第二節 基於XML映射文件實現數據的CURD

基於XML映射文件實現數據的CURD

項目結構

1. configuration文件需要放在resources根目錄中。
2. **.hbm.xml文件要和實體類放在一起
3.

項目開發步驟

1. hibernate.cfg.xml
2. User.java
3. User.hbm.xml
4. UserDao.java
5. UserDaoImpl.java
6. UserDaoTest.java

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <!--hibernate鏈接的基本信息，數據庫信息-->
        <property name="connection.driver_class">org.postgresql.Driver</property>
        <property name="connection.url">jdbc:postgresql://localhost:5432/hibernate</property>
        <property name="connection.username">postgres</property>
        <property name="connection.password">123456</property>
        <!--hibernate方言-->
        <property name="dialect"> org.hibernate.dialect.PostgresPlusDialect</property>
        <!--是否打印sql-->
        <!--
            update，存在就修改，不存在就創建
            create，每次都刪除表然後再重新創建表
        -->
        <property name="hibernate.hbm2ddl.auto">update</property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        <!--hibernate映射文件-->
        <mapping  resource="cn/edu/scnu/xmlcurd/entity/User.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

<!--Hibernate 3.0 dtd-->

User.java

package cn.edu.scnu.xmlcurd.entity;

import java.text.SimpleDateFormat;
import java.util.Date;

public class User {
    private int id;
    private String username;
    private String password;
    private Date registerDate;

    public int getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Date getRegisterDate() {
        return registerDate;
    }

    public void setRegisterDate(Date registerDate) {
        this.registerDate = registerDate;
    }

    @Override
    public String toString() {
        return "UserEntity{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", registerDate=" +
                new SimpleDateFormat("yyyy-MM-dd").format(registerDate) +
                '}';
    }
}

User.hbm.xml

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!--
    **.hbm.xml應該和類名相同
-->
<hibernate-mapping package="cn.edu.scnu.xmlcurd">
    <!--
        class 中的name應該對應實體類的類名
        class 中的table應該對應數據庫表的名字
        class 中的catalog應該對應數據庫的名字
    -->
    <class name="cn.edu.scnu.xmlcurd.entity.User" table="users" catalog="hibernate">
        <!--
            每一個實體類都必須有一個id屬性
            generator:主鍵生成策略
                increment（hibernate遞增方式）,
                identity（蘇杭鉅款底層自增）,
                sequence（數據庫序列生成機制）,
                hilo（hibernate高低位算法生成）,
                native（自動識別數據庫）,
                assigned（應用程序產生），當不指定generator時，默認這種策略
        -->
        <id name="id" type="java.lang.Integer">
            <column name="id"/>
            <generator class="native"/>
        </id>
        <!--
            屬性中的name對應實體類中的屬性名
            屬性中的type對應實體類中屬性的類型
        -->
        <property name="username" type="java.lang.String">
            <column name="username" length="16" not-null="true"/>
        </property>
        <property name="password" type="java.lang.String">
            <column name="password" length="16" not-null="true"/>
        </property>
        <property name="registerDate" type="java.util.Date">
            <column name="registerDate" not-null="true"/>
        </property>

    </class>

</hibernate-mapping>

UserDao.java

package cn.edu.scnu.xmlcurd.dao;

import cn.edu.scnu.xmlcurd.entity.User;

import java.util.List;

public interface UserDao {
    void save(User user);
    void delete(Integer id);
    void update(User user,Integer id);
    User findById(Integer id);
    List<User> getAll();
}

UserDaoImpl.java

package cn.edu.scnu.xmlcurd.dao.impl;

import cn.edu.scnu.xmlcurd.dao.UserDao;
import cn.edu.scnu.xmlcurd.entity.User;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;

import java.util.ArrayList;
import java.util.List;

/*
具體流程：
    提供sessionFactory
    通過sessionFactory獲得session
    打開session
    開始transaction
 上面都是初始化
    事務開始
 下面都是結束
    提交transaction
    關閉session
    關閉sessionFactory
 */

/**
 * 注意：
 *      get方法獲取數據，如果數據不存在會返回null
 *      load方法獲取數據，如果數據不存在會出現ObjectNotFoundException異常，因此使用load方法時，數據必須存在
 */

public class UserDaoImpl implements UserDao {

    private SessionFactory sessionFactory;

    //初始化
    private Session session;
    private Transaction transaction;
    private void init(){
        session = sessionFactory.openSession();
        transaction = session.beginTransaction();
    }

    //銷燬
    private void destroy(){
        transaction.commit();
        session.close();
        sessionFactory.close();
    }


    @Override
    public void save(User user) {
        try{
            init();
            session.save(user);
            destroy();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public void delete(Integer id) {

    }

    @Override
    public void update(User user,Integer id) {
        try {
            init();
            user.setId(id);
            session.update(user);
            destroy();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public User findById(Integer id) {
        User user = new User();
        try{
            init();
            user = session.get(User.class,1);

            destroy();
        }catch (Exception e){
            e.printStackTrace();
        }
        return user;
        //Load方式
        /*
        User user = new User();
        try{
            init();
            user = session.load(User.class,1);
            destroy();
        }catch (Exception e){
            e.printStackTrace();
        }
        return user;
        */
    }

    @Override
    public List<User> getAll() {
        List<User> users=new ArrayList<>();
        try{
            init();
            users = session.createQuery("from User").list();
            destroy();
        }catch (Exception e){
            e.printStackTrace();
        }
        return users;
    }

    public SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }
}

UserDaoTest.java

package cn.edu.scnu.xmlcurd.dao.impl;

import cn.edu.scnu.xmlcurd.dao.UserDao;
import cn.edu.scnu.xmlcurd.entity.User;
import org.hibernate.cfg.Configuration;
import org.junit.Before;
import org.junit.Test;

import java.util.Date;
import java.util.List;

import static org.junit.Assert.*;

public class UserDaoImplTest {

    private UserDaoImpl userDao;

    @Before
    public void before(){
        userDao = new UserDaoImpl();
        userDao.setSessionFactory(new Configuration().configure().buildSessionFactory());
        System.out.println(userDao.getSessionFactory());
    }

    @Test
    public void save() {
        User user = new User();
        user.setUsername("小李");
        user.setPassword("12345");
        user.setRegisterDate(new Date());
        userDao.save(user);
    }

    @Test
    public void delete() {
        userDao.delete(1);
    }

    @Test
    public void update() {
        User user = new User();
        user.setUsername("喬峯");
        user.setPassword("12345");
        user.setRegisterDate(new Date());
        userDao.update(user,1);

    }

    @Test
    public void findById() {
        User user = userDao.findById(1);
        System.out.println(user.toString());
    }

    @Test
    public void getAll() {
        List<User> users = userDao.getAll();
        for(User user :users){
            System.out.println(user.toString());
        }
    }
}