Hibernate实战——条件查询

一 配置

<?xml version="1.0" encoding="GBK"?>
<!-- 指定Hibernate配置文件的DTD信息 -->
<!DOCTYPE hibernate-configuration PUBLIC
     "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
     "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<!-- hibernate-configuration是配置文件的根元素 -->
<hibernate-configuration>
     <session-factory>
           <!-- 指定连接数据库所用的驱动 -->
           <property  name="connection.driver_class">com.mysql.jdbc.Driver</property>
           <!-- 指定连接数据库的url，其中hibernate是本应用连接的数据库名 -->
           <property  name="connection.url">jdbc:mysql://localhost/hibernate</property>
           <!-- 指定连接数据库的用户名 -->
           <property name="connection.username">root</property>
           <!-- 指定连接数据库的密码 -->
           <property name="connection.password">32147</property>
           <!-- 指定连接池里最大连接数 -->
           <property  name="hibernate.c3p0.max_size">200</property>
           <!-- 指定连接池里最小连接数 -->
           <property name="hibernate.c3p0.min_size">2</property>
           <!-- 指定连接池里连接的超时时长 -->
           <property  name="hibernate.c3p0.timeout">5000</property>
           <!-- 指定连接池里最大缓存多少个Statement对象 -->
           <property  name="hibernate.c3p0.max_statements">100</property>
           <property  name="hibernate.c3p0.idle_test_period">3000</property>
           <property  name="hibernate.c3p0.acquire_increment">2</property>
           <property  name="hibernate.c3p0.validate">true</property>
           <!-- 指定数据库方言 -->
           <property  name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
           <!-- 根据需要自动创建数据库 -->
           <property name="hbm2ddl.auto">update</property>
           <!-- 显示Hibernate持久化操作所生成的SQL -->
           <property name="show_sql">true</property>
           <!-- 将SQL脚本进行格式化后再输出 -->
           <property name="hibernate.format_sql">true</property>
           <!-- 罗列所有持久化类的类名 -->
           <mapping class="org.crazyit.app.domain.Enrolment"/>
           <mapping class="org.crazyit.app.domain.Student"/>
           <mapping class="org.crazyit.app.domain.Course"/>
     </session-factory>
</hibernate-configuration>

二 PO

Student

package org.crazyit.app.domain;
import java.util.*;
import javax.persistence.*;
@Entity
@Table(name="student_inf")
public class Student
{
    // 代表学生学号的成员变量，将作为标识属性
    @Id @Column(name="student_id")
    private Integer studentNumber;
    // 代表学生姓名的成员变量
    private String name;
    // 该学生的所有选课记录对应的关联实体
    @OneToMany(targetEntity=Enrolment.class
        , mappedBy="student" , cascade=CascadeType.REMOVE)
    private Set<Enrolment> enrolments
        = new HashSet<>();
    // 无参数的构造器
    public Student()
    {
    }
    // 初始化全部成员变量的构造器
    public Student(Integer studentNumber , String name)
    {
        this.studentNumber = studentNumber;
        this.name = name;
    }
    // studentNumber的setter和getter方法
    public void setStudentNumber(Integer studentNumber)
    {
        this.studentNumber = studentNumber;
    }
    public Integer getStudentNumber()
    {
        return this.studentNumber;
    }
    // name的setter和getter方法
    public void setName(String name)
    {
        this.name = name;
    }
    public String getName()
    {
        return this.name;
    }
    // enrolments的setter和getter方法
    public void setEnrolments(Set<Enrolment> enrolments)
    {
        this.enrolments = enrolments;
    }
    public Set<Enrolment> getEnrolments()
    {
        return this.enrolments;
    }
}

Enrolment

package org.crazyit.app.domain;
import javax.persistence.*;
@Entity
@Table(name = "enrolment_inf")
public class Enrolment
{
     // 定义标识属性
     @Id
     @Column(name = "enrolment_id")
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Integer enrolmentId;
     // 定义选课记录所属的学年
     private int year;
     // 定义选课记录所属的学期
     private int semester;
     // 定义选课记录关联的学生实体
     @ManyToOne(targetEntity = Student.class)
     @JoinColumn(name = "student_id")
     private Student student;
     // 定义选课记录关联的课程实体
     @ManyToOne(targetEntity = Course.class)
     @JoinColumn(name = "course_code")
     private Course course;
     // enrolmentId的setter和getter方法
     public void setEnrolmentId(Integer enrolmentId) {
           this.enrolmentId = enrolmentId;
     }
     public Integer getEnrolmentId() {
           return this.enrolmentId;
     }
     // year的setter和getter方法
     public void setYear(int year) {
           this.year = year;
     }
     public int getYear() {
           return this.year;
     }
     // semester的setter和getter方法
     public void setSemester(int semester) {
           this.semester = semester;
     }
     public int getSemester() {
           return this.semester;
     }
     // student的setter和getter方法
     public void setStudent(Student student) {
           this.student = student;
     }
     public Student getStudent() {
           return this.student;
     }
     // course的setter和getter方法
     public void setCourse(Course course) {
           this.course = course;
     }
     public Course getCourse() {
           return this.course;
     }
}

Course

package org.crazyit.app.domain;
import javax.persistence.*;
@Entity
@Table(name="course_inf")
public class Course
{
     // 代表课程编号的成员变量，将作为标识属性
     @Id @Column(name="course_code")
     private String courseCode;
     // 代表课程名成员变量
     private String name;
     // 无参数的构造器
     public Course()
     {
     }
     // 初始化全部成员变量的构造器
     public Course(String courseCode , String name)
     {
           this.courseCode = courseCode;
           this.name = name;
     }
     // courseCode的setter和getter方法
     public void setCourseCode(String courseCode)
     {
           this.courseCode = courseCode;
     }
     public String getCourseCode()
     {
           return this.courseCode;
     }
     // name的setter和getter方法
     public void setName(String name)
     {
           this.name = name;
     }
     public String getName()
     {
           return this.name;
     }
}

三 测试

1 工具类

package lee;
import org.hibernate.*;
import org.hibernate.cfg.*;
import org.hibernate.service.*;
import org.hibernate.boot.registry.*;
public class HibernateUtil
{
    public static final SessionFactory sessionFactory;
    static
    {
        try
        {
            // 使用默认的hibernate.cfg.xml配置文件创建Configuration实例
            Configuration cfg = new Configuration()
                .configure();
            // 以Configuration实例来创建SessionFactory实例
            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                .applySettings(cfg.getProperties()).build();
            sessionFactory = cfg.buildSessionFactory(serviceRegistry);
        }
        catch (Throwable ex)
        {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }
    // ThreadLocal可以隔离多个线程的数据共享，因此不再需要对线程同步
    public static final ThreadLocal<Session> session
        = new ThreadLocal<Session>();
    public static Session currentSession()
        throws HibernateException
    {
        Session s = session.get();
        // 如果该线程还没有Session,则创建一个新的Session
        if (s == null)
        {
            s = sessionFactory.openSession();
            // 将获得的Session变量存储在ThreadLocal变量session里
            session.set(s);
        }
        return s;
    }
    public static void closeSession()
        throws HibernateException
    {
        Session s = session.get();
        if (s != null)
            s.close();
        session.set(null);
    }
}

2 测试类

package lee;
import org.hibernate.*;
import org.hibernate.criterion.Criterion;
import org.hibernate.criterion.Restrictions;
import org.crazyit.app.domain.*;
import java.util.*;
public class CriteriaTest {
    public static void main(String[] args) {
        CriteriaTest criteriaTest = new CriteriaTest();
        criteriaTest.query();
        criteriaTest.queryWithJoin();
        criteriaTest.queryWithFecth();
        HibernateUtil.sessionFactory.close();
    }
    private void query() {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        // 使用createCriteria开始条件查询
        List list = session.createCriteria(Student.class)
                // 根据Student的属性进行过滤数据
                .add(Restrictions.gt("name", "a")).list();
        System.out.println("=====简单条件查询获取所有学生记录=====");
        for (Object obj : list) {
            Student s = (Student) obj;
            System.out.println(s.getName());
            Set<Enrolment> enrolments = s.getEnrolments();
            System.out.println("=====获取-" + s.getName() + "-的选课记录=====");
            for (Enrolment e : enrolments) {
                System.out.println(e.getCourse().getName());
            }
        }
        tx.commit();
        HibernateUtil.closeSession();
    }
    // 示范根据关联实体的属性过滤数据
    private void queryWithJoin() {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        // 使用createCriteria开始条件查询
        List list = session.createCriteria(Student.class)
                // 此处增加限制条件必须是Student实体存在的属性
                .add(Restrictions.gt("studentNumber", 20050231))
                // 如果要增加对Student的关联类的属性的限制
                // 则必须重新createCriteria()
                // 如果此关联属性是集合，则只要集合里任意一个对象的属性满足下面条件即可
//            .createCriteria("enrolments")
//            .add( Restrictions.gt("semester" , 2))
                .createAlias("enrolments", "en").add(Restrictions.gt("en.semester", 2)).list();
        System.out.println("=====关联条件查询获取所有学生记录=====");
        for (Object obj : list) {
            Student s = (Student) obj;
            System.out.println(s.getName());
            Set<Enrolment> enrolments = s.getEnrolments();
            System.out.println("=====获取-" + s.getName() + "-的选课记录=====");
            for (Enrolment e : enrolments) {
                System.out.println(e.getCourse().getName());
            }
        }
        tx.commit();
        HibernateUtil.closeSession();
    }
    // 示范FetchMode的用法
    private void queryWithFecth() {
        // 打开Session和事务
        Session session = HibernateUtil.currentSession();
        Transaction tx = session.beginTransaction();
        // 使用createCriteria开始条件查询
        List list = session.createCriteria(Student.class)
                // 此处增加限制条件必须是Student实体存在的属性
                .add(Restrictions.gt("studentNumber", 20050231)).setFetchMode("enrolments", FetchMode.JOIN).list();
        tx.commit();
        HibernateUtil.closeSession(); // ①
        System.out.println("=====启用预初始化的条件查询获取所有学生记录=====");
        for (Object obj : list) {
            Student s = (Student) obj;
            System.out.println(s.getName());
            // Session关闭后访问Student的关联实体
            Set<Enrolment> enrolments = s.getEnrolments(); // ②
            System.out.println(enrolments);
        }
    }
}

四 数据脚本

drop database if exists hibernate;
create database hibernate;
use hibernate;
CREATE TABLE course_inf (
  course_code varchar(255) NOT NULL,
  name varchar(255) default NULL,
  PRIMARY KEY  (course_code)
);
INSERT INTO course_inf VALUES
('001','疯狂Java讲义'),
('002','轻量级Java EE企业应用实战'),
('003','疯狂Android讲义');
CREATE TABLE student_inf (
  student_id int NOT NULL,
  name varchar(255) NOT NULL,
  PRIMARY KEY  (student_id)
);
INSERT INTO student_inf VALUES
(20050231,'孙悟空'),
(20050232,'猪八戒'),
(20050233,'牛魔王');
CREATE TABLE enrolment_inf (
  enrolment_id int(11) NOT NULL auto_increment,
  semester int(11) NOT NULL,
  year int(11) NOT NULL,
  student_id int default NULL,
  course_code varchar(255) default NULL,
  PRIMARY KEY  (enrolment_id),
  KEY FKEB4882C47EDE09EE (course_code),
  KEY FKEB4882C4109881D8 (student_id),
  FOREIGN KEY (student_id) REFERENCES student_inf (student_id),
  FOREIGN KEY (course_code) REFERENCES course_inf (course_code)
);
INSERT INTO enrolment_inf VALUES
(1,3,2005,20050232,'001'),
(2,2,2005,20050232,'003'),
(3,2,2005,20050233,'002'),
(4,3,2005,20050233,'003'),
(5,1,2005,20050231,'002');

五 测试

Hibernate:
    select
        this_.student_id as student_1_2_0_,
        this_.name as name2_2_0_
    from
        student_inf this_
    where
        this_.name>?
=====1 简单条件查询获取所有学生记录=====
孙悟空
=====获取-孙悟空-的选课记录=====
Hibernate:
    select
        enrolments0_.student_id as student_5_2_0_,
        enrolments0_.enrolment_id as enrolmen1_1_0_,
        enrolments0_.enrolment_id as enrolmen1_1_1_,
        enrolments0_.course_code as course_c4_1_1_,
        enrolments0_.semester as semester2_1_1_,
        enrolments0_.student_id as student_5_1_1_,
        enrolments0_.year as year3_1_1_,
        course1_.course_code as course_c1_0_2_,
        course1_.name as name2_0_2_
    from
        enrolment_inf enrolments0_
    left outer join
        course_inf course1_
            on enrolments0_.course_code=course1_.course_code
    where
        enrolments0_.student_id=?
轻量级Java EE企业应用实战
猪八戒
=====获取-猪八戒-的选课记录=====
Hibernate:
    select
        enrolments0_.student_id as student_5_2_0_,
        enrolments0_.enrolment_id as enrolmen1_1_0_,
        enrolments0_.enrolment_id as enrolmen1_1_1_,
        enrolments0_.course_code as course_c4_1_1_,
        enrolments0_.semester as semester2_1_1_,
        enrolments0_.student_id as student_5_1_1_,
        enrolments0_.year as year3_1_1_,
        course1_.course_code as course_c1_0_2_,
        course1_.name as name2_0_2_
    from
        enrolment_inf enrolments0_
    left outer join
        course_inf course1_
            on enrolments0_.course_code=course1_.course_code
    where
        enrolments0_.student_id=?
疯狂Java讲义
疯狂Android讲义
牛魔王
=====获取-牛魔王-的选课记录=====
Hibernate:
    select
        enrolments0_.student_id as student_5_2_0_,
        enrolments0_.enrolment_id as enrolmen1_1_0_,
        enrolments0_.enrolment_id as enrolmen1_1_1_,
        enrolments0_.course_code as course_c4_1_1_,
        enrolments0_.semester as semester2_1_1_,
        enrolments0_.student_id as student_5_1_1_,
        enrolments0_.year as year3_1_1_,
        course1_.course_code as course_c1_0_2_,
        course1_.name as name2_0_2_
    from
        enrolment_inf enrolments0_
    left outer join
        course_inf course1_
            on enrolments0_.course_code=course1_.course_code
    where
        enrolments0_.student_id=?
轻量级Java EE企业应用实战
疯狂Android讲义
Hibernate:
    select
        this_.student_id as student_1_2_3_,
        this_.name as name2_2_3_,
        en1_.enrolment_id as enrolmen1_1_0_,
        en1_.course_code as course_c4_1_0_,
        en1_.semester as semester2_1_0_,
        en1_.student_id as student_5_1_0_,
        en1_.year as year3_1_0_,
        course4_.course_code as course_c1_0_1_,
        course4_.name as name2_0_1_,
        student5_.student_id as student_1_2_2_,
        student5_.name as name2_2_2_
    from
        student_inf this_
    inner join
        enrolment_inf en1_
            on this_.student_id=en1_.student_id
    left outer join
        course_inf course4_
            on en1_.course_code=course4_.course_code
    left outer join
        student_inf student5_
            on en1_.student_id=student5_.student_id
    where
        this_.student_id>?
        and en1_.semester>?
=====2 关联条件查询获取所有学生记录=====
猪八戒
=====获取-猪八戒-的选课记录=====
Hibernate:
    select
        enrolments0_.student_id as student_5_2_0_,
        enrolments0_.enrolment_id as enrolmen1_1_0_,
        enrolments0_.enrolment_id as enrolmen1_1_1_,
        enrolments0_.course_code as course_c4_1_1_,
        enrolments0_.semester as semester2_1_1_,
        enrolments0_.student_id as student_5_1_1_,
        enrolments0_.year as year3_1_1_,
        course1_.course_code as course_c1_0_2_,
        course1_.name as name2_0_2_
    from
        enrolment_inf enrolments0_
    left outer join
        course_inf course1_
            on enrolments0_.course_code=course1_.course_code
    where
        enrolments0_.student_id=?
疯狂Android讲义
疯狂Java讲义
牛魔王
=====获取-牛魔王-的选课记录=====
Hibernate:
    select
        enrolments0_.student_id as student_5_2_0_,
        enrolments0_.enrolment_id as enrolmen1_1_0_,
        enrolments0_.enrolment_id as enrolmen1_1_1_,
        enrolments0_.course_code as course_c4_1_1_,
        enrolments0_.semester as semester2_1_1_,
        enrolments0_.student_id as student_5_1_1_,
        enrolments0_.year as year3_1_1_,
        course1_.course_code as course_c1_0_2_,
        course1_.name as name2_0_2_
    from
        enrolment_inf enrolments0_
    left outer join
        course_inf course1_
            on enrolments0_.course_code=course1_.course_code
    where
        enrolments0_.student_id=?
轻量级Java EE企业应用实战
疯狂Android讲义
Hibernate:
    select
        this_.student_id as student_1_2_2_,
        this_.name as name2_2_2_,
        enrolments2_.student_id as student_5_2_4_,
        enrolments2_.enrolment_id as enrolmen1_1_4_,
        enrolments2_.enrolment_id as enrolmen1_1_0_,
        enrolments2_.course_code as course_c4_1_0_,
        enrolments2_.semester as semester2_1_0_,
        enrolments2_.student_id as student_5_1_0_,
        enrolments2_.year as year3_1_0_,
        course3_.course_code as course_c1_0_1_,
        course3_.name as name2_0_1_
    from
        student_inf this_
    left outer join
        enrolment_inf enrolments2_
            on this_.student_id=enrolments2_.student_id
    left outer join
        course_inf course3_
            on enrolments2_.course_code=course3_.course_code
    where
        this_.student_id>?
=====3 启用预初始化的条件查询获取所有学生记录=====
猪八戒
[org.crazyit.app.domain.Enrolment@736caf7a,  org.crazyit.app.domain.Enrolment@3da05287]
猪八戒
[org.crazyit.app.domain.Enrolment@736caf7a,  org.crazyit.app.domain.Enrolment@3da05287]
牛魔王
[org.crazyit.app.domain.Enrolment@497486b3,  org.crazyit.app.domain.Enrolment@6127a7e]
牛魔王
[org.crazyit.app.domain.Enrolment@497486b3,  org.crazyit.app.domain.Enrolment@6127a7e]