Hibernate四

1 Hibernate的查询方式

1.1 Hibernate的查询方式

• 在Hibernate中有提供了很多种的查询方式。
Hibernate一共提供了5种查询方式：
• OID查询。
• 对象导航查询。
• HQL查询。
• QBC查询。
• SQL查询。　　

1.2 OID查询

• OID检索：HIbernate根据对象的OID（主键）查询。例如：使用get或load方法查询对象。

1.3 对象导航查询

• Hibernate根据一个已经查询到的对象，获取其关联对象的一种查询方式。例如：先查询到了联系人的信息，然后通过联系人对象获取对应的客户信息。

1.4 HQL查询

• HQL：Hibernate查询语言，是一种面向对象的方式的查询语言，语法类似SQL。通过session.createQuery()，用于接收一个HQL进行查询的方式。

1.4.1 搭建环境并进行数据初始化

• Customer.java

package com.xuweiwei.hibernate;

import java.util.HashSet;
import java.util.Set;

/**
 * 客户
 *
 * @author 许威威
 */
public class Customer {
    /**
     * 客户编号(主键)
     */
    private Long id;
    /**
     * 客户名称(公司名称)
     */
    private String name;
    /**
     * 客户信息来源
     */
    private String source;
    /**
     * 客户所属行业
     */
    private String industry;
    /**
     * 客户级别
     */
    private String level;
    /**
     * 固定电话
     */
    private String phone;
    /**
     * 移动电话
     */
    private String mobile;
    //一个客户有多个联系人
    private Set<LinkMan> linkMans = new HashSet<>();

    public Long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getSource() {
        return source;
    }

    public void setSource(String source) {
        this.source = source;
    }

    public String getIndustry() {
        return industry;
    }

    public void setIndustry(String industry) {
        this.industry = industry;
    }

    public String getLevel() {
        return level;
    }

    public void setLevel(String level) {
        this.level = level;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getMobile() {
        return mobile;
    }

    public void setMobile(String mobile) {
        this.mobile = mobile;
    }

    public Set<LinkMan> getLinkMans() {
        return linkMans;
    }

    public void setLinkMans(Set<LinkMan> linkMans) {
        this.linkMans = linkMans;
    }
}

View Code

• LinkMan.java

package com.xuweiwei.hibernate;


/**
 * 联系人
 *
 * @author 许威威
 */
public class LinkMan {
    /**
     * 主键
     */
    private Long id;
    /**
     * 联系人姓名
     */
    private String name;
    /**
     * 联系人性别
     */
    private Character gender;
    /**
     * 联系人办公电话
     */
    private String phone;
    /**
     * 联系人手机
     */
    private String mobile;
    /**
     * 联系人邮箱
     */
    private String email;
    /**
     * 联系人QQ
     */
    private String qq;
    /**
     * 联系人职位
     */
    private String position;
    /**
     * 联系人备注
     */
    private String memo;
    //一个联系人属于一个客户
    private Customer customer;

    public Long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public Character getGender() {
        return gender;
    }

    public void setGender(Character gender) {
        this.gender = gender;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getMobile() {
        return mobile;
    }

    public void setMobile(String mobile) {
        this.mobile = mobile;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getQq() {
        return qq;
    }

    public void setQq(String qq) {
        this.qq = qq;
    }

    public String getPosition() {
        return position;
    }

    public void setPosition(String position) {
        this.position = position;
    }

    public String getMemo() {
        return memo;
    }

    public void setMemo(String memo) {
        this.memo = memo;
    }

    public Customer getCustomer() {
        return customer;
    }

    public void setCustomer(Customer customer) {
        this.customer = customer;
    }
}

View Code

• Customer.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <!-- 建立类与表的映射 -->
    <class name="com.xuweiwei.hibernate.Customer" table="customer">
        <!-- 建立类中的属性与表中的主键对应 -->
        <id name="id" column="id">
            <generator class="native"></generator>
        </id>
        <!-- 建立类中的普通的属性和表的字段的对应 -->
        <property name="name" column="name"/>
        <property name="source" column="source"/>
        <property name="industry" column="industry"/>
        <property name="level" column="level"/>
        <property name="phone" column="phone"/>
        <property name="mobile" column="mobile"/>

        <set name="linkMans">
            <key column="customer_id"></key>
            <one-to-many class="com.xuweiwei.hibernate.LinkMan"/>
        </set>


    </class>
</hibernate-mapping>

View Code

• LinkMan.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <!-- 建立类与表的映射 -->
    <class name="com.xuweiwei.hibernate.LinkMan" table="linkMan">
        <!-- 建立类中的属性与表中的主键对应 -->
        <id name="id" column="id">
            <generator class="native"></generator>
        </id>
        <!-- 建立类中的普通的属性和表的字段的对应 -->
        <property name="name" column="name"/>
        <property name="gender" column="gender"/>
        <property name="phone" column="phone"/>
        <property name="mobile" column="mobile"/>
        <property name="email" column="email"/>
        <property name="qq" column="qq"/>
        <property name="position" column="position"/>
        <property name="memo" column="memo"/>

        <many-to-one name="customer" class="com.xuweiwei.hibernate.Customer" column="customer_id"/>


    </class>
</hibernate-mapping>

View Code

• 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>
        <!-- 连接数据库的基本参数 -->
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql:///hibernate</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">123456</property>
        <!-- 配置Hibernate的方言 -->
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <!-- 可选配置================ -->
        <!-- 打印SQL -->
        <property name="hibernate.show_sql">true</property>
        <!-- 格式化SQL -->
        <property name="hibernate.format_sql">true</property>
        <!-- 自动创建表 -->
        <property name="hibernate.hbm2ddl.auto">update</property>

        <!-- 加载映射文件 -->
        <mapping resource="com/xuweiwei/hibernate/Customer.hbm.xml"/>
        <mapping resource="com/xuweiwei/hibernate/LinkMan.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

View Code

• log4j.properties

### direct log messages to stdout ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.err
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n

### direct messages to file mylog.log ###
log4j.appender.file=org.apache.log4j.FileAppender
log4j.appender.file.File=c\:mylog.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n

### set log levels - for more verbose logging change 'info' to 'debug' ###
# error warn info debug trace
log4j.rootLogger= info, stdout

View Code

• 初始化数据

    //初始化数据
    @Test
    public void test() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();
        Customer customer1 = new Customer();
        customer1.setName("张无忌");
        Customer customer2 = new Customer();
        customer2.setName("张三丰");
        for (int i = 0; i < 10; i++) {
            LinkMan linkMan = new LinkMan();
            linkMan.setName("赵敏" + (i+1));
            customer1.getLinkMans().add(linkMan);
            linkMan.setCustomer(customer1);

            session.save(linkMan);
        }
        for (int i = 0; i < 10; i++) {
            LinkMan linkMan = new LinkMan();
            linkMan.setName("郭襄" + (i+1));
            customer2.getLinkMans().add(linkMan);
            linkMan.setCustomer(customer2);

            session.save(linkMan);
        }
        session.save(customer1);
        session.save(customer2);

        transaction.commit();
        session.close();
    }

1.4.2 HQL的简单查询

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        Query query = session.createQuery(" from Customer ");
        List<Customer> list = query.list();
        for (Customer customer : list) {
            System.out.println(customer);
        }

        transaction.commit();
        session.close();
    }

• 示例：别名查询

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        Query query = session.createQuery(" from Customer c");
        List<Customer> list = query.list();
        for (Customer customer : list) {
            System.out.println(customer);
        }

        transaction.commit();
        session.close();
    }

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        Query query = session.createQuery("select c from Customer c");
        List<Customer> list = query.list();
        for (Customer customer : list) {
            System.out.println(customer);
        }

        transaction.commit();
        session.close();
    }

1.4.3 HQL的排序查询

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        //默认情况下，是升序
        Query query = session.createQuery("select c from Customer c order by id");
        List<Customer> list = query.list();

        System.out.println(list);

        transaction.commit();
        session.close();
    }

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        //默认情况下，是升序
        Query query = session.createQuery(" select c from Customer c order by c.id desc ");
        List<Customer> list = query.list();

        System.out.println(list);

        transaction.commit();
        session.close();
    }

1.4.4 条件查询

• 示例：按位置绑定：和JDBC一样，只不多Hibernate的位置是从0开始的。

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        Query query = session.createQuery(" select c from Customer c where c.id = ? ");
        query.setParameter(0,1L);
        List<Customer> list = query.list();

        System.out.println(list);

        transaction.commit();
        session.close();
    }

• 示例：按名称绑定

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        Query query = session.createQuery(" select c from Customer c where c.id = :id ");
        query.setParameter("id",1L);
        List<Customer> list = query.list();

        System.out.println(list);

        transaction.commit();
        session.close();
    }

1.4.5 HQL的投影查询

• 投影查询：查询某个对象的某个属性或部分属性。

• 示例：查询所有客户的名称

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        Query query = session.createQuery(" select c.name from Customer c  ");
        List<Object> list = query.list();

        System.out.println(list);

        transaction.commit();
        session.close();
    }

• 示例：查询所有客户的编号和名称

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        //SQL中支持*的写法，但是HQL不支持
        Query query = session.createQuery(" select c.id,c.name from Customer c  ");
        List<Object[]> list = query.list();

        for (Object[] objects : list) {
            System.out.println(Arrays.asList(objects));
        }

        transaction.commit();
        session.close();
    }

1.4.5 HQL的分组统计查询

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();
        //根据姓名分组
        Query query = session.createQuery("select l.name,count(l.id) from LinkMan l group by l.name ");
        List<Object[]> list = query.list();

        for (Object[] objects : list) {
            System.out.println(Arrays.asList(objects));
        }

        transaction.commit();
        session.close();
    }

1.4.6 HQL的分页查询

• 示例：分页显示联系人

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        Integer pageNo = 1;
        Integer pageSize = 5;

        Query query = session.createQuery(" from LinkMan  ");
        query.setFirstResult((pageNo - 1) * pageSize);
        query.setMaxResults(pageSize);

        List<LinkMan> list = query.list();
        System.out.println(list);

        transaction.commit();
        session.close();
    }

1.4.7 多表查询

• HQL支持的多表查询有：交叉连接、内连接（显示内连接，隐式内连接，迫切内连接）、外连接（左外连接、右外连接、迫切左外连接）。

• 所谓的迫切连接，就是在join后面添加一个关键字fetch。目的是通知Hibernate将另一个对象的数据封装到该对象中。

• 示例：内连接

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        Query query = session.createQuery(" from Customer c inner join c.linkMans ");
        List<Object[]> list = query.list();

        for (Object[] objects : list) {
            System.out.println(Arrays.toString(objects));
        }

        transaction.commit();
        session.close();
    }

• 示例：迫切内连接

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        Query query = session.createQuery(" select distinct c from Customer c inner join fetch c.linkMans ");
        List<Customer> list = query.list();

        list.forEach(System.out::println);

        transaction.commit();
        session.close();
    }

1.5 QBC查询

• QBC：条件查询。是一种更加面向对象化的查询方式。

1.5.1 简单查询

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        Criteria criteria = session.createCriteria(Customer.class);
        List<Customer> list = criteria.list();

        System.out.println(list);

        transaction.commit();
        session.close();
    }

1.5.2 排序查询

• 示例：根据id降序

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        Criteria criteria = session.createCriteria(Customer.class);
        List<Customer> list = criteria.addOrder(Order.desc("id")).list();

        System.out.println(list);

        transaction.commit();
        session.close();
    }

1.5.3 分页查询

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        Integer pageNo = 1;
        Integer pageSize = 5;

        Criteria criteria = session.createCriteria(LinkMan.class);
        criteria.setFirstResult((pageNo - 1) * pageSize);
        criteria.setMaxResults(pageSize);
        List<LinkMan> list = criteria.list();
        System.out.println(list);

        transaction.commit();
        session.close();
    }

1.5.4 条件查询

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        Criteria criteria = session.createCriteria(Customer.class);
        criteria.add(Restrictions.like("name","张", MatchMode.ANYWHERE));
        List<Customer> list = criteria.list();

        System.out.println(list);

        transaction.commit();
        session.close();
    }

1.5.5 统计查询

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        Criteria criteria = session.createCriteria(Customer.class);
        criteria.setProjection(Projections.rowCount());
        Object o = criteria.uniqueResult();
        System.out.println(o);

        transaction.commit();
        session.close();
    }

1.6 SQL查询

• 示例：

    @Test
    public void test1() {
        Session session = HibernateUtil.getSession();
        Transaction transaction = session.beginTransaction();

        SQLQuery sqlQuery = session.createSQLQuery(" select * from customer ").addEntity(Customer.class);
        List<Customer> list = sqlQuery.list();
        System.out.println(list);

        transaction.commit();
        session.close();
    }

2 Hibernate的抓取策略