初识Hibernate的几种方式

柔光的暖阳◎ 2022-09-21 11:58 181阅读 0赞

1，实体类与数据库表映射关系  
  
   1>可以采用注解的方式；  
  
   2>可以使用配置文件配置映射关系；  
  
2，配置文件  
  
   1>hibenate.properties；  
  
   2>hibernate.cfg.xml(其他命名方式)；  
  
   3>不使用配置文件；  
  
3，核心代码加载加载配置文件  
  
   1>直接加载配置文件；  
     
   2>使用addAnnotatedClass()方法；  
     
   3>使用addPackage()方法；  
     
     
以上这些方式组合使用，有的组合可以正常，有的不可使用，下面仅提供可用例子，未提供的组合均未测试成功

例子测试：

1.注解+hibernate.cfg.xml+直接加载配置文件

实体类

package com.anlw.entity;
    
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.Table;
    
    @Entity
    @Table(name="student")
    public class Student {
        @Id
        @GeneratedValue(strategy=GenerationType.IDENTITY)
        //主键的类型最好使用基本类型的包装类型
        private Integer id;
        private String name;
        private Integer age;
        public Student(){}
        public Student(Integer id, String name, Integer age) {
            this.id = id;
            this.name = name;
            this.age = age;
        }
        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 Integer getAge() {
            return age;
        }
        public void setAge(Integer age) {
            this.age = age;
        }
        
    }

配置文件

<?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="show_sql">true</property>
    		<property name="connection.url">jdbc:mysql://localhost:3306/bookshop</property>
    		<property name="connection.username">root</property>
    		<property name="connection.password">123456</property>
    		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
    		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    		<property name="hibernate.format_sql">true</property>
    		<property name="hbm2ddl.auto">update</property>
    		<mapping class="com.anlw.entity.Student"/>
    	</session-factory>
    </hibernate-configuration>

核心测试代码

package com.anlw.test;
    
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.Transaction;
    import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
    import org.hibernate.cfg.Configuration;
    import org.hibernate.service.ServiceRegistry;
    
    import com.anlw.entity.Student;
    
    public class Test {
    	public static void main(String[] args) {
    		//如果调用configure()，则默认加载根目录下的hibernate.cfg.cml,如果添加参数
    		//.configure("com/anlw/test/aa.xml);则是在对应的路径下寻找该名称的配置文件
    		Configuration conf = new Configuration().configure();
    		ServiceRegistry st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
    		SessionFactory sf = conf.buildSessionFactory(st);
    		Session sess = sf.openSession();
    		Transaction tx = sess.beginTransaction();
    		Student s1 = new Student(1, "Name1", 19);
    		sess.save(s1);
    		tx.commit();
    		sess.close();
    		sf.close();
    	}
    }

2.映射文件+hibernate.cfg.xml+直接加载配置文件  
实体类

package com.anlw.entity;
    
    public class Student {
    	private Integer id;
    	private String name;
    	private String sex;
    	public Student() {
    	}
    	public Student(Integer id, String name, String sex) {
    		super();
    		this.id = id;
    		this.name = name;
    		this.sex = sex;
    	}
    	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 String getSex() {
    		return sex;
    	}
    	public void setSex(String sex) {
    		this.sex = sex;
    	}
    }

实体类与关系数据表的映射

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
    <hibernate-mapping>
        <class name="com.anlw.entity.Student" table="student" catalog="bookshop">
            <id name="id" type="java.lang.Integer">
                <column name="Id" />
                <generator class="native" />
            </id>
            <property name="name" type="java.lang.String">
                <column name="name" length="50" />
            </property>
            <property name="sex" type="java.lang.String">
                <column name="sex" length="255" />
            </property>
        </class>
    </hibernate-mapping>

配置文件

<?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="show_sql">true</property>
    		<property name="connection.url">jdbc:mysql://localhost:3306/bookshop</property>
    		<property name="connection.username">root</property>
    		<property name="connection.password">123456</property>
    		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
    		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    		<property name="hibernate.format_sql">true</property>
    		<property name="hbm2ddl.auto">update</property>
    		<mapping resource="Student.xml"/>
    	</session-factory>
    </hibernate-configuration>

核心代码

package com.anlw.test;
    
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.Transaction;
    import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
    import org.hibernate.cfg.Configuration;
    import org.hibernate.service.ServiceRegistry;
    
    import com.anlw.entity.Student;
    
    public class Test {
    	public static void main(String[] args) {
    		//如果调用configure()，则默认加载根目录下的hibernate.cfg.cml,如果添加参数
    		//.configure("com/anlw/test/aa.xml);则是在对应的路径下寻找该名称的配置文件
    		Configuration conf = new Configuration().configure();
    		ServiceRegistry st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
    		SessionFactory sf = conf.buildSessionFactory(st);
    		Session sess = sf.openSession();
    		Transaction tx = sess.beginTransaction();
    		Student s1 = new Student(1, "Name2", "boy");
    		sess.save(s1);
    		tx.commit();
    		sess.close();
    		sf.close();
    
    	}
    }

3.注解+无配置文件+addAnnotatedClass()

实体类

package com.anlw.entity;
    
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.Table;
    
    @Entity
    @Table(name="student")
    public class Student {
    	@Id
    	@GeneratedValue(strategy=GenerationType.IDENTITY)
    	private Integer id;
    	private String name;
    	private Integer age;
    	//public Student(){}
    	public Student(Integer id, String name, Integer age) {
    		this.id = id;
    		this.name = name;
    		this.age = age;
    	}
    	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 Integer getAge() {
    		return age;
    	}
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    	
    }

核心代码

package com.anlw.entity;
    
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.Transaction;
    import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
    import org.hibernate.cfg.Configuration;
    import org.hibernate.service.ServiceRegistry;
    
    public class Test {
    	public static void main(String[] args) {
    		Configuration conf = new Configuration().addAnnotatedClass(Student.class)
    				.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLDialect")
    				.setProperty("hibernate.connection.driver_class", "com.mysql.jdbc.Driver")
    				.setProperty("hibernate.connection.url", "jdbc:mysql://localhost:3306/bookshop")
    				.setProperty("hibernate.connection.username", "root")
    				.setProperty("hibernate.connection.password", "123456")
    				.setProperty("hibernate.hbm2ddl.auto", "update");
    		ServiceRegistry se = new StandardServiceRegistryBuilder()
    				.applySettings(conf.getProperties()).build();
    		SessionFactory sf = conf.buildSessionFactory(se);
    		Session sess = sf.openSession();
    		Transaction tx = sess.beginTransaction();
    		Student st = new Student(1, "anlw", 25);
    		sess.save(st);
    		tx.commit();
    		sess.close();
    		sf.close();	
    	}
    }

4.注解+hibenate.properties+addAnnotatedClass()

hibenate.properties必须放src根目录下

实体类

package com.anlw.entity;
    
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.Table;
    
    @Entity
    @Table(name="student")
    public class Student {
    	@Id
    	@GeneratedValue(strategy=GenerationType.IDENTITY)
    	private Integer id;
    	private String name;
    	private Integer age;
    	//public Student(){}
    	public Student(Integer id, String name, Integer age) {
    		this.id = id;
    		this.name = name;
    		this.age = age;
    	}
    	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 Integer getAge() {
    		return age;
    	}
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    	
    }

hibenate.properties

hibernate.dialect org.hibernate.dialect.MySQLDialect
    hibernate.connection.driver_class com.mysql.jdbc.Driver
    hibernate.connection.url:jdbc:mysql://localhost:3306/bookshop
    hibernate.connection.username root
    hibernate.connection.password=123456
    hibernate.hbm2ddl.auto create
    hibernate.show_sql=true
    hibernate.hibernate.format_sql true

注意：properties文件的连接符可以是空格，也可以是=，也可以是：。

核心代码

注：hibernate.properties和无配置文件可以混合使用。