Question

我目前正在开展一个小组项目，我们应该处理建筑和房间之间的关系。关系是OnetoMany，我们现在能够显示sql中的相关数据，但是我们无法按照预期在一个外观漂亮的电子表格或表格中显示它。我们希望将建筑物和房间分成一张桌子，每个房间都显示与相关建筑物的连接。我们如何将我们的HTML代码放入我们的（ShowRooms.jsp）jsp中以获取用户构建选择的所有房间，然后在一个漂亮的桌子中显示该建筑物的所有房间？在这种状态下，我们从我们的sql-database获取数据，但只是在一条直线上，而不是通过将每个房间连接到相关建筑物的表。提前致谢！

这是我们的代码：BUILDING：

@Entity
@Table(name = "Building")
public class Building {
private String bname;
private List<Room> rooms; // Building can have many Rooms

@Id
@Column(name = "Bname")
public String getBname() {
return bname;
}

public void setBname(String bname) {
this.bname = bname;
}

@OneToMany(mappedBy = "building", fetch = FetchType.EAGER)
public List<Room> getRooms() {
return rooms;
}

public void setRooms(List<Room> rooms) {
this.rooms = rooms;
}   
}

房间：

@NamedQueries({
@NamedQuery(name="Room.findByBname",
query="SELECT r FROM Room r WHERE r.bname LIKE :bname"),
})

@Entity
@Table(name = "Room")
public class Room implements Serializable {
/**
* 
*/
private static final long serialVersionUID = 1L;
private RoomId id;
private String bname;
private Building building;

public String getBname() {
return bname;
}

public void setBname(String bname) {
this.bname = bname;
}

@Id
public RoomId getId() {
return id;
}

public void setId(RoomId id) {
this.id = id;
}

@ManyToOne
@JoinColumn(name = "Bname", insertable = false, updatable = false)
public Building getBuilding() {
return this.building;
}

public void setBuilding(Building building) {
this.building = building;
}
}

ROOMID:

@Embeddable
public class RoomId implements Serializable {

private String bname;
private String rcode;

public RoomId() {
}

public RoomId(String bname, String rcode) {
this.bname = bname;
this.rcode = rcode;
}

@Column(name = "Bname", nullable = false)
public String getbname() {
return bname;
}

public void setbname(String bname) {
this.bname = bname;
}

@Column(name = "Rcode", nullable = false)
public String getrcode() {
return rcode;
}

public void setrcode(String rcode) {
this.rcode = rcode;
}

public boolean equals(Object other) {
if ((this == other)) {
    return true;
}

if ((other == null)) {
    return false;
}

if (!(other instanceof RoomId)) {
    return false;
}

RoomId castOther = (RoomId) other;

return ((this.getbname() == castOther.getbname()) || (this.getbname() != null
        && castOther.getbname() != null &&

this.getbname().equals(castOther.getbname())))

        &&

((this.getrcode() == castOther.getrcode()) ||                                              (this.getrcode() != null               && castOther.getrcode() != null &&

        this.getrcode().equals(castOther.getrcode())));
}

public int hashCode() {
return super.hashCode();
}
}

BUILDINGEAO：

@Stateless
public class BuildingEAOImpl implements BuildingEAOImplLocal {
@PersistenceContext(unitName = "LabEJBSql")
private EntityManager em;

public BuildingEAOImpl() {
// TODO Auto-generated constructor stub
}

public Building findByBname(String bname) {
return em.find(Building.class, bname);
}
}

FACADE：

@Stateless
public class Facade implements FacadeRemote, FacadeLocal {
@EJB
BuildingEAOImplLocal BuildingEAO;
@EJB
RoomEAOImplLocal RoomEAO;

public Facade() {
// TODO Auto-generated constructor stub
}

public List<Room> findRoomsByBname(String bname) { 
 return RoomEAO.findByBname(bname); 
 }
}

SERVLET：

@WebServlet("/TestClientServlet")
public class TestClientServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@EJB
private FacadeLocal facade;

/**
* @see HttpServlet#HttpServlet()
*/
public TestClientServlet() {
super();
// TODO Auto-generated constructor stub
}

protected void doGet(HttpServletRequest request,
    HttpServletResponse response) throws ServletException, IOException {

PrintWriter out = response.getWriter();
out.println("TestClientServlet-doGet");
out.close();

}

protected void doPost(HttpServletRequest request,
    HttpServletResponse response) throws ServletException, IOException {

String url = null;
// Get hidden field
String operation = request.getParameter("operation");

if (operation.equals("showrooms")) {
    String bname = request.getParameter("txtBname");

    List<Room> r = facade.findRoomsByBname(bname);
    request.setAttribute("rooms", r);
    url = "/ShowRooms.jsp";
} else if (operation.equals("searchbuilding")) {
    System.out.println("TestClientServlet-searchbuilding");
    url = "/SearchBuilding.jsp";
} else {
    url = "/SearchBuilding.jsp";
}
System.out.println(url);

RequestDispatcher dispatcher = getServletContext()
        .getRequestDispatcher(url);
dispatcher.forward(request, response);
}
*/
}

SEARCHBUILDING.JSP：

<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=ISO-
8859-1"> 
<title>Search Building</title> 
</head> 
<body> 
<form action="/BuildRoomClientProject/TestClientServlet" method="post"> 

<table cellspacing="0" cellpadding="0" border="0" align="left"> 
<tr> 
<td><h2>Search Building:</h2></td> 
</tr> 
<tr> 
<td> 

<input type= "text" name= "txtBname" size ="25" maxlength="25">
<input type="submit" name="submit" value="Search" /> 
</td> 
<td></td> 
</tr> 
</table> 

<input name="operation" value="showrooms" type="hidden"> 

</form> 
</body> 
</html>

SHOWROOMS.JSP：

<%@ page contentType="text/html;charset=windows-1252"%> 
<%@ page import = "org.ics.ejb.Building" %> 
<%@ page import = "org.ics.ejb.Room" %> 
<%@ page import = "org.ics.ejb.RoomId" %> 
<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 
<title> 
Show Rooms
</title> 
</head> 
<body> 
<h2> 
Rooms: 
</h2> 
<%List<Room> r = (List<Room>)request.getAttribute("rooms"); %>
<% for (Room r1 : r){
out.println(r1.getBname() + " " + r1.getId().getrcode());
}%> 
<p>
</p>
<form action="/BuildRoomClientProject/TestClientServlet" method="post"> 
<input type="submit" name="submit" value="Tillbaka"> 
<input name="operation" value="searchbuilding" type="hidden"> 
</form> 
</body> 
</html>

Answer 1

对于你的jpql，你不能使用GROUPBY结合GROUPBY指令吗？然后，对于每个表项，您将获得bname（= BuildingName ??）作为第一行。然后将检索到的列表呈现为一个表，一个简短的例子可能是这样的：

<table>
     <c:forEach var="o" items="${objects}">
        <tr>
            <td>${o.bname}</td>
            <td>${o.id}</td>
            <td>${o.name}</td>
            <td>${o.descriptio}</td>   
        </tr>
    </c:forEach>
</table>

事实上，我刚刚发现：displaying a list of entities in jsp file by using java搜索“jsp，listview，table”

无法以正确的顺序显示SQL中的数据，HTML JSP

1 个答案: