hibernate单表，一对多，多对多注解详解

痛定思痛。 2022-06-08 00:09 235阅读 0赞

# 1.单表注解 #

**使用注解的方式映射实体bean与数据表的关系，实现单表的CRUD操作**

## 1.1 course.java ##

package com.demo.model;
    
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.Table;
    
    import org.hibernate.annotations.GenericGenerator;
    
    @Entity
    @Table(name = "course_anno")
    public class CourseAnno { 
        @Id
        @GenericGenerator(name = "generator",strategy="increment")
        @GeneratedValue(generator="generator")
        @Column(name="id")
        private int id;
    
        @Column(name="name")
        private String name;
    
        @Column(name="description")
        private String description;
    
        public CourseAnno() {
        }
    
        public CourseAnno(int id, String name, String description) {
            this.id = id;
            this.name = name;
            this.description = description;
        }
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getDescription() {
            return description;
        }
    
        public void setDescription(String description) {
            this.description = description;
        }
    
        public String toString() {
            return "CourseAnno [id=" + id + ", name=" + name + ", description="
                    + description + "]";
        }
    
    }

## 1.2 测试类TestCourseAnno.java ##

package com.demo.test2;
    
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.Transaction;
    import org.hibernate.cfg.AnnotationConfiguration;
    import org.hibernate.cfg.Configuration;
    import org.junit.After;
    import org.junit.Before;
    import org.junit.Test;
    import com.demo.model.CourseAnno;
    
    public class TestCourseAnno { 
        private SessionFactory sessionFactory;
        private Session session;
        private Transaction transaction;
    
        @Before
        public void init(){
            //创建配置对象，加载配置文件 hibernate.cfg.xml
            Configuration configuration = new AnnotationConfiguration().configure();
            //创建会话连接工厂
            sessionFactory = configuration.buildSessionFactory();
            //打开会话
            session = sessionFactory.openSession();
            //开启事务
            transaction = session.beginTransaction();
        }
    
        @After
        public void destory(){
            //提交事务
            transaction.commit();
            //关闭会话
            session.close();
            //关闭工厂会话连接
            sessionFactory.close();
    
        }
    
        /** * 新增课程信息 */
        @Test
        public void testSaveCourseAnno() {
            CourseAnno cou = new CourseAnno();
            cou.setName("c#");
            cou.setDescription("编程语言");
            session.save(cou);
    
            CourseAnno cou2 = new CourseAnno(2, "javascript", "脚本语言");
            session.save(cou2);
        }
    
        /** * 更新课程信息 */
        @Test
        public void testUpdateCou() {
            // 获取一个课程对象
            CourseAnno cou = (CourseAnno) session.get(CourseAnno.class, 1);
            cou.setName("java");
            session.save(cou);
        }
    
        /** * 删除课程信息 */
        @Test
        public void testDeletecou() {
            CourseAnno cou = (CourseAnno) session.get(CourseAnno.class, 2);
            session.delete(cou);
        }
    
        /** * 查询课程信息 */
        @Test
        public void testGetcou() {
            CourseAnno cou = (CourseAnno) session.get(CourseAnno.class, 1);
            System.out.println(cou);
    
        }
    
    }

# 2. 一对多注解 #

**假设一个学生能选择多门课程，而一门课程只能被一个学生选择，用注解的映射方式去操作数据库的CRUD操作**

## 2.1 课程类 CourseAnno3.java ##

package com.demo.model3;
    
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.ManyToOne;
    import javax.persistence.Table;
    import org.hibernate.annotations.GenericGenerator;
    
    @Entity
    @Table(name = "course_anno3")
    public class CourseAnno3 { 
    
        @Id
        @GenericGenerator(name = "generator",strategy="increment")
        @GeneratedValue(generator="generator")
        @Column(name="id")
        private Integer id;  //课程id
    
        @Column(name="name")
        private String name; // 课程名称
    
        @ManyToOne(targetEntity = StudentAnno3.class)
        @JoinColumn(name="sid")
        private StudentAnno3 stu;
    
        public CourseAnno3() {
        }
    
        public CourseAnno3(Integer id, String name) {
            this.id = id;
            this.name = name;
        }
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public StudentAnno3 getStu() {
            return stu;
        }
    
        public void setStu(StudentAnno3 stu) {
            this.stu = stu;
        }
    
        public String toString() {
            return "Course [id=" + id + ", name=" + name + "]";
        }
    
    }

## 2.2 学生类 StudentAnno3.java ##

package com.demo.model3;
    
    import java.util.Date;
    import java.util.HashSet;
    import java.util.Set;
    import javax.persistence.CascadeType;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.OneToMany;
    import javax.persistence.Table;
    import javax.persistence.Temporal;
    import javax.persistence.TemporalType;
    import org.hibernate.annotations.GenericGenerator;
    
    @Entity
    @Table(name = "student_anno3")
    public class StudentAnno3 { 
    
        @Id
        @GenericGenerator(name = "generator",strategy="increment")
        @GeneratedValue(generator="generator")
        @Column(name="sid")
        private Integer sid; // 学生id
    
        @Column(name="name")
        private String name; // 学生姓名
    
        @Column(name="gender")
        private String gender;
    
        @Column(name = "birthday")
        @Temporal(TemporalType.TIMESTAMP)
        private Date birthday;
    
        @OneToMany(targetEntity=CourseAnno3.class,cascade=CascadeType.ALL)
        @JoinColumn(name="sid")
        private Set<CourseAnno3> cous = new HashSet<CourseAnno3>();
    
        public StudentAnno3() {
    
        }
    
        public Integer getSid() {
            return sid;
        }
    
        public void setSid(Integer sid) {
            this.sid = sid;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getGender() {
            return gender;
        }
        public void setGender(String gender) {
            this.gender = gender;
        }
        public Date getBirthday() {
            return birthday;
        }
        public void setBirthday(Date birthday) {
            this.birthday = birthday;
        }
        public Set<CourseAnno3> getCous() {
            return cous;
        }
        public void setCous(Set<CourseAnno3> cous) {
            this.cous = cous;
        }
    
        public String toString() {
            return "Student [sid=" + sid + ", name=" + name + ", gender=" + gender
                    + ", birthday=" + birthday + "]";
        }
    
    }

## 2.3 测试类 TestStudentAnno3.java ##

package com.demo.test3;
    
    import java.util.Date;
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.Transaction;
    import org.hibernate.cfg.AnnotationConfiguration;
    import org.hibernate.cfg.Configuration;
    import org.junit.After;
    import org.junit.Before;
    import org.junit.Test;
    import com.demo.model3.CourseAnno3;
    import com.demo.model3.StudentAnno3;
    
    public class TestStudentAnno3 { 
    
        private SessionFactory sessionFactory;
        private Session session;
        private Transaction transaction;
    
        @Before
        public void init(){
            //创建配置对象，加载配置文件 hibernate.cfg.xml
            Configuration configuration = new AnnotationConfiguration().configure();
            //创建会话连接工厂
            sessionFactory = configuration.buildSessionFactory();
            //打开会话
            session = sessionFactory.openSession();
            //开启事务
            transaction = session.beginTransaction();
        }
    
        @After
        public void destory(){
            //提交事务
            transaction.commit();
            //关闭会话
            session.close();
            //关闭工厂会话连接
            sessionFactory.close();
    
        }
    
    
        /** * 新增学生信息 */
        @Test
        public void testSaveStudent() {
            StudentAnno3 stu = new StudentAnno3();
            stu.setName("张三丰");
            stu.setGender("男");
            stu.setBirthday(new Date());
    
            CourseAnno3 cou1 = new CourseAnno3();
            cou1.setName("java");
    
            CourseAnno3 cou2 = new CourseAnno3();
            cou2.setName("c");
    
            stu.getCous().add(cou1);
            stu.getCous().add(cou2);
    
            session.save(stu);
    
        }
    
        /** * 更新学生信息 */
        @Test
        public void testUpdateStu() {
            // 获取一个学生对象
            StudentAnno3 stu = (StudentAnno3) session.get(StudentAnno3.class, 1);
            stu.setName("张峰");
            session.save(stu);
        }
    
        /** * 删除学生信息 同时删除课程表相关信息 */
        @Test
        public void testDeleteStu() {
            StudentAnno3 stu = (StudentAnno3) session.get(StudentAnno3.class, 1);
            session.delete(stu);
        }
    
        /** * 查询学生信息 */
        @Test
        public void testGetStu() {
            StudentAnno3 stu = (StudentAnno3) session.get(StudentAnno3.class, 1);
            System.out.println(stu);
        }
    
    }

# 3.多对多注解 #

**考虑到实际情况，其实是一个学生可以选择多门课程，一门课程也可以被多个学生选择，所以这里的关系应该是多对多的关系，用注解的方式实现数据库的CRUD操作**

## 3.1 课程类 CourseAnno4.java ##

package com.demo.model4;
    
    import java.util.HashSet;
    import java.util.Set;
    import javax.persistence.CascadeType;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.JoinTable;
    import javax.persistence.ManyToMany;
    import javax.persistence.Table;
    import org.hibernate.annotations.GenericGenerator;
    
    @Entity
    @Table(name = "course_anno4")
    public class CourseAnno4 { 
    
        @Id
        @GenericGenerator(name = "generator",strategy="increment")
        @GeneratedValue(generator="generator")
        @Column(name="id")
        private Integer id;  //课程id
    
        @Column(name="name")
        private String name; // 课程名称
    
        @ManyToMany(cascade=CascadeType.ALL)
        @JoinTable(name="student_course4",joinColumns={
       @JoinColumn(name="id")},inverseJoinColumns={
       @JoinColumn(name="sid")})
        private Set<StudentAnno4> students=new HashSet<StudentAnno4>();
    
        public CourseAnno4() {
        }
    
        public CourseAnno4(Integer id, String name) {
            this.id = id;
            this.name = name;
        }
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Set<StudentAnno4> getStudents() {
            return students;
        }
    
        public void setStudents(Set<StudentAnno4> students) {
            this.students = students;
        }
    
        public String toString() {
            return "Course [id=" + id + ", name=" + name + "]";
        }
    
    }

## 3.2 学生类 StudentAnno4.java ##

package com.demo.model4;
    
    import java.util.Date;
    import java.util.HashSet;
    import java.util.Set;
    import javax.persistence.CascadeType;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.JoinTable;
    import javax.persistence.ManyToMany;
    import javax.persistence.Table;
    import javax.persistence.Temporal;
    import javax.persistence.TemporalType;
    import org.hibernate.annotations.Cascade;
    import org.hibernate.annotations.GenericGenerator;
    
    @Entity
    @Table(name = "student_anno4")
    public class StudentAnno4 { 
    
        @Id
        @GenericGenerator(name = "generator",strategy="increment")
        @GeneratedValue(generator="generator")
        @Column(name="sid")
        private Integer sid; // 学生id
    
        @Column(name="name")
        private String name; // 学生姓名
    
        @Column(name="gender")
        private String gender;
    
        @Column(name = "birthday")
        @Temporal(TemporalType.TIMESTAMP)
        private Date birthday;
    
        @ManyToMany(cascade=CascadeType.ALL)
        @JoinTable(name="student_course4",joinColumns={
       @JoinColumn(name="sid")},inverseJoinColumns={
       @JoinColumn(name="id")})
        private Set<CourseAnno4> courses = new HashSet<CourseAnno4>();
    
        public StudentAnno4() {
    
        }
    
        public Integer getSid() {
            return sid;
        }
    
        public void setSid(Integer sid) {
            this.sid = sid;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getGender() {
            return gender;
        }
    
        public void setGender(String gender) {
            this.gender = gender;
        }
    
        public Date getBirthday() {
            return birthday;
        }
    
        public void setBirthday(Date birthday) {
            this.birthday = birthday;
        }
    
        public Set<CourseAnno4> getCourses() {
            return courses;
        }
    
        public void setCourses(Set<CourseAnno4> courses) {
            this.courses = courses;
        }
    
        public String toString() {
            return "Student [sid=" + sid + ", name=" + name + ", gender=" + gender
                    + ", birthday=" + birthday + "]";
        }
    
    }

## 3.3 测试类 TestAnnotation4.java ##

package com.demo.test4;
    
    import java.util.Date;
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.Transaction;
    import org.hibernate.cfg.AnnotationConfiguration;
    import org.hibernate.cfg.Configuration;
    import org.junit.After;
    import org.junit.Before;
    import org.junit.Test;
    import com.demo.model4.CourseAnno4;
    import com.demo.model4.StudentAnno4;
    
    public class TestAnnotation4 { 
        private SessionFactory sessionFactory;
        private Session session;
        private Transaction transaction;
    
        @Before
        public void init(){
            //创建配置对象，加载配置文件 hibernate.cfg.xml
            Configuration configuration = new AnnotationConfiguration().configure();
            //创建会话连接工厂
            sessionFactory = configuration.buildSessionFactory();
            //打开会话
            session = sessionFactory.openSession();
            //开启事务
            transaction = session.beginTransaction();
        }
    
        @After
        public void destory(){
            //提交事务
            transaction.commit();
            //关闭会话
            session.close();
            //关闭工厂会话连接
            sessionFactory.close();
    
        }
    
        /** * 新增学生信息 */
        @Test
        public void testSaveStudent() {
            StudentAnno4 stu = new StudentAnno4();
            stu.setName("张三丰");
            stu.setGender("男");
            stu.setBirthday(new Date());
    
            StudentAnno4 stu2 = new StudentAnno4();
            stu2.setName("张三丰");
            stu2.setGender("男");
            stu2.setBirthday(new Date());
    
            CourseAnno4 cou1 = new CourseAnno4();
            cou1.setName("java");
    
            CourseAnno4 cou2 = new CourseAnno4();
            cou2.setName("c");
    
            stu.getCourses().add(cou1);
            stu.getCourses().add(cou2);
            stu2.getCourses().add(cou1);
            stu2.getCourses().add(cou2);
    
    
            session.save(stu);
            session.save(stu2);
    
        }
    
        /** * 更新学生信息 */
        @Test
        public void testUpdateStu() {
            // 获取一个学生对象
            StudentAnno4 stu = (StudentAnno4) session.get(StudentAnno4.class, 1);
            stu.setName("张峰");
            session.save(stu);
        }
    
        /** * 删除学生信息 */
        @Test
        public void testDeleteStu() {
            StudentAnno4 stu = (StudentAnno4) session.get(StudentAnno4.class, 1);
            session.delete(stu);
        }
    
        /** * 查询学生信息 */
        @Test
        public void testGetStu() {
            StudentAnno4 stu = (StudentAnno4) session.get(StudentAnno4.class, 1);
            System.out.println(stu);
        }
    
    }

# 4.附：hibernate配置文件hibernate.cfg.xml和pom.xml #

## 4.1 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>
            
            <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
            <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8</property>
            <property name="hibernate.connection.username">root</property>
            <property name="hibernate.connection.password">123456</property>
            <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
            <property name="hibernate.show_sql">true</property>
            <property name="hibernate.format_sql">true</property>
            <property name="hbm2ddl.auto">update</property>
    
            
            <mapping class="com.demo.model.StudentAnno" />
            <mapping class="com.demo.model.CourseAnno" />
    
            <mapping class="com.demo.model3.StudentAnno3" />
            <mapping class="com.demo.model3.CourseAnno3" />
    
            <mapping class="com.demo.model4.StudentAnno4" />
            <mapping class="com.demo.model4.CourseAnno4" />
    
        </session-factory>
    
    </hibernate-configuration>

## 4.2 pom.xml （maven项目需要） ##

<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>chendan</groupId>
        <artifactId>hibernateTest</artifactId>
        <packaging>war</packaging>
        <version>0.0.1-SNAPSHOT</version>
        <name>hibernateTest Maven Webapp</name>
        <url>http://maven.apache.org</url>
    
        <dependencies>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.11</version>
                <scope>test</scope>
            </dependency>
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.6</version>
            </dependency>
            
            <dependency>
                <groupId>org.hibernate</groupId>
                <artifactId>hibernate-core</artifactId>
                <version>3.6.9.Final</version>
            </dependency>
            
            <dependency>
                <groupId>javassist</groupId>
                <artifactId>javassist</artifactId>
                <version>3.12.0.GA</version>
            </dependency>
            <dependency>
                <groupId>commons-lang</groupId>
                <artifactId>commons-lang</artifactId>
                <version>2.6</version>
            </dependency>
            
            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>1.2.16</version>
            </dependency>
            <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>slf4j-log4j12</artifactId>
                <version>1.7.21</version>
                <scope>compile</scope>
            </dependency>
            <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>slf4j-nop</artifactId>
                <version>1.6.0</version>
            </dependency>
        </dependencies>
    
        <build>
            <finalName>hibernateTest</finalName>
        </build>
    </project>