如何使用Hibernate从多个表查询中获取数据？

我正在开发一个使用Spring的简单应用程序& Hibernate。 IDE：Eclipse如何使用Hibernate从多个表查询中获取数据？

我想显示学生的时间表。

时间表使用学生，科目，考试，&班级表。

附表包含：学生姓名，卷号，科目，班级，考试，时间，到时间&日期。

我已经写了一个查询（与> 1表一起工作），这将返回我一个记录，&这条记录将按计划显示。

查询没有问题（我在控制台上打印了对象）。

我得到一个NumberFormatException异常对我的.jsp而从列表中检索记录（列表是从控制器发送）

1）它是检索从JSP列表中的多个表中的值正确的方式？如果这个错误，请建议正确的方法。

2）任何其他下列代码的任何部分的变化，这将能够满足我的需求??

3）任何其他方式做同样的事情.. ??

例外：

exception 

org.apache.jasper.JasperException: An exception occurred processing JSP page /pages/studentschedule.jsp at line 301 

298:    </tr> 
299:    <c:forEach items="${scheduleList}" var="var"> 
300:    <tr> 
301:     <td><b>${var.firstname }</b></td> 
302:     <td><b>${var.roll }</b></td> 
303:     <td><b>${var.subjectname }</b></td> 
304:     <td><b>${var.classname }</b></td> 


Stacktrace: 
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568) 
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470) 
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) 
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238) 
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:262) 
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1265) 
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1016) 
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:965) 
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:859) 
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:883) 
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:781) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:621) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 

root cause 

java.lang.NumberFormatException: For input string: "firstname" 
java.lang.NumberFormatException.forInputString(Unknown Source) 
java.lang.Integer.parseInt(Unknown Source) 
java.lang.Integer.parseInt(Unknown Source) 
javax.el.ArrayELResolver.coerce(ArrayELResolver.java:166) 
javax.el.ArrayELResolver.getValue(ArrayELResolver.java:46) 
javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67) 
org.apache.el.parser.AstValue.getValue(AstValue.java:169) 
org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189) 
org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:985) 
org.apache.jsp.pages.studentschedule_jsp._jspx_meth_c_005fforEach_005f0(studentschedule_jsp.java:459) 
org.apache.jsp.pages.studentschedule_jsp._jspService(studentschedule_jsp.java:364) 
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432) 
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) 
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238) 
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:262) 
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1265) 
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1016) 
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:965) 
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:859) 
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:883) 
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:781) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:621) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.25 logs.

查询+代码如下。

AdminStudentDaoImpl.java

@Override 
public List<Student> getStudentSchedule(int a) { 
    // TODO Auto-generated method stub 

    List<Student> u=hibernatetemplate.find("select stud.firstname,stud.roll,sub.subjectname,cls.classname,exam.exam_name,exam.from_time,exam.to_time,exam.exam_date from Student stud,Subject sub,Classs cls,Exam exam where exam.classs=cls.id and exam.subject=sub.id and sub.classs=cls.id and stud.classs=cls.id and stud.roll="+a); 

    return u; 
}

域（表）如下：

学生

@Entity 
@Table(name="student") 
public class Student { 

@Id 
@GeneratedValue 
@Column(name="id") 
private int id; 
@Column(name="roll_no") 
private int roll; 
@Column(name="firstname") 
private String firstname; 
@Column(name="lastname") 
private String lastname; 
@Column(name="dob") 
private String dob; 
@Column(name="email") 
private String email; 
@Column(name="contactno") 
private String contactno; 
@ManyToOne 
private Classs classs; 

    Getters & Setters....... 
    }

类

@Entity 
@Table(name="class") 

public class Classs { 

@Id 
@GeneratedValue 
@Column(name="id") 
private int id; 
    @Column(name="classname") 
private String classname; 
    Getters & Setters..... 
}

考试

@Entity 
@Table(name="exam") 
public class Exam { 

@Id 
@GeneratedValue 
@Column(name="id") 
private int id; 
@Column(name="exam_name") 
private String exam_name; 

@Column(name="exam_date") 
private String exam_date; 

@Column(name="from_time") 
private String from_time; 

@Column(name="to_time") 
private String to_time; 

@ManyToOne 
private Subject subject; 

@ManyToOne 
private Classs classs; 

    Getters & Setters..... 
}

主题

@Entity 
@Table(name="subject") 
public class Subject { 

    @Id 
    @GeneratedValue 

    @Column(name="id") 
    private int id; 

    @Column(name="subjectname") 
    private String subjectname; 

    @ManyToOne 
    private Classs classs; 

      Getters & Setters..... 
}

在控制器我写了这样的代码：

@RequestMapping(value="schedule" ,method=RequestMethod.GET) 
public ModelAndView schedule(@ModelAttribute("attribute") Student student,BindingResult result,HttpSession session)throws Exception 
{ 
    int roll=Integer.parseInt((String) session.getAttribute("username")); 
    System.out.println("roll no is========="+roll); 
    List<Student> stud = adminstudentdao.getStudentSchedule(roll); 
    System.out.println("list is========="+stud); 
    ModelMap map=new ModelMap(); 
    map.addAttribute("scheduleList",stud); 
    return new ModelAndView("studentschedule",map); 
}

jsp的：

<table border="0" width="100%" cellpadding="0" cellspacing="0" id="schedule-table"> 
      <tr> 

       <th class="table-header-repeat line-left minwidth-1"><a href="">Student name</th> 
       <th class="table-header-repeat line-left minwidth-1"><a href="">Roll number</th> 
       <th class="table-header-repeat line-left minwidth-1"><a href="">Subject</th> 
       <th class="table-header-repeat line-left minwidth-1"><a href="">Class</th> 
       <th class="table-header-repeat line-left minwidth-1"><a href="">exam</a></th> 
       <th class="table-header-repeat line-left minwidth-1"><a href="">from time</th> 
       <th class="table-header-repeat line-left minwidth-1"><a href="">to time</th> 
       <th class="table-header-repeat line-left minwidth-1"><a href="">date</th> 

      </tr> 
      <c:if test="${empty scheduleList}"> 
        <tr> 
         <td colspan="8"><b>No Results found</b></td> 
        </tr> 
      </c:if> 
      <c:forEach items="${scheduleList}" var="var"> 
      <tr> 
       <td><b>${var.firstname }</b></td> 
       <td><b>${var.roll }</b></td> 
       <td><b>${var.subjectname }</b></td> 
       <td><b>${var.classname }</b></td> 
       <td><b>${var.exam_name }</b></td> 
       <td><b>${var.from_time }</b></td> 
       <td><b>${var.to_time }</b></td> 
       <td><b>${var.exam_date }</b></td> 


      </tr> 
      </c:forEach> 

      </table>

来源

2013-06-03 Rohhit

我建议你使用Hibernate的母语SQL。为此，您可以修改您的AdminStudentDaoImpl。Java来：

public List getStudentSchedule(int a) { 
    Session sessionHb = session.openSession(); 
    String sql = "select stud.firstname,stud.roll,sub.subjectname,cls.classname,exam.exam_name,exam.from_time,exam.to_time,exam.exam_date from Student stud,Subject sub,Classs cls,Exam exam where exam.classs=cls.id and exam.subject=sub.id and sub.classs=cls.id and stud.classs=cls.id and stud.roll= :roll"; 
    SQLQuery query = sessionHb.createSQLQuery(sql); 
    query.setParameter("roll", a); 
    query.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP); 
    return query.list(); 
}

我希望这将有助于:)

来源

2013-06-06 13:48:48

谢谢纳比勒......它的工作... – Rohhit

为你高兴。欢迎您:) –

如何迭代这个列表从这个方法返回？正如在此列表中存在多个实体一样。 – VJS

如何使用Hibernate从多个表查询中获取数据？

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