Question

我正在使用Java Spring框架开发网站。这是一个互联网论坛。现在，登录后，我想列出当前存储在我的数据库中的所有线程。我将首先向您介绍我实施的重要部分。帖子很长，但不要气馁，这真的是一个简单的基本问题，任何具有网络编程基础经验的人都可以立即解决。我向你保证。

Thread对象由其自己的Thread类定义。它是一个标准的Entity类，包含一些字段，构造函数和getter / setter。

@Entity
public class Thread {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    int _id;

    private Date last_modified;
    private int topics;
    private String description;
    private String name;

    public Thread(){

    }



    public Thread(int _id, Date last_modified, int topics, String description,
            String name) {
        super();
        this._id = _id;
        this.last_modified = last_modified;
        this.topics = topics;
        this.description = description;
        this.name = name;
    }



    public int getId() {
        return _id;
    }
    public void setId(int _id) {
        this._id = _id;
    }
    public Date getLast_modified() {
        return last_modified;
    }
    public void setLast_modified(Date last_modified) {
        this.last_modified = last_modified;
    }
    public int getTopics() {
        return topics;
    }
    public void setTopics(int topics) {
        this.topics = topics;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

}

现在，转到下一层，我在DAO包中有相应的DAO接口：

@Transactional(propagation = Propagation.REQUIRED)
public interface ThreadDAO {

    public void addThread(Thread thread);
    public List<Thread> listThread();
    public void removeThread (int id);
    public void editThread(Thread thread);


}

及其实施：

@Repository("threadDao")
@Transactional
public class ThreadDAOImpl implements ThreadDAO{

    @Autowired
    SessionFactory sessionFactory;



    @Override
    public void addThread(Thread thread) {
        // TODO Auto-generated method stub
        sessionFactory.getCurrentSession().save(thread);    
    }

    @Override
    public List<Thread> listThread() {
        // TODO Auto-generated method stub
        return sessionFactory.getCurrentSession().createQuery("from Thread order by _id").list();
    }

    @Override
    public void removeThread(int id) {
        // TODO Auto-generated method stub
         Thread thread = (Thread) sessionFactory.getCurrentSession().load(
                    Thread.class, id);
            if (null != thread) {
                sessionFactory.getCurrentSession().delete(thread);
            }
    }

    @Override
    public void editThread(Thread thread) {
        // TODO Auto-generated method stub
        sessionFactory.getCurrentSession().update(thread);
    }

}

为了将数据推送到我的控制器，我使用自动服务：

@Transactional(propagation = Propagation.REQUIRED)
public interface ThreadService {

    public void addThread(Thread thread);
    public List<Thread> listThread();
    public void removeThread (int id);
    public void editThread(Thread thread);


}

实现：

@Service("threadService")
@Transactional
public class ThreadServiceImpl implements ThreadService{


    @Autowired
    ThreadDAO threadDAO;

    @Override
    public void addThread(Thread thread) {
        // TODO Auto-generated method stub
        threadDAO.addThread(thread);
    }

    @Override
    public List<Thread> listThread() {
        // TODO Auto-generated method stub
        return threadDAO.listThread();
    }

    @Override
    public void removeThread(int id) {
        // TODO Auto-generated method stub
        threadDAO.removeThread(id);
    }

    @Override
    public void editThread(Thread thread) {
        // TODO Auto-generated method stub
        threadDAO.editThread(thread);
    }

}

最后，我应该在控制器中执行Service方法：

@Controller
public class LoginController {

    @Autowired
    UserService userService;

    @Autowired
    ThreadService threadService;

    @RequestMapping(value = "/login", method = RequestMethod.GET)
    public ModelAndView login(
        @RequestParam(value = "error", required = false) String error,
        @RequestParam(value = "logout", required = false) String logout) {

        ModelAndView model = new ModelAndView();
        if (error != null) {
            model.addObject("error", "Invalid username and password!");
        }

        if (logout != null) {
            model.addObject("msg", "You've been logged out successfully.");
        }
        model.setViewName("login");

        return model;

    }



    @RequestMapping(value = "/standard", method = RequestMethod.GET)
    public ModelAndView standardView() 
    {

        ModelAndView model = new ModelAndView();
        model.setViewName("standard");
        return model; 

    }
}

那就是我的问题开始的地方。因为我在网络编程方面总体上很糟糕，而且请求映射的概念对我来说一直很混乱。标准＆＃39; layout现在包含用户登录的信息，并显示它的用户名，另外我为我的线程添加了列表布局：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@taglib uri="http://www.springframework.org/tags" prefix="spring"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Access denied</title>
</head>
<body>
<!-- h1><spring:message code="access.denied"/></h1> -->
<h6>Logged in as: ${pageContext.request.userPrincipal.name}</h6>

<c:url value="/j_spring_security_logout" var="logoutUrl" />

    <!-- csrt for log out-->
    <form action="${logoutUrl}" method="post" id="logoutForm">
      <input type="hidden" 
        name="${_csrf.parameterName}"
        value="${_csrf.token}" />
    </form>
    <script>
        function formSubmit() {
            document.getElementById("logoutForm").submit();
        }
    </script>

<a href="javascript:formSubmit()"> Logout</a>

<h3><spring:message code="label.threadList"/></h3>
<c:if  test="${!empty threadList}">
<table class="data">
<tr>
    <th><spring:message code="label.threadName"/></th>
     <th><spring:message code="label.threadDescription"/></th>
    <th><spring:message code="label.threadTopicCount"/></th>
    <th><spring:message code="label.threadLastModified"/></th>

</tr>
<c:forEach items="${threadList}" var="thread">
    <tr>
        <td>${thread.name} </td>
        <td>${thread.description} </td>
        <td>${thread.topics}</td>
        <td>${thread.last_modified}</td>

    </tr>
</c:forEach>
</table>

缺少的是控制器中的请求映射。我如何映射它，以便它传递线程条目，逐个记录，并在登录信息中以此布局显示它们？

Answer 1

只需将对象添加到控制器中的ModelAndView实例：

model.addObject("threadList", threadService.listThread());

它应该可以在JSP页面中访问。

另外请不要在DAO层上使用事务 - 只在服务层上使用它。请参阅this post。

使用Spring控制器从数据库中列出对象

1 个答案: