Hibernate 注解映射使用方式案例

客官°小女子只卖身不卖艺 2022-06-07 14:08 210阅读 0赞

**Hibernate 注解映射使用方式案例**

本案例使用的hibernate版本为 hibernate-release-5.2.10.Final

为了测试，本案例在mysql数据库中创建了一个db数据库。

创建一个java项目：项目的结构如下：（lib文件夹用于存放jar包）

![Center][]

lib目录下则是hibernate5需要的jar包（注需要将jar加载到项目中：选中jar包右键 --》BuildPath--》Add to Build Path）  
![Center 1][]  
log4j.properties为日志配置文件（需要加载配置junit），此项目可以不需要日志，使用日志只是为了观察方便。  
注：junit配置可以参考 [http://blog.csdn.net/benxiaohai888/article/details/78231911][http_blog.csdn.net_benxiaohai888_article_details_78231911]

由于在主配置文件配置了字段创建数据表的配置，所以第一次加载时就会自动创建数据表

配置的代码：

<property name="hbm2ddl.auto">update</property>

接下来是示例代码：

1、主配置文件 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/db?characterEncoding=utf8</property>
    		
    		<property name="hibernate.connection.username">root</property>
    		
    		<property name="hibernate.connection.password"></property>
    
    		
    		<property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
    
    		
    
    		
    
    		
    		<property name="hibernate.show_sql">true</property>
    		
    		<property name="hibernate.format_sql">true</property>
    		
    		<property name="hbm2ddl.auto">update</property>
    		
    		<property name="hibernate.current_session_context_class">thread</property>
    		
    		<property name="hibernate.connection.isolation">4</property>
    
    		
    		
    		<mapping class="cn.sz.vo.User" />
    
    	</session-factory>
    </hibernate-configuration>

2、工具类（获取Session）HibernateUtil.java

package cn.sz.utils;
    
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.cfg.Configuration;
    
    public class HibernateUtil {
    	public static Session getSession() {
    		Session session = null;
    		// 创建一个读取主配置文件的对象
    		Configuration cfg = new Configuration();
    		// 读取主配置文件
    		// cfg.configure("hibernate.cfg.xml");如果读取的主配置文件时默认的名字则可以省略参数
    		cfg.configure();
    		// 创建SessionFactory
    		SessionFactory factory = cfg.buildSessionFactory();
    		// 打开session
    		// 我们在主配置中已经将session绑定到线程中，所以可以从线程中取出session
    		// 不从线程中取出session，则可以使用 factory.openSession(); 方式获得session
    		session = factory.getCurrentSession();
    		return session;
    
    	}
    
    }

3、日志文件 log4j.properties

log4j.rootLogger=DEBUG,console,FILE
    log4j.appender.console=org.apache.log4j.ConsoleAppender
    log4j.appender.console.threshold=INFO
    log4j.appender.console.layout=org.apache.log4j.PatternLayout
    log4j.appender.console.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} [%5p] - %c -%F(%L) -%m%n
    log4j.appender.FILE=org.apache.log4j.RollingFileAppender
    log4j.appender.FILE.maxBackupIndex=100
    ##log4j.appender.FILE=org.apache.log4j.DailyRollingFileAppender 
    log4j.appender.FILE.Append=true
    log4j.appender.FILE.File=c:/error1.log
    log4j.appender.FILE.Threshold=INFO
    log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
    log4j.appender.FILE.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} [%5p] - %c -%F(%L) -%m%n
    log4j.appender.FILE.MaxFileSize=1MB

4、实体类 User.java

package cn.sz.vo;
    
    import java.math.BigDecimal;
    import java.util.Date;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    
    import javax.persistence.Column;
    import javax.persistence.ElementCollection;
    import javax.persistence.Entity;
    import javax.persistence.FetchType;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.JoinTable;
    import javax.persistence.Lob;
    import javax.persistence.MapKeyColumn;
    import javax.persistence.OrderColumn;
    import javax.persistence.Table;
    import javax.persistence.Temporal;
    import javax.persistence.TemporalType;
    
    import org.hibernate.annotations.GenericGenerator;
    import org.hibernate.annotations.Type;
    
    @Entity // 告诉框架本类参与映射配置，必要
    @Table(name = "user") // 用于配制表名称，当省略时类名称与表名称一致
    public class User {
    	@Id // 用于配制主属性
    	@GeneratedValue(strategy = GenerationType.AUTO) // 配置数值类型的主键生成策略
    	private Integer uid;
    
    	// uuid的主键生成策略
    	// @Id
    	// @GeneratedValue(generator = "uuid")
    	// @GenericGenerator(name = "uuid", strategy = "uuid")
    	// private String uid;
    
    	// @Transient //用于将实体类中的指定属性设置为不参与映射配置
    	@Column(name = "username", length = 30) // 用于映射配制属性名和字段名的长度
    	private String uname;
    
    	@Lob // 配置大对象类型
    	private String content;
    
    	@Temporal(TemporalType.DATE) // 配置日期类型
    	private Date birthday;
    
    	@Temporal(TemporalType.TIMESTAMP) // 配置日时间类型
    	private Date usertime;
    
    	@Type(type = "byte[]") // 配置类型，可选hibernate类型或者Java类型
    	@Column(name = "icon", length = 1024000)
    	private byte[] photo;
    
    	@Column(columnDefinition = "double(10,2) default '1.00'") // double类型10位，2位小数，默认值为1.00
    	private Double sal;
    
    	@Column(precision = 7, scale = 2)
    	private BigDecimal comm;
    
    	// Set集合属性
    	@ElementCollection(fetch = FetchType.LAZY) // 检索策略：懒加载
    	@JoinTable(name = "t_set", joinColumns = @JoinColumn(name = "uid"))
    	@Column(name = "address")
    	private Set<String> setAddress;
    
    	// List集合属性
    	@ElementCollection(fetch = FetchType.LAZY)
    	@JoinTable(name = "t_list", joinColumns = @JoinColumn(name = "uid"))
    	@OrderColumn(name = "idx")
    	@Column(name = "address")
    	private List<String> listAddress;
    
    	// 数组属性
    	@ElementCollection(fetch = FetchType.LAZY)
    	@JoinTable(name = "t_arr", joinColumns = @JoinColumn(name = "uid"))
    	@OrderColumn(name = "idx")
    	@Column(name = "address")
    	private String[] arrayStr;
    
    	// Map属性
    	@ElementCollection(fetch = FetchType.LAZY)
    	@JoinTable(name = "t_map", joinColumns = @JoinColumn(name = "uid"))
    	@MapKeyColumn(name = "key_")
    	@Column(name = "address")
    	private Map<String, String> mapAddress;
    
    	public BigDecimal getComm() {
    		return comm;
    	}
    
    	public void setComm(BigDecimal comm) {
    		this.comm = comm;
    	}
    
    	public Set<String> getSetAddress() {
    		return setAddress;
    	}
    
    	public void setSetAddress(Set<String> setAddress) {
    		this.setAddress = setAddress;
    	}
    
    	public List<String> getListAddress() {
    		return listAddress;
    	}
    
    	public void setListAddress(List<String> listAddress) {
    		this.listAddress = listAddress;
    	}
    
    	public String[] getArrayStr() {
    		return arrayStr;
    	}
    
    	public void setArrayStr(String[] arrayStr) {
    		this.arrayStr = arrayStr;
    	}
    
    	public Map<String, String> getMapAddress() {
    		return mapAddress;
    	}
    
    	public void setMapAddress(Map<String, String> mapAddress) {
    		this.mapAddress = mapAddress;
    	}
    
    	// public Integer getUid() {
    	// return uid;
    	// }
    	//
    	// public void setUid(Integer uid) {
    	// this.uid = uid;
    	// }
    
    	public String getUname() {
    		return uname;
    	}
    
    	public void setUname(String uname) {
    		this.uname = uname;
    	}
    
    	public String getContent() {
    		return content;
    	}
    
    	public void setContent(String content) {
    		this.content = content;
    	}
    
    	public Date getBirthday() {
    		return birthday;
    	}
    
    	public void setBirthday(Date birthday) {
    		this.birthday = birthday;
    	}
    
    	public Date getUsertime() {
    		return usertime;
    	}
    
    	public void setUsertime(Date usertime) {
    		this.usertime = usertime;
    	}
    
    	public byte[] getPhoto() {
    		return photo;
    	}
    
    	public void setPhoto(byte[] photo) {
    		this.photo = photo;
    	}
    
    	public Double getSal() {
    		return sal;
    	}
    
    	public void setSal(Double sal) {
    		this.sal = sal;
    	}
    
    }

5、测试类

package cn.sz.test;
    
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.HashMap;
    import java.util.HashSet;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    
    import org.hibernate.Session;
    import org.junit.Test;
    
    import cn.sz.utils.HibernateUtil;
    import cn.sz.vo.User;
    
    public class UserTest {
    
    	@Test
    	public void testSave() {
    		Session session = HibernateUtil.getSession();
    		session.beginTransaction();
    		// 创建一个用户
    		User u = new User();
    		u.setUname("张三");
    		u.setContent("张三的个人简介");
    		u.setBirthday(new Date());
    		u.setSal(1000.2266);
    
    		// 创建Map集合
    		Map<String, String> map = new HashMap<>();
    		map.put("a1", "北京");
    		map.put("a2", "上海");
    		// 将map集合绑定到用户
    		u.setMapAddress(map);
    
    		// 创建List集合
    		List<String> list = new ArrayList<>();
    		list.add("南京");
    		list.add("昆明");
    		// 将List集合绑定到用户
    		u.setListAddress(list);
    
    		// 创建Set集合
    		Set<String> set = new HashSet<>();
    		set.add("西藏");
    		set.add("深圳");
    		// 将set集合绑定到用户
    		u.setSetAddress(set);
    
    		// 创建数组
    		String[] arr = new String[2];
    		arr[0] = "龙华";
    		arr[1] = "澳门";
    		// 将数组绑定到用户
    		u.setArrayStr(arr);
    
    		session.save(u);
    		session.getTransaction().commit();
    		session.close();
    	}
    }

由于我们配置了字段生成数据表的配置，所以在第一次测试时，将创建数据表，数据表的结构如下（每张表设置了t\_为前缀）：

总体预览：

![Center 2][]

数组属性生成的表 t\_arr:

![Center 3][]

List属性生成的表 t\_list:

![Center 4][]

set属性生成的表 t\_set:

![Center 5][]

map属性生成的表t\_map

![Center 6][]

user表：

![Center 7][]

[Center]: /images/20220607/c29dc12c68b14a229e705757a5575bb1.png
[Center 1]: /images/20220607/4d9ad29a77d845cb92c6dab692db5b1e.png
[http_blog.csdn.net_benxiaohai888_article_details_78231911]: http://blog.csdn.net/benxiaohai888/article/details/78231911
[Center 2]: /images/20220607/0a43ad3c39c24093abf4922c4560c365.png
[Center 3]: /images/20220607/f9263b35a1ca4a1cb5be38853ae25ed2.png
[Center 4]: /images/20220607/6a8387de34bd47afa1e57426cbc394b5.png
[Center 5]: /images/20220607/0c1dde3dc1ea4e13a03fb10ee59692ae.png
[Center 6]: /images/20220607/96c8cb2859744bf6a25d12b5ea8f5943.png
[Center 7]: /images/20220607/4f1ea73ec6bc4289b5466f051ed2dd6c.png