作为一个Spring MVC新手最基本的功夫就是学会如何使用开发工具创建一个完整的Spring MVC项目，本文站在一个新手的角度讲述如何一步一步创建一个基于Spring MVC, Hibernate, My SQL的Maven项目。
本项目的目的：
- 学习如何创建并配置一个基于maven的Spring MVC项目
- 学习如何映射数据表到对象
- 学习如何使用Hibernate操纵数据库数据
- 学习如何使用拦截器过滤未授权的访问
因为在使用不同的IDEA 版本、不同的Spring MVC版本或者不同Hibernate版本创建项目的时候创建方式和配置都有可能一些不一样，下面列出本文所使用的各个组件的版本，如果你所使用的版本和我的不一样，请灵活做出改变～
- JDK: 1.8
- IDEA Ultimate: 2016
- Spring MVC: 4.3.3
- Hibernate: 5.2.3
创建一个基于Maven的Webapp项目
- 新建一个项目：Maven -> Create from archetype -> org.apache.maven.archetypes:maven-archetype-webapp
注意别一不小心选择了org.apche.cocoon:cocoon-22-archetype-webapp
- 下一步主要是需要输入项目的GroupId和ArtifactId，比较简单就不上图了。
- 下下一步也没有什么特别要设置的，可以直接再下一步。
- 点击完成后需要稍微等一下，因为要根据Webapp框架下载一些依赖包和创建项目索引，耐心等个一两分钟，一个基础的Webapp项目就创建好了。
新建一个运行配置
- Running -> Edit Configurations...
- 在Deployment选项卡里添加一个Artifacts：
- 全部的运行配置如下：
配置好了之后，点击那个三角按钮运行，哈哈～Hello World! 出来了。
至此一个基本的web项目已经创建好并可以运行。
创建数据库
在这里我使用的是My SQL数据库，只创建一个表用于存放用户信息，里面只有三个字段：
CREATE DATABASE demo;
USE demo;
CREATE TABLE user_info
(
id INT(11) PRIMARY KEY NOT NULL AUTO_INCREMENT,
user_name VARCHAR(100) NOT NULL,
password VARCHAR(100) NOT NULL
);
CREATE UNIQUE INDEX table_name_id_uindex ON user_info (id);
INSERT INTO user_info (user_name, password) VALUES ("admin", "admin");
创建Spring MVC目录结构
打开Project Structure，创建如下图红框内的文件夹：
- java: 标记为Sources（从颜色可看出与其他文件夹的区别）
- controller: 控制器代码，主要是提供web接口。
- dao: 数据访问对象代码，用于操纵数据库。
- entity: 实体类代码，对应数据库表的映射。
- interceptor: 拦截器代码，比如可用用来拦截未经验证的请求。
- service: 业务层代码
- utils: 工具类代码
配置文件
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>maven-springmvc-hibernate-mysql-demo</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>maven-springmvc-hibernate-mysql-demo Maven Webapp</name>
<url>http://maven.apache.org</url> <dependencies>
<!-- Spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.2.release</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>4.3.2.release</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>4.3.2.release</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>4.3.2.RELEASE</version>
</dependency>
<!-- Hibernate -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.2.3.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>5.2.3.Final</version>
</dependency>
<!-- unit test -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<!-- log -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.6.1</version>
</dependency>
<!-- jstl -->
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!-- Apache Commons DBCP -->
<dependency>
<groupId>commons-dbcp</groupId>
<artifactId>commons-dbcp</artifactId>
<version>1.4</version>
</dependency>
<!-- tomcat servlet api -->
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-servlet-api</artifactId>
<version>7.0.53</version>
<scope>provided</scope>
</dependency>
<!-- MySql 5.5 Connector -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>6.0.4</version>
</dependency>
</dependencies> <build>
<finalName>maven-springmvc-hibernate-mysql-demo</finalName>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<!--JDK version-->
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
添加好pom文件后，点击刷新，过程中需要在线下载一些依赖包和创建索引，这中间可能需要等待较长时间，可以去泡杯茶喝先了。因为国内连接国外的Maven仓库超级不稳定，如果下载失败，请自行查找可用的Maven仓库并添加到Maven的settings.xml文件（推荐阿里云的仓库）。
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0"> <context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/applicationContext.xml</param-value>
</context-param> <listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener> <servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet> <servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping> </web-app>
添加配置文件：WEB-INF/applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd"> <annotation-driven/>
<context:component-scan base-package="com.demo.controller"/>
<tx:annotation-driven transaction-manager="transactionManager"/> <beans:bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<beans:property name="prefix" value="/WEB-INF/views/"/>
</beans:bean> <beans:bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
destroy-method="close">
<beans:property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<beans:property name="url"
value="jdbc:mysql://localhost:3306/demo"/>
<beans:property name="username" value="root"/>
<beans:property name="password" value="xxx"/>
</beans:bean> <!-- Hibernate 5 SessionFactory Bean definition -->
<beans:bean id="hibernate5AnnotatedSessionFactory"
class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
<beans:property name="dataSource" ref="dataSource"/>
<beans:property name="annotatedClasses">
<beans:list>
<beans:value>com.demo.entity.UserInfoEntity</beans:value>
</beans:list>
</beans:property>
<beans:property name="hibernateProperties">
<beans:props>
<beans:prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect
</beans:prop>
<beans:prop key="hibernate.show_sql">true</beans:prop>
</beans:props>
</beans:property>
</beans:bean> <beans:bean id="userInfoDao" class="com.demo.dao.UserInfoDaoImpl">
<beans:property name="sessionFactory" ref="hibernate5AnnotatedSessionFactory"/>
</beans:bean> <beans:bean id="userInfoService" class="com.demo.service.UserInfoServiceImpl">
<beans:property name="userInfoDao" ref="userInfoDao"></beans:property>
</beans:bean> <beans:bean id="transactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager">
<beans:property name="sessionFactory" ref="hibernate5AnnotatedSessionFactory"/>
</beans:bean> <mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/index"/>
<mvc:mapping path="/user/**"/>
<beans:bean class="com.demo.interceptor.LoginInterceptor"/>
</mvc:interceptor>
</mvc:interceptors> </beans:beans>
需改bean "dataSource" 中的My SQL配置，把IP、用户名、密码修改为你相应的值。
添加配置文件：WEB-INF/dispatcher-servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> </beans>
前端文件
- 把系统自动生成的index.jsp删除掉。
- 在/webapp/WEB-INF下创建views文件夹，然后分别创建一下两个文件：
login.jsp
<%--
User: keitsi
Date: 16-10-22
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>User Login</title>
</head>
<body>
<form action="/authenticate" method="post">
<div>
<label for="user_name">User Name: </label>
<input id="user_name" name="userName" type="text">
</div>
<div>
<label for="password">Password: </label>
<input id="password" name="password" type="password">
</div>
<div>
<input type="submit" value="submit">
</div>
<p style="color: red;"><%=request.getParameter("errorMessage") == null ? "" : request.getParameter("errorMessage")%>
</p>
</form>
</body>
</html>
user_list.jsp
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
<head>
<title>User Page</title>
<style type="text/css">
.tg {
border-collapse: collapse;
border-spacing: 0;
border-color: #ccc;
} .tg td {
padding: 10px 5px;
border: solid 1px #ccc;
text-align: center;
} .tg th {
border: solid 1px #ccc;
background-color: #f0f0f0;
padding: 10px 5px;
}
</style>
</head>
<body>
<h3>Hello ${LoginUser.userName} <a href="/user/logout">Logout</a></h3> <br> <h3>
Modify User
</h3> <c:url var="addAction" value="/user/modify"></c:url> <form action="${addAction}" method="post">
<table>
<c:if test="${!empty user.userName}">
<tr>
<td>
<label for="id">ID: </label>
</td>
<td>
<input id="id" name="id" value="${user.id}">
</td>
</tr>
</c:if>
<tr>
<td>
<label for="user_name">User Name: </label>
</td>
<td>
<input id="user_name" name="userName" value="${user.userName}">
</td>
</tr>
<tr>
<td>
<label for="password">Password: </label>
</td>
<td>
<input id="password" name="password" value="${user.password}">
</td>
</tr>
<tr>
<td colspan="2">
<c:if test="${!empty user.userName}">
<input type="submit" value="Edit Person"/>
</c:if>
<c:if test="${empty user.userName}">
<input type="submit" value="Add Person"/>
</c:if>
</td>
</tr>
</table>
</form> <br> <h3>User List</h3>
<c:if test="${!empty allUsers}">
<table class="tg">
<tr>
<th width="80">User ID</th>
<th width="120">User Name</th>
<th width="120">Password</th>
<th width="60">Edit</th>
<th width="60">Delete</th>
</tr>
<c:forEach items="${allUsers}" var="user">
<tr>
<td>${user.id}</td>
<td>${user.userName}</td>
<td>${user.password}</td>
<td><a href="<c:url value='/user/edit/${user.id}' />">Edit</a></td>
<td><a href="<c:url value='/user/remove/${user.id}' />">Delete</a></td>
</tr>
</c:forEach>
</table>
</c:if>
</body>
</html>
数据库访问层
entity/UserInfoEntity.java
package com.demo.entity; import javax.persistence.*; /**
* Created by keitsi on 16-10-21.
*/
@Entity
@Table(name = "user_info", schema = "demo")
public class UserInfoEntity {
private int id;
private String userName;
private String password; @Id
@Column(name = "id")
public int getId() {
return id;
} public void setId(int id) {
this.id = id;
} @Basic
@Column(name = "user_name")
public String getUserName() {
return userName;
} public void setUserName(String userName) {
this.userName = userName;
} @Basic
@Column(name = "password")
public String getPassword() {
return password;
} public void setPassword(String password) {
this.password = password;
} @Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false; UserInfoEntity that = (UserInfoEntity) o; if (id != that.id) return false;
if (userName != null ? !userName.equals(that.userName) : that.userName != null) return false;
if (password != null ? !password.equals(that.password) : that.password != null) return false; return true;
} @Override
public int hashCode() {
int result = id;
result = 31 * result + (userName != null ? userName.hashCode() : 0);
result = 31 * result + (password != null ? password.hashCode() : 0);
return result;
}
}
dao/UserInfoDao.java
package com.demo.dao; /**
* Created by keitsi on 16-10-21.
*/ import com.demo.entity.UserInfoEntity; import java.util.List; public interface UserInfoDao { void add(UserInfoEntity p); void update(UserInfoEntity p); void remove(int id); List<UserInfoEntity> getAll(); UserInfoEntity getById(int id); UserInfoEntity getByName(String name); }
dao/UserInfoDaoImpl.java
package com.demo.dao; /**
* Created by keitsi on 16-10-21.
*/ import com.demo.entity.UserInfoEntity;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.query.Query;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Repository; import java.util.List; @Repository
public class UserInfoDaoImpl implements UserInfoDao { private static final Logger logger = LoggerFactory.getLogger(UserInfoDaoImpl.class); private SessionFactory sessionFactory; public void setSessionFactory(SessionFactory sf) {
this.sessionFactory = sf;
} public void add(UserInfoEntity user) {
Session session = this.sessionFactory.getCurrentSession();
session.persist(user);
logger.info("Person saved successfully, Person Details=" + user);
} public void update(UserInfoEntity user) {
Session session = this.sessionFactory.getCurrentSession();
session.update(user);
logger.info("Person updated successfully, Person Details=" + user);
} public void remove(int id) {
Session session = this.sessionFactory.getCurrentSession();
UserInfoEntity user = (UserInfoEntity) session.load(UserInfoEntity.class, new Integer(id));
if (null != user) {
session.delete(user);
}
logger.info("Person deleted successfully, person details=" + user);
} @SuppressWarnings("unchecked")
public List<UserInfoEntity> getAll() {
Session session = this.sessionFactory.getCurrentSession();
List<UserInfoEntity> userList = session.createQuery("from UserInfoEntity ").list();
for (UserInfoEntity user : userList) {
logger.info("Person List::" + user);
}
return userList;
} public UserInfoEntity getById(int id)
{
Session session = this.sessionFactory.getCurrentSession();
UserInfoEntity user = (UserInfoEntity) session.load(UserInfoEntity.class, new Integer(id));
logger.info("Person loaded successfully, Person details=" + user);
return user;
} public UserInfoEntity getByName(String name){
Session session = this.sessionFactory.getCurrentSession();
Query query = session.createQuery("from UserInfoEntity where userName = :userName ");
query.setParameter("userName", name);
List list = query.list();
if (list.size()>0){
return (UserInfoEntity) list.get(0);
}else {
return null;
}
} }
业务层代码
service/UserInfoService.java
package com.demo.service; /**
* Created by keitsi on 16-10-21.
*/ import com.demo.entity.UserInfoEntity; import java.util.List; public interface UserInfoService { void add(UserInfoEntity p); void update(UserInfoEntity p); void remove(int id); List<UserInfoEntity> getAll(); UserInfoEntity getById(int id); UserInfoEntity getByName(String name);
}
service/UserInfoServiceImpl.java
package com.demo.service; /**
* Created by keitsi on 16-10-21.
*/ import com.demo.dao.UserInfoDao;
import com.demo.entity.UserInfoEntity;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional; import javax.annotation.Resource;
import java.util.List; @Service
public class UserInfoServiceImpl implements UserInfoService { @Resource
private UserInfoDao userInfoDao; public void setUserInfoDao(UserInfoDao userInfoDao) {
this.userInfoDao = userInfoDao;
} @Transactional
public void add(UserInfoEntity user) {
this.userInfoDao.add(user);
} @Transactional
public void update(UserInfoEntity user) {
this.userInfoDao.update(user);
} @Transactional
public void remove(int id) {
this.userInfoDao.remove(id);
} @Transactional
public List<UserInfoEntity> getAll() {
return this.userInfoDao.getAll();
} @Transactional
public UserInfoEntity getById(int id) {
return this.userInfoDao.getById(id);
} @Transactional
public UserInfoEntity getByName(String name)
{
return this.userInfoDao.getByName(name);
} }
控制器层代码
controller/RootController.java
package com.demo.controller; import com.demo.entity.UserInfoEntity;
import com.demo.service.UserInfoService;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod; import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; /**
* Created by keitsi on 16-10-22.
*/
@Controller
@RequestMapping("")
public class RootController {
@Resource
private UserInfoService userService; @RequestMapping("")
public String root() {
return "redirect:/index";
} @RequestMapping("/index")
public String index() {
return "redirect:/user/list.jsp";
} @RequestMapping("/login")
public String login() {
return "/login.jsp";
} @RequestMapping(value = "/authenticate", method = RequestMethod.POST)
public void login(HttpServletRequest request, HttpServletResponse response, String userName, String password) throws Exception {
UserInfoEntity user = userService.getByName(userName);
if (user.getPassword().equals(password)) {
request.getSession().setAttribute("LoginUser", user);
response.sendRedirect(request.getContextPath() + "/user/list");
} else {
response.sendRedirect(request.getContextPath() + "/login?errorMessage=User name or password is not correct.");
}
}
}
controller/UserController.java
package com.demo.controller; /**
* Created by keitsi on 16-10-21.
*/ import com.demo.entity.UserInfoEntity;
import com.demo.service.UserInfoService;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod; import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; @Controller
@RequestMapping("/user")
public class UserController {
@Resource
private UserInfoService userService; @RequestMapping(value = "/list", method = RequestMethod.GET)
public String listUsers(HttpServletRequest request, Model model) {
UserInfoEntity loginUser = (UserInfoEntity)request.getSession().getAttribute("LoginUser");
model.addAttribute("LoginUser", loginUser);
model.addAttribute("user", new UserInfoEntity());
model.addAttribute("allUsers", this.userService.getAll());
return "/user_list.jsp";
} @RequestMapping(value = "/logout", method = RequestMethod.GET)
public void logout(HttpServletRequest request, HttpServletResponse response, String userName, String password) throws Exception {
request.getSession().setAttribute("LoginUser", null);
response.sendRedirect(request.getContextPath() + "/index");
} //For add and update person both
@RequestMapping(value = "/modify", method = RequestMethod.POST)
public String addPerson(@ModelAttribute("user") UserInfoEntity user) { if (user.getId() == 0) {
//new person, add it
this.userService.add(user);
} else {
//existing person, call update
this.userService.update(user);
}
return "redirect:/user/list";
} @RequestMapping("/edit/{id}")
public String editPerson(HttpServletRequest request, @PathVariable("id") int id, Model model) {
UserInfoEntity loginUser = (UserInfoEntity)request.getSession().getAttribute("LoginUser");
model.addAttribute("LoginUser", loginUser);
model.addAttribute("user", this.userService.getById(id));
model.addAttribute("allUsers", this.userService.getAll());
return "/user_list.jsp";
} @RequestMapping("/remove/{id}")
public String removePerson(@PathVariable("id") int id) {
this.userService.remove(id);
return "redirect:/user/list";
} }
拦截器层代码
interceptor/LoginInterceptor.java
package com.demo.interceptor; import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView; import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; /**
* Created by keitsi on 16-10-22.
*/
public class LoginInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
Object loginUser = request.getSession().getAttribute("LoginUser");
if(loginUser == null){
response.sendRedirect(request.getContextPath() + "/login");
return false;
}
return loginUser != null;
} public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
throws Exception {
} public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
}
}
运行
点击运行，在启动tomcat的时候有可能会遇到如下图所示的运行异常：
严重: Error configuring application listener of class org.springframework.web.context.ContextLoaderListener
java.lang.ClassNotFoundException: org.springframework.web.context.ContextLoaderListener
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1891)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1734)
at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:504)
at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:486)
这是因为我们的打包的war包里面没有自动加入Spring MVC的jar包，所以只需要把依赖的jar包添加到输出目录即可：
File -> Project Structure... -> Artifacts
在Available Elements的根节点点击右键 -> Put into Out Root
再次点击运行，如果不出什么故障你就能看到下面的登录界面：
用户名和密码都是：admin
页面比较简单，因为没有加入太多的样式。
登录之后的界面：
是一个用户管理界面，覆盖了对数据库的：增、删、改、查
项目代码：https://github.com/keitsi/maven-springmvc-hibernate-mysql-demo