Hibernate学习（三）

映射基础
（1）基本实体映射技术类和表映射<hibernate-mapping package="hibernate.test.domain"> <class name="Student" table="student" lazy="true"></class></hibernate-mapping>主键映射<id name="id"><generator class="uuid"/></id>普通字段映射<property name="sNo" column="sno" not-null="true" type="java.lang.String"></property> （2）多个字段作为主键第一步：建立实体（Book）多个字段作为主键时，需要重新建一个类，包含作为主键的各个字段。在这里命名为BookName。//多个字段做主键//Composite-id class must implement Serializablepublic class BookName implements Serializable{/** * */private static final long serialVersionUID = 1L;private String name;private String author;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getAuthor() {return author;}public void setAuthor(String author) {this.author = author;}public BookName() {super();// TODO Auto-generated constructor stub}public BookName(String name, String author) {super();this.name = name;this.author = author;}
}Book类：package hibernate.test.domain; public class Book {private BookName id;private String shortShow;private String picture;private String content;
public void setId(BookName id) {this.id = id;}public BookName getId() {return id;}public String getShortShow() {return shortShow;}public void setShortShow(String shortShow) {this.shortShow = shortShow;}public String getPicture() {return picture;}public void setPicture(String picture) {this.picture = picture;}public String getContent() {return content;}public void setContent(String content) {this.content = content;}
} 第二步: 映射文件（Book.hbm.xml）<?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 package="hibernate.test.domain"> <class name="Book" table="Book" lazy="true"><composite-id name="id" class="BookName"><key-property name="name" type="java.lang.String" column="name"></key-property><key-property name="author" type="java.lang.String" column="author"></key-property></composite-id><property name="shortShow" column="shortShow" type="java.lang.String"></property><property name="picture" column="picture" type="java.lang.String"></property><property name="content" column="content" type="java.lang.String"></property></class></hibernate-mapping>第三步：配置文件在mapping下添加映射文件位置：<mapping resource="hibernate/test/xml/Book.hbm.xml"></mapping>第四部：测试 插入数据public static void main(String[] args) { Session session=null; Transaction tx=null; try { session=HibernateUtil.getSession(); tx=session.beginTransaction(); BookName bookName=new BookName("快乐是本","ytt"); Book book=new Book(); book.setId(bookName); book.setPicture("http://"); book.setShortShow("简单介绍"); book.setContent("介绍内容"); session.save(book); tx.commit(); } catch (Exception e) { // TODO: handle exception if(tx!=null) tx.rollback(); } finally{ if(session!=null) session.close(); } }数据库验证，插入成功！ （3）组合关系映射（会产生很多冗余数据，大多还是通过一对多，多对多进行设计）第一步 类的建立public class Address {private String city;private String street;private String zipcode;public String getCity() {return city;}public void setCity(String city) {this.city = city;}public String getStreet() {return street;}public void setStreet(String street) {this.street = street;}public String getZipcode() {return zipcode;}public void setZipcode(String zipcode) {this.zipcode = zipcode;}public Address(String city, String street, String zipcode) {super();this.city = city;this.street = street;this.zipcode = zipcode;}public Address() {super();// TODO Auto-generated constructor stub}//组合关系测试public class Person {private int id;private String name;private Address address;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 Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}}第二步 映射文件<?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 package="hibernate.test.domain"> <class name="Person" table="Person" lazy="true"><id name="id"><generator class="native"></generator></id><property name="name"></property><component name="address" class="Address"><property name="city"></property><property name="street"></property><property name="zipcode"></property></component></class></hibernate-mapping>第三步 配置文件 <mapping resource="hibernate/test/xml/Person.hbm.xml"></mapping>第四步 测试public static void main(String[] args) {// TODO Auto-generated method stubSession session=null;Transaction tx=null;try {session=HibernateUtil.getSession();tx=session.beginTransaction();Address address=new Address("郑州", "商都路G107国道", "0371");Person person=new Person();person.setName("ytt");person.setAddress(address);session.save(person);tx.commit();} catch (Exception e) {// TODO: handle exceptionif(tx!=null){tx.rollback();}}finally{session.close();}} 实际上是一张表，插入语句时这个：Hibernate: insert into Person (name, city, street, zipcode) values (?, ?, ?, ?) （4）大对象映射Clob 文本大对象 最长4GBlob 二进制数据大对象 最长4G这个也不是很常用，就像其他类型一样使用，在映射文件中，type改为“java.sql.Blob/Clob”就行。