(android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED)) {
        String path = Environment.getExternalStorageDirectory() + File.separator + "JanuBookingOnline" + File.separator;
        File file = new File(path);
        if(!file.exists()) {
            file.mkdir();
        }
    }