在表中显示从数据库中检索的值

Question

我对 hibernate 框架很陌生，我正在 netbeans IDE 中开发一个 Hibernate 框架项目。我有一个连接到项目的 javadb，我需要获取每个员工的任务列表，并将其显示为 <td> 中针对每个员工姓名的项目符号列表。下表显示了使用 EmployeeHelper 类中的 getEmployeeDetails 方法获取的员工姓名和角色。

问题
- 尽管我调用了从控制器传递的 resultTaskList 参数，但任务列表始终为空。
- 我知道我必须对嵌套 forloop 中的任务进行 if 条件检查这将列出根据员工姓名对它们进行分组的任务。但我不确定如何在 jsp 页面中使用if。

任何关于如何在同一个表中显示每个员工的任务列表的建议都将受到高度赞赏。

在此表中，我打算将与每个员工有关的任务作为每个对应的<td> 中的项目符号列表。

Employee.jsp

...
<div class="content">
<!--Display table of roles with an edit button against each role-->
<form method="get" action="<%= request.getContextPath() %>/RoleController">
    <br>

    <table border ="2">
        <thead class="thead-inverse">
            <tr>
              <th></th>
              <th>Employee Name</th>
              <th>Role</th>
              <th>Tasks</th>
              <th>Edit</th>
            </tr>
          </thead>
          <tbody>
            <c:forEach items="${result}" var="res">
                <tr>
                    <th scope="row">
                    </th>
                    <td>
                        <c:out value="${res[0]}"></c:out>
                    </td>
                    <td>
                        <c:out value="${res[1]}"></c:out>
                    </td>
                    <td>
                        <c:out value="${resultTaskList[1]}"></c:out>
                    </td>
                    <td>
                        <input type="button" class="btn btn-info" value="Edit Role">
                    </td>
                </tr>
            </c:forEach>
    </table>
</form>
</div>
...

EmployeeController.java

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    EmployeeHelper helper = new EmployeeHelper();
    List<Employee> resultTaskList = helper.getEmployeeTasks();
    request.setAttribute("resultTaskList", resultTaskList);
    List<Employee> result = helper.getEmployeeDetails();
    request.setAttribute("result", result);
    request.getRequestDispatcher("Employee.jsp").forward(request, response);
}

EmployeeHelper.java

public class EmployeeHelper {
    Session session = null;

    public EmployeeHelper(){
        this.session = HibernateUtil.getSessionFactory().openSession();
    }


    public List getEmployeeDetails(){
        Transaction tx = this.session.beginTransaction();

        List<Employee> employeeList = null;

        try{
            Query query = session.createQuery("select e.name, r.title from Employee as e, Role as r where e.employeeid=r.employeeid");
            employeeList = (List<Employee>)query.list();
            tx.commit();
        }
        catch(HibernateException ex){
            ex.printStackTrace();
            tx.rollback();
        }
        return employeeList;
    }

    public List getEmployeeTasks(){
        Transaction tx = this.session.beginTransaction();

        List<Employee> employeeTaskList = null;

        try{
            Query query = session.createQuery("select e.name, t.description from Employee as e, Role as r, Task as t, EmployeeTask as et where e.employeeid=r.employeeid and t.taskid=et.taskid and e.employeeid=et.employeeid");
            employeeTaskList = (List<Employee>)query.list();
            tx.commit();
        }
        catch(HibernateException ex){
            ex.printStackTrace();
            tx.rollback();
        }
        return employeeTaskList;
    }
}

在 getEmployeeTasks() 方法中执行的 SQL 查询

Answer 1

代替 List employeeTaskList 使用 List 和迭代循环并在员工列表中设置值尝试以下代码。

   public List getEmployeeTasks(){

    Transaction tx = this.session.beginTransaction();

    List<Employee> employeeTaskList = null;

    try{
       session.beginTransaction();
      Query query = session.createQuery("select e.name, t.description from Employee as e, Role as r, Task as t, EmployeeTask as et where e.employeeid=r.employeeid and t.taskid=et.taskid and e.employeeid=et.employeeid");
        List<Object[]> result = (List<Object[]>) query.list();

    if (null != result && result.size() != 0) {

            for (Object[] obj : result) {
                //Set values over here 
                employeeTaskList.set.....
            }
        tx.commit();
    }
    }
    catch(HibernateException ex){
        ex.printStackTrace();
        tx.rollback();
    }
    return employeeTaskList;
}

Answer 2

这两个列表不相关，正如 JB Nizet 所建议的那样。你仍然可以这样做。

        <c:forEach items="${result}" var="res">
            <tr>
                <th scope="row">
                </th>
                <td>
                    <c:out value="${res[0]}"></c:out>
                </td>
                <td>
                    <c:out value="${res[1]}"></c:out>
                </td>
                <td>
                <c:forEach items="${resultTaskList}" var="resultTaskList">
                    <c:if test = "${res[0] == resultTaskList[0]}">
                    <c:out value="${resultTaskList[1]}"></c:out>
                    </c:if>
                </c:forEach>
                </td>
                <td>
                    <input type="button" class="btn btn-info" value="Edit Role">
                </td>
            </tr>
        </c:forEach>

希望这会有所帮助。