Question

我有两个表（实体类），需要从两个表中选择并将结果传输到jsp页面。

我的平衡实体：

 @Entity
    @NamedQuery (name = "findLastFiveTransaction",
    query = "select c, b from Categorietype c, Balance b  where c.user = :user and b.user = :user")
    public class Balance implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private String id;

    private BigDecimal sum;
    @Column(name="Description")
    private String descrip;

我的分类实体：

@Entity
public class Categorietype implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private String id;

    private String name;

    //bi-directional many-to-one association to Balance
    @OneToMany(mappedBy="categorietype")
    private List<Balance> balances;

    //bi-directional many-to-one association to User
    @ManyToOne
    @JoinColumn(name="UserID")
    private User user;

EJB类中的方法：

 public List getUserTransaction(User user) {
    return em.createNamedQuery("findLastFiveTransaction").setParameter("user", user).getResultList();
    }

我在jsp页面上的代码：

<table border="1">

  <tr>
    <th>Sum</th>
    <th>Descrip</th>
    <th>Name</th>
  </tr>
<c:forEach items="${result}" var="r">
  <tr>
    <td> ${r.sum} </td>
    <td> ${r.descrip} </td>
    <td> ${r.name} </td>
  </tr>
</c:forEach>
</table>

在这种变体中，我收到消息

org.apache.jasper.JasperException：java.lang.NumberFormatException：对于输入字符串：“sum”

我的问题是如何将解析数据传输到jsp页面。我从我的servlet传输数据：

List result = balance.getUserTransaction(user);
request.setAttribute("result", result );
request.getRequestDispatcher("finance.jsp").forward(request, response);

我必须如何纠正这个问题，或者告诉我在哪里可以阅读这个内容？

Answer 1

我找到了这个问题的解决方案。正确的查询

select b from Categorietype c, Balance b  where c.user = :user and b.user = :user

并在jsp页面上将$ {r.name}更改为r.typecategory.sum

<table border="1">

  <tr>
    <th>Sum</th>
    <th>Descrip</th>
    <th>Name</th>
  </tr>
<c:forEach items="${result}" var="r">
  <tr>
    <td> ${r.sum} </td>
    <td> ${r.descrip} </td>
    <td> ${r.typecategory.name} </td>
  </tr>
</c:forEach>
</table>

<强> PS 我将查询更改为

select b.id as id, b.sum, b.description, t.name from Balance b join b.typecategory t where b.user = :user and b.typecategory = t and b.status = :status

更正确

在一个查询中将数据从2个表传输到jsp

1 个答案: