创建一个web项目，然后生成HibernateSessionFactory文件！
package cn.bdqn.util; import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration; /**
* Configures and provides access to Hibernate sessions, tied to the
* current thread of execution. Follows the Thread Local Session
* pattern, see {@link http://hibernate.org/42.html }.
*/
public class HibernateSessionFactory { /**
* Location of hibernate.cfg.xml file.
* Location should be on the classpath as Hibernate uses
* #resourceAsStream style lookup for its configuration file.
* The default classpath location of the hibernate config file is
* in the default package. Use #setConfigFile() to update
* the location of the configuration file for the current session.
*/
private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
private static org.hibernate.SessionFactory sessionFactory; private static Configuration configuration = new Configuration();
private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
private static String configFile = CONFIG_FILE_LOCATION; static {
try {
configuration.configure(configFile);
sessionFactory = configuration.buildSessionFactory();
} catch (Exception e) {
System.err.println("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
}
private HibernateSessionFactory() {
} /**
* Returns the ThreadLocal Session instance. Lazy initialize
* the <code>SessionFactory</code> if needed.
*
* @return Session
* @throws HibernateException
*/
public static Session getSession() throws HibernateException {
Session session = (Session) threadLocal.get(); if (session == null || !session.isOpen()) {
if (sessionFactory == null) {
rebuildSessionFactory();
}
session = (sessionFactory != null) ? sessionFactory.openSession()
: null;
threadLocal.set(session);
} return session;
} /**
* Rebuild hibernate session factory
*
*/
public static void rebuildSessionFactory() {
try {
configuration.configure(configFile);
sessionFactory = configuration.buildSessionFactory();
} catch (Exception e) {
System.err.println("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
} /**
* Close the single hibernate session instance.
*
* @throws HibernateException
*/
public static void closeSession() throws HibernateException {
Session session = (Session) threadLocal.get();
threadLocal.set(null); if (session != null) {
session.close();
}
} /**
* return session factory
*
*/
public static org.hibernate.SessionFactory getSessionFactory() {
return sessionFactory;
} /**
* return session factory
*
* session factory will be rebuilded in the next call
*/
public static void setConfigFile(String configFile) {
HibernateSessionFactory.configFile = configFile;
sessionFactory = null;
}
/**
* return hibernate configuration
*
*/
public static Configuration getConfiguration() {
return configuration;
} }
在之前的基础上创建dao
public interface DistrictDao {
//根据制定的id查询区县信息 根据区县可以查询到街道
District getDistrictById(Integer id);
}
创建daoImpl
public class DistrictDaoImpl implements DistrictDao{
@Override
public District getDistrictById(Integer id) {
Session session = HibernateSessionFactory.getSession();
District district = (District) session.load(District.class, id);
System.out.println("daoImpl中的session=====>"+session.hashCode());
return district;
}
}
创建对应的servlet
public class DistrcitServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//实例化service层对象
DistrictDao dao=new DistrictDaoImpl();
//查询id是1001的区县下所有的街道
District district = dao.getDistrictById(1001);
List<Street> streets = district.getStreets();
//把街道放入指定的作用域
request.setAttribute("streets", streets);
request.getRequestDispatcher("index.jsp").forward(request, response);
}
}
创建对应的Filter 并在web.xml文件中配置filter和filter-mapping
public class OpenSessionInViewFilter implements Filter {
@Override
public void destroy() {
}
//真正执行代码的地方 获取session 开启事务
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
Session session = HibernateSessionFactory.getSession();
System.out.println("filter中的session=====>"+session.hashCode());
chain.doFilter(request, response);
HibernateSessionFactory.closeSession(); //关闭session
}
@Override
public void init(FilterConfig arg0) throws ServletException {
}
}
web.xml文件中新增
<filter>
<filter-name>openSession</filter-name>
<filter-class>cn.bdqn.filter.OpenSessionInViewFilter</filter-class>
</filter> <filter-mapping>
<filter-name>openSession</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
之后创建页面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head> <body>
<c:forEach items="${streets}" var="s">
${s.id }
${s.name } <br/>
</c:forEach>
</body>
</html>