*IntelliJ IDEA使用Hibernate连接数据库

在IntelliJ IDEA中配置MySQL Database.

Database是我们事先建立的数据库，对应我们的某一个项目.

添加Hibernate框架.

项目上右键->Add Framework Support.

Package是放置我们的实体类，一般是xx.xx.model就可以了.

生成的实体类已经包含了映射信息，所以不需要x.hbm.xml文件了.

@Entity
@Table(name = "users", schema = "mydb", catalog = "")
public class UsersEntity {
    private int id;
    private String name;
    private Byte age;

    @Id
    @Column(name = "id", nullable = false)
    public int getId() {
        return id;
    }

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

    @Basic
    @Column(name = "name", nullable = true, length = 100)
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Basic
    @Column(name = "age", nullable = true)
    public Byte getAge() {
        return age;
    }

    public void setAge(Byte age) {
        this.age = age;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        UsersEntity that = (UsersEntity) o;

        if (id != that.id) return false;
        if (name != null ? !name.equals(that.name) : that.name != null) return false;
        if (age != null ? !age.equals(that.age) : that.age != null) return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = id;
        result = 31 * result + (name != null ? name.hashCode() : 0);
        result = 31 * result + (age != null ? age.hashCode() : 0);
        return result;
    }
}

那么再来看看Hiebrnate的配置文件，注意，该配置文件不在正确的路径上。在WEB-INF下建立文件夹classes,放进去.

没有Driver的jar包.

拷贝到lib目录中，还没完，为什么呢？没有添加到Build Path中.看！前面都没有三角标记.

跟别人不一样嘛.

右键项目->Open Model Settings->Libraries.

要注意关注Problems.

系统为我们生成了数据库连接的代码

public class Main {
    private static final SessionFactory ourSessionFactory;
    private static final ServiceRegistry serviceRegistry;

    static {
        try {
            Configuration configuration = new Configuration();
            configuration.configure();

            serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
            ourSessionFactory = configuration.buildSessionFactory(serviceRegistry);
        } catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static Session getSession() throws HibernateException {
        return ourSessionFactory.openSession();
    }

    public static void main(final String[] args) throws Exception {
        final Session session = getSession();
        try {
            System.out.println("querying all the managed entities...");
            final Map metadataMap = session.getSessionFactory().getAllClassMetadata();
            for (Object key : metadataMap.keySet()) {
                final ClassMetadata classMetadata = (ClassMetadata) metadataMap.get(key);
                final String entityName = classMetadata.getEntityName();
                final Query query = session.createQuery("from " + entityName);
                System.out.println("executing: " + query.getQueryString());
                for (Object o : query.list()) {
                    System.out.println("  " + o);
                }
            }
        } finally {
            session.close();
        }
    }
}

新建目录db,将Main类改名成DbConnections.

获取数据库中的数据

@Controller
@RequestMapping("/users")
public class UserController {

    @RequestMapping(value = "/list.do", method = RequestMethod.GET)
    public String listUsers(ModelMap map) {
        Session session = DbConnections.getSession();
        List<UsersEntity> list = session.createCriteria(UsersEntity.class).list();
        map.addAttribute("users", list);
        session.close();
        return "users";
    }
}

doc + Alt + /:生成html模板，Alt + /需要自己配置.

<%@ page import="com.winner.db.entities.UsersEntity" %>
<%@ page import="java.util.List" %>
<%@ page pageEncoding="utf-8" %>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
<ol>
    <%for (UsersEntity e:(List<UsersEntity>)request.getAttribute("users")){%>
        <li>名字：<%out.println(e.getName());%>，年龄：<%out.println(e.getAge());%></li>
    <%}%>
</ol>
</body>
</html>

向数据库中添加用户：

@Controller
@RequestMapping("/users")
public class UserController {

    @RequestMapping(value = "/list.do", method = RequestMethod.GET)
    public String listUsers(ModelMap map) {
        Session session = DbConnections.getSession();
        List<UsersEntity> list = session.createCriteria(UsersEntity.class).addOrder(Order.desc("id")).list();
        map.addAttribute("users", list);
        session.close();
        return "users";
    }

    @RequestMapping(value = "/add.do", method = RequestMethod.GET)
    public String addUser() {
        return "add_user";
    }

    @RequestMapping(value = "/result.do", method = RequestMethod.GET)
    public String result(ModelMap map, String name, int age) {
        map.addAttribute("name", name);
        map.addAttribute("age", age);
        Session session = DbConnections.getSession();
        Transaction transaction = session.beginTransaction();
        UsersEntity ue = new UsersEntity();
        ue.setName(name);
        ue.setAge((byte) age);
        session.save(ue);
        transaction.commit();
        session.close();
        return "redirect:list.do";
    }
}

<%@ page pageEncoding="utf-8" %>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <form action="/users/result.do" method="get" >
        名字：<input type="text" name="name"/>
        年龄：<input type="text" name="age">
        <input type="submit" value="submit"/>
    </form>
</body>
</html>