Hibernate实战——条件查询

分手后的思念是犯贱 2021-07-25 01:06 492阅读 0赞

**一 配置**

<?xml version="1.0" encoding="GBK"?>
    
    <!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>
               
               <property  name="connection.driver_class">com.mysql.jdbc.Driver</property>
               
               <property  name="connection.url">jdbc:mysql://localhost/hibernate</property>
               
               <property name="connection.username">root</property>
               
               <property name="connection.password">32147</property>
               
               <property  name="hibernate.c3p0.max_size">200</property>
               
               <property name="hibernate.c3p0.min_size">2</property>
               
               <property  name="hibernate.c3p0.timeout">5000</property>
               
               <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>
               
               <property  name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
               
               <property name="hbm2ddl.auto">update</property>
               
               <property name="show_sql">true</property>
               
               <property name="hibernate.format_sql">true</property>
               
               <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');

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70][]

**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]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70]: /images/20210724/bd8af4f9c22249e2b57cfef4539c721f.png