Hibernate检索（下）

1.表结构

2.HQL连接查询

Hibernate支持的连接有：

inner join

left outer join

right outer join

inner join只能得到满足连接条件的记录，左右表交换位置，结果不变。

left join 左表中的数据必须出现在结果集中，哪怕不满足连接条件。

right join 右表中的数据必须出现在结果集中，哪怕不满足连接条件。

3.实体类

package cn.yunhe.entity;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "users")
public class Users {
    private int id;
    private String loginId;
    private String loginPwd;
    private String name;
    private int age;
    private String phone;
    private Set<Orders> orders= new HashSet<Orders>();

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

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

    @Column(name = "loginId")
    public String getLoginId() {
        return loginId;
    }

    public void setLoginId(String loginId) {
        this.loginId = loginId;
    }

    @Column(name = "loginPwd")
    public String getLoginPwd() {
        return loginPwd;
    }

    public void setLoginPwd(String loginPwd) {
        this.loginPwd = loginPwd;
    }

    @Column(name = "name")
    public String getName() {
        return name;
    }

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

    @Column(name = "age")
    public int getAge() {
        return age;
    }

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

    @Column(name = "phone")
    public String getPhone() {
        return phone;
    }

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

    @OneToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY,mappedBy = "users")//双向时不要@JoinColumn
    //@JoinColumn(name = "userid")
    public Set<Orders> getOrders() {
        return orders;
    }

    public void setOrders(Set<Orders> orders) {
        this.orders = orders;
    }
}

package cn.yunhe.entity;

import javax.persistence.*;
import java.util.Date;

/**
 * Created by Administrator on 2017/7/11.
 */
@Entity
@Table(name = "orders")
public class Orders {
    private int id;
    private Date orderDate;
    private double totalPrice;
    private Users users;

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

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

    @Column(name = "orderDate")
    public Date getOrderDate() {
        return orderDate;
    }

    public void setOrderDate(Date orderDate) {
        this.orderDate = orderDate;
    }

    @Column(name = "totalPrice")
    public double getTotalPrice() {
        return totalPrice;
    }

    public void setTotalPrice(double totalPrice) {
        this.totalPrice = totalPrice;
    }

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "userid")
    public Users getUsers() {
        return users;
    }

    public void setUsers(Users users) {
        this.users = users;
    }
}

4.配置文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration
        PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!--正向工程（自动建表）-->
        <property name="hbm2ddl.auto">update</property>
        <!--数据库方言-->
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.username">root</property>
        <property name="connection.password">1234</property>
        <!--显示sql语句-->
        <property name="show_sql">true</property>

        <mapping class="cn.yunhe.entity.Users"/>
        <mapping class="cn.yunhe.entity.Orders"/>

    </session-factory>
</hibernate-configuration>

<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>cn.yunhe</groupId>
  <artifactId>hibernate5</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>hibernate5 Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.6</version>
    </dependency>

    <dependency>
      <groupId>org.apache.struts</groupId>
      <artifactId>struts2-core</artifactId>
      <version>2.3.31</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>

    <dependency>
      <groupId>org.apache.struts</groupId>
      <artifactId>struts2-dojo-plugin</artifactId>
      <version>2.3.16</version>
    </dependency>

    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-core</artifactId>
      <version>3.5.0-Final</version>
    </dependency>

    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-annotations</artifactId>
      <version>3.5.0-Final</version>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>1.5.8</version>
    </dependency>

    <dependency>
      <groupId>org.javassist</groupId>
      <artifactId>javassist</artifactId>
      <version>3.13.0-GA</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>hibernate5</finalName>
  </build>
</project>

5.测试类

package cn.yunhe.Demo;

import cn.yunhe.entity.Books;
import cn.yunhe.entity.Orders;
import cn.yunhe.entity.Publishers;
import cn.yunhe.entity.Users;
import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.util.List;

/**
 * Created by Administrator on 2017/7/11.
 */
public class Demo {
    Session session=null;
    Transaction tr=null;

    @Before
    public void init(){
        Configuration config =new AnnotationConfiguration().configure();
        session= config.buildSessionFactory().openSession();
        tr=session.beginTransaction();
    }

    @Test //Hibernate内链接    查询订单中的用户的信息
    public void test1(){
        String hql="select o.users from Orders o where o.id=1";
        Query query=session.createQuery(hql);
         List<Users> list= query.list();
        session.close();//关闭也可以查出来
        Users user=list.get(0);
        System.out.println(user.getName());
    }

    @Test //Hibernate内链接  使用交叉连接查询
    public void test2(){
        String hql="select u from Users u,Orders o where u=o.users and o.id=3";
        List<Users> list= session.createQuery(hql).list();
        for (Users users:list){
            System.out.println(users.getName());
        }
    }

    @Test//Hibernate内链接  查询所有购买过书籍的用户，采用子查询
    public void test3(){
        String hql="select u from Users u where u in(select o.users from Orders o)";//子查询
        //String hql="select distinct u from Users u inner join u.orders";//内连接
        List<Users> list =session.createQuery(hql).list();
        for (Users users:list){
            System.out.println(users.getName());
        }
    }

    @Test//Hibernate内链接  抓取内链接
    public  void test4(){
       String hql="select distinct u from Users u inner join u.orders";
       List<Users> list= session.createQuery(hql).list();
       session.close();//关闭session
        for (Users users:list){
            System.out.println(users.getName()+"的订单：");
            for (Orders orders:users.getOrders()){
                System.out.println(orders.getId()+"	"+orders.getTotalPrice());
            }
        }
    }

    @Test//Hibernate外链接 left outer join(左外链接)
    //查询没有任何订单的用户
    //left join中也可以使用fetch，即:left join fetch,表示是否填充左边（Users）中的集合属性
    public void test5(){
        String hql="select u from Users u left join u.orders o where o is null";
        List<Users> list= session.createQuery(hql).list();
        for (Users users:list){
            System.out.println(users.getName());
        }
    }

    @Test//本地查询 原生SQL语句查询   session.createSQLQuery()方法
    public void test6(){
        String sql="select * from users";
        Query query=session.createSQLQuery(sql);
        List<Object[]> list= query.list();
        for (Object[] objects :list){
            System.out.println(objects[1]);
        }
    }

    @Test//本地查询 原生sql语句查询  使用占位符
    /*说明：查询指定了 SQL查询语句，带一个占位符，可以让Hibernate使用字段的别名
    . 查询返回的实体，和它的SQL表的别名. addEntity()方法将SQL表的别名和实体类联
     系起来。
    * */
    public void test7(){
        String sql="select {u.*},{o.*} from users u,orders o where u.id=o.userid";
        Query query=session.createSQLQuery(sql).addEntity("u",Users.class).addEntity("o",Orders.class);
        List<Object[]> list= query.list();
        for (Object[] objects:list){
            Users users= (Users) objects[0];
            Orders orders= (Orders) objects[1];
            System.out.println("用户名："+users.getName()+",订单价格"+orders.getTotalPrice());
        }
    }

    @Test //Criteria查询   使用Criteria查询所有的用户
    public void test8(){
        Criteria criteria=session.createCriteria(Users.class);
        List<Users> list= criteria.list();
        for (Users users:list){
            System.out.println(users.getName());
        }
    }

    @Test//Criteria查询 条件查询
    //使用Restrictions中的静态方法来构造查询条件，然后“add”到Criteria中
    //查询出年龄大于400的用户
    public void test9(){
        Criteria criteria=session.createCriteria(Users.class);
        List<Users> list= criteria.add(Restrictions.gt("age",400)).list();
        for (Users users:list){
            System.out.println(users.getName()+",age:"+users.getAge());
        }

    }

    @Test//Criteria查询  排序   根据年龄进行降序排列
    public void test10(){
        Criteria criteria=session.createCriteria(Users.class);
        List<Users> list= criteria.addOrder(Order.desc("age")).list();
        for (Users users:list){
            System.out.println(users.getName()+",age:"+users.getAge());
        }
    }

    @Test//Criteria查询  分页
    // setFirstResult方法设置开始位置
    //  setMaxResult方法设置页大小
    public void  test11(){
        Criteria criteria=session.createCriteria(Users.class);
        List<Users> list= criteria.setFirstResult(2).setMaxResults(3).list();
        for (Users users:list){
            System.out.println(users.getName()+",age:"+users.getAge());
        }
    }

    @Test// Criteria查询 使用聚合函数  使用Criteria 的setProjection 方法设置统计列  max min avg sum 等用法相同
    public void test12(){
        Criteria criteria=session.createCriteria(Users.class);
        criteria.setProjection(Projections.avg("age"));
        Double age= (Double) criteria.uniqueResult();
        System.out.println("员工的平均年龄是："+age);
    }

    @Test//Criteria查询 连接查询
    //使用createCriteria() 方法非常容易地在互相关联的实体间进行连接查询
    //查询孙权的订单信息，要求订单总价在300以上。
    public void test13(){
        Criteria c_orders=session.createCriteria(Orders.class);
        Criteria c_users=c_orders.createCriteria("users");//两表关联，这步最重要
        c_orders.add(Restrictions.gt("totalPrice",300d));//double类型后面要加d  不然会报无法将integer转换为double
        c_users.add(Restrictions.eq("id",1));
        List<Orders> list= c_orders.list();
        for (Orders orders:list){
            System.out.println("客户名称:"+orders.getUsers().getName()+"
订单总价："+orders.getTotalPrice());
        }
    }

    @After
    public void down(){
        session.close();
    }

}

6.HQL优化