一 List映射
如果持久化类中具有List对象，可以通过映射文件中的类<list>元素或注解来映射List.
例如，一个问题有多个答案：
1）创建持久化类
package list;import java.util.List;public class Question { private int id; private String qname; private List<String> answers; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getQname() { return qname; } public void setQname(String qname) { this.qname = qname; } public List<String> getAnswers() { return answers; } public void setAnswers(List<String> answers) { this.answers = answers; } }
2）创建映射文件
<?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> <class name="list.Question" table="quesion"> <cache usage="read-write"/> <id name="id"> <generator class="increment"></generator> </id> <property name="qname"></property> <list name="answers" table="answers"> <key column="qid"></key> <index column="type"></index> <element column="answer" type="string"></element> </list> </class> </hibernate-mapping>
3)在全局配置文件中增加
<!-- List of XML mapping files --> <mapping resource="list/Question.hbm.xml"/>
4）测试
package list;import java.util.ArrayList;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;public class Test { public static void main(String[] args) { Configuration cfg = new Configuration(); cfg.configure("hibernate.cfg.xml"); SessionFactory factory = cfg.buildSessionFactory(); Session session = factory.openSession(); session.beginTransaction(); ArrayList<String> list1 = new ArrayList<String>(); list1.add("answer1"); list1.add("answer2"); Question question1 = new Question(); question1.setQname("question1"); question1.setAnswers(list1); session.save(question1); session.getTransaction().commit(); session.close(); //factory.close(); }}
二 List一对多映射
一个问题有多个答案，每个答案有自己的信息，需要使用一对多关联来映射。
1）创建持久化类
package list;import java.util.List;public class Question { private int id; private String qname; private List<Answer> answers; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getQname() { return qname; } public void setQname(String qname) { this.qname = qname; } public List<Answer> getAnswers() { return answers; } public void setAnswers(List<Answer> answers) { this.answers = answers; } }
package list;public class Answer { private int id; private String answername; private String postedBy; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getAnswername() { return answername; } public void setAnswername(String answername) { this.answername = answername; } public String getPostedBy() { return postedBy; } public void setPostedBy(String postedBy) { this.postedBy = postedBy; } }
2）配置文件
<?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> <class name="list.Question" table="quesion"> <cache usage="read-write"/> <id name="id"> <generator class="increment"></generator> </id> <property name="qname"></property> <list name="answers" cascade="all"> <key column="qid"></key> <index column="type"></index> <one-to-many class="list.Answer"/> </list> </class> <class name="list.Answer" table="answers"> <cache usage="read-write"/> <id name="id"> <generator class="increment"></generator> </id> <property name="answername"></property> <property name="postedBy"></property> </class> </hibernate-mapping>
3）在hibernate.cfg.xml中添加配置
<!-- List of XML mapping files --> <mapping resource="list/Question.hbm.xml"/>
4)测试
package list;import java.util.ArrayList;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;public class Test { public static void main(String[] args) { Configuration cfg = new Configuration(); cfg.configure("hibernate.cfg.xml"); SessionFactory factory = cfg.buildSessionFactory(); Session session = factory.openSession(); session.beginTransaction(); Answer ans1 = new Answer(); ans1.setAnswername("ans1"); ans1.setPostedBy("post1"); Answer ans2 = new Answer(); ans2.setAnswername("ans2"); ans2.setPostedBy("post2"); Answer ans3 = new Answer(); ans3.setAnswername("ans3"); ans3.setPostedBy("post3"); Ar<div>本文来源gaodai^.ma#com搞#代!码网</div>rayList<Answer> list1 = new ArrayList<Answer>(); list1.add(ans1); list1.add(ans2); list1.add(ans3); Question question1 = new Question(); question1.setQname("question1"); question1.setAnswers(list1); session.save(question1); session.getTransaction().commit(); session.close(); //factory.close(); }}
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