9.19每日总结

<%
    List<User> userList = (List<User>) session.getAttribute("u");
    StringBuilder userIds = new StringBuilder();
    for (User user : userList) {
        userIds.append(user.getId()).append(",");
    }
    // 去除最后一个逗号
    if (userIds.length() > 0) {
        userIds.setLength(userIds.length() - 1);
    }

    StringBuilder usernames = new StringBuilder();
    for (User user : userList) {
        usernames.append(user.getUsername()).append(",");
    }
    // 去除最后一个逗号
    if (usernames.length() > 0) {
        usernames.setLength(usernames.length() - 1);
    }
%>