直接上步骤：
1.修改pom.xml,添加hibernate相关包
<?xml version="1.0" encoding="UTF-8"?> <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/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.htt.hibernate</groupId> <artifactId>Hibernate_Test</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core --> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>5.3.6.Final</version> </dependency> <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.12</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.0</version> </dependency> </dependencies> </project>2.在resources里面添加hibernate.cfg.xml，用于连接数据库
<?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> <!-- Database connection settings --> <property name="connection.driver_class">com.mysql.jdbc.Driver</property> <property name="connection.url">jdbc:mysql://localhost:3306/javaweb?serverTimezone=UTC</property> <property name="connection.username">...</property> <property name="connection.password">...</property> <!-- JDBC connection pool (use the built-in) --> <property name="connection.pool_size">1</property> <!-- SQL dialect --> <property name="dialect">org.hibernate.dialect.MySQLDialect</property> <!-- Enable Hibernate's automatic session context management --> <property name="current_session_context_class">thread</property> <!-- Echo all executed SQL to stdout --> <property name="show_sql">true</property> <!--指定映射文件路径--> <!--<mapping class="UserMod" />--> <mapping resource="Grade.hbm.xml"/> <mapping resource="Student.hbm.xml"/> </session-factory> </hibernate-configuration>3.一对多(班级和和学生)(一对一可看成特殊的一对多)
3.1 创建班级和学生的对应持久化类(//在一方定义一个多方的集合),对于构造函数，根据测试类中的需求进行构造，不过无参构造函数和包含全部参数的构造函数最好都写上
//Grade.java package com.entity; import java.io.Serializable; import java.util.HashSet; import java.util.Set; public class Grade implements Serializable{ private int gid; private String gname; private String gdesc; //一对多时，在一方定义一个多方的集合 private Set<Student> students = new HashSet<Student>(); public Set<Student> getStudents() { return students; } public void setStudents(Set<Student> students) { this.students = students; } public int getGid() { return gid; } public void setGid(int gid) { this.gid = gid; } public String getGname() { return gname; } public void setGname(String gname) { this.gname = gname; } public String getGdesc() { return gdesc; } public void setGdesc(String gdesc) { this.gdesc = gdesc; } public Grade() { } public Grade(int gid, String gname, String gdesc,Set<Student> students) { this.gid = gid; this.gname = gname; this.gdesc = gdesc; this.students = students; } public Grade(String gname, String gdesc) { this.gname = gname; this.gdesc = gdesc; } } //Student.java package com.entity; import java.io.Serializable; public class Student implements Serializable{ private int sid; private String sname; private String sex; //多对一时，在多方定义一个一方的引用 private Grade grade; public Grade getGrade() { return grade; } public void setGrade(Grade grade) { this.grade = grade; } public int getSid() { return sid; } public void setSid(int sid) { this.sid = sid; } public String getSname() { return sname; } public void setSname(String sname) { this.sname = sname; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public Student() { } public Student(String sname, String sex) { this.sname = sname; this.sex = sex; } }3.2.创建Hibrnate对应的映射类
//HibernateUtils.java package com.util; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateUtils { // 1.创建工厂对象; private static SessionFactory sessionFactory; // 2.初始化工厂对象; static { sessionFactory = new Configuration().configure().buildSessionFactory(); } //4.获取sessionFactory public static SessionFactory getSessionFactory(){ return sessionFactory; } // 3.获得Session; public static Session getSession() { return sessionFactory.openSession(); } //4.关闭session public static void closeSession(Session session){ if (session!= null){ session.close(); } } }3.3 3.创建持久化类对应的映射文件
//Grade.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> <class name="com.entity.Grade" table="grade"> <id name="gid" column="gid" type="java.lang.Integer"> <!--设置主键为自增模式--> <generator class="increment"></generator> </id> <property name="gname" type="java.lang.String"> <column name="gname" length="20" not-null="true"></column> </property> <property name="gdesc"> <column name="gdesc"></column> </property> <!--配置单向的一对多关联关系 , inverse为false表示由一方进行关联关系的维护，设置为true表示由多方进行关联关系的维护--> <!--cascade代表级联，设置为all代表对于所有操作都可以进行级联操作。例，在班级表中添加一个班级后，该班级对应的所有学生也会添加到相应的数据库中--> <set name="students" table="student" inverse="false" cascade="all"> <key column="gid"></key> <one-to-many class="com.entity.Student"/> </set> </class> </hibernate-mapping> //Student.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> <class name="com.entity.Student" table="student"> <id name="sid" column="sid" type="java.lang.Integer"> <!--设置主键为自增模式--> <generator class="increment"></generator> </id> <property name="sname" type="java.lang.String"> <column name="sname" length="20" not-null="true"></column> </property> <property name="sex"> <column name="sex"></column> </property> <many-to-one name="grade" class="com.entity.Grade" column="gid"></many-to-one> </class> </hibernate-mapping>3.4 创建测试类测试
//test.java package com.entity; import com.util.HibernateUtils; import org.hibernate.Session; import org.hibernate.Transaction; import java.util.Set; /*单向一对多关系（班级--->学生） * 建立关联关系后，可以方便的从一个对象导航到另一个对象 * 当建立了双向一对多关系后，既可以方便的由学生查找到对应的班级信息，也可以方便的由班级查找到其所包含的学生信息 * */ public class test { public static void main(String[] args){ // add(); // findStudentsByGrade(); update(); } //将学生添加到班级 public static void add(){ Grade g = new Grade("Java一班","Java软件开发一班"); Student stu1 = new Student("张三","男"); Student stu2 = new Student("王兰","女"); //如果希望在学生表中添加对应的班级编号，需要在班级中添加学生，建立关联关系 g.getStudents().add(stu1); g.getStudents().add(stu2); Session session = HibernateUtils.getSession(); Transaction tx = session.beginTransaction(); session.save(g); session.save(stu1); session.save(stu2); tx.commit(); HibernateUtils.closeSession(session); } //查询班级中包含的学生 public static void findStudentsByGrade(){ Session session = HibernateUtils.getSession(); Grade grade = (Grade)session.get(Grade.class,1); System.out.println(grade.getGname()+","+grade.getGdesc()); Set<Student> students = grade.getStudents(); for (Student stu:students){ System.out.println(stu.getSname()+","+stu.getSex()); } } //修改学生信息 public static void update(){ Grade g = new Grade("Java二班","Java软件开发二班");//新建一个班级 Session session = HibernateUtils.getSession(); Transaction tx = session.beginTransaction(); Student stu = (Student) session.get(Student.class,1);//获取id为1的学生信息，将他保存起来 g.getStudents().add(stu);//在新建的班级中加入该学生 session.save(g); tx.commit(); HibernateUtils.closeSession(session); } //删除学生信息 public static void delete(){ Session session = HibernateUtils.getSession(); Transaction tx = session.beginTransaction(); Student stu = (Student)session.get(Student.class,2); session.delete(stu); tx.commit(); HibernateUtils.closeSession(session); } }4.多对多 与一对多类似，后面看情况再写吧。。
