Question

这是一个检查用户名是否已存在的函数，如果不存在则添加它。它在DepartmentBean类中。

私人列表用户;

<div class="container">
    <div class="row">
        <div class="menu-page" data-page="1">
            <div class="col-lg-6" style="background-color: red; height: 200px;">
            </div>
            <div class="col-lg-6" style="background-color: yellow; height: 200px;">
            </div>
        </div>
        <div class="menu-page" data-page="2">
            <div class="col-lg-6" style="background-color: red; height: 200px;">
            </div>
            <div class="col-lg-6" style="background-color: yellow; height: 200px;">
            </div>
        </div>
    </div>
</div>

在Servlet中，我检查这样的标志：

public List<UserBean> getUsers() {
    return users;
}

public int flag;

public int getFlag() {
    return flag;
}


public void setFlag(int flag) {
    this.flag = flag;
}

public void addIfAbsent(UserBean userBean) {

            if (users.stream().anyMatch(x -> x.getUsername().equals(userBean.getUsername()))) {
        setFlag(1);// flag to indicate that there is user with the same name

            } else {

                setFlag(2);
           users.add(userBean);// add the user

            }
        }

如果这是因为大括号正在工作并且记录是maken。但是，如果我使用它，它不会，并带我到白页而不是index.jsp。

这是Servlet中的写入和读取函数：

    DepartmentBean dp = new DepartmentBean();
    UserBean user = new UserBean();//UserBean is class which store name and password
    DepartmentBean departmentBean = read();
    String userName = request.getParameter("username");
    String password = request.getParameter("password");


    user.setPassowrd(password);
    user.setUsername(userName);
    departmentBean.addIfAbsent(user);

         if(dp.flag == 2)//if flag is 2, their's no user with the same name, so write it
         {

    RequestDispatcher rd=request.getRequestDispatcher("index.jsp");
    rd.forward(request, response);
    write(departmentBean);//write to xml

         }

Answer 1

我看到你正在使用两个DepartmentBean变量：一个名为“dp”，一个名为“departmentBean”。您使用后者检查是否已存在用户（因此“departmentBean.flag”被修改）和“dp”以检查标志的值（在代码之前尚未修改）。我建议这样做：

DepartmentBean departmentBean = new DepartmentBean();
UserBean user = new UserBean();
String userName = request.getParameter("username");
String password = request.getParameter("password");


user.setPassowrd(password);
user.setUsername(userName);
departmentBean.addIfAbsent(user);

if(departmentBean.flag == 2)
{

    RequestDispatcher rd=request.getRequestDispatcher("index.jsp");
    rd.forward(request, response);
    write(departmentBean);//write to xml

}

Java Servlet检查用户名是否已存在

1 个答案: