hibernate 一對多雙向的CURD

轉自尚學堂教學視頻

 

package com.bjsxt.hibernate;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="t_group")
public class Group {
    private int id;
    private String name;
    private Set<User> users = new HashSet<User>();
    @Id
    @GeneratedValue
    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;
    }
    @OneToMany(mappedBy="group",
        cascade={CascadeType.ALL}//級聯，對user的任何增刪改操做都會影響到該表
        )//還有一個屬性fetch=FetchType.EAGER/LAZY 設置了能夠控制查詢該表的時候是否把它關聯表中它關聯的部分的內容也都查出來。
    //一對多中，一默認的是LAZY就是不取，多默認的是EAGER就是取關聯表的內容
   
    public Set<User> getUsers() {
        return users;
    }
    public void setUsers(Set<User> users) {
        this.users = users;
    }
}

 

 

 

package com.bjsxt.hibernate;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name="t_user")
public class User {
    private int id;
    private String name;
    private Group group;
    @ManyToOne(cascade={CascadeType.ALL})
    public Group getGroup() {
        return group;
    }
    public void setGroup(Group group) {
        this.group = group;
    }
    @Id
    @GeneratedValue
    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;
    }
}

 

 

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>
        <property name="connection.username">root</property>
        <property name="connection.password">bjsxt</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
       <!--
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:SXT</property>
        <property name="connection.username">scott</property>
        <property name="connection.password">tiger</property>
          <property name="dialect">org.hibernate.dialect.OracleDialect</property>
       -->

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

       

        <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>

        <!-- Drop and re-create the database schema on startup
        <property name="hbm2ddl.auto">update</property>
         -->
        <!-- 
       
        <mapping resource="com/bjsxt/hibernate/Group.hbm.xml"/>
         <mapping resource="com/bjsxt/hibernate/User.hbm.xml"/>
         -->
         <mapping class="com.bjsxt.hibernate.Group"/>
        <mapping class="com.bjsxt.hibernate.User"/>
       
    </session-factory>

</hibernate-configuration>

 

 

log4j.properties

### direct log messages to stdout ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c:%L - %m%n

### direct messages to file hibernate.log ###
#log4j.appender.file=org.apache.log4j.FileAppender
#log4j.appender.file.File=hibernate.log
#log4j.appender.file.layout=org.apache.log4j.PatternLayout
#log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n

### set log levels - for more verbose logging change 'info' to 'debug' ###

log4j.rootLogger=warn, stdout

#log4j.logger.org.hibernate=info
#log4j.logger.org.hibernate=debug

### log HQL query parser activity
#log4j.logger.org.hibernate.hql.ast.AST=debug

### log just the SQL
#log4j.logger.org.hibernate.SQL=debug

### log JDBC bind parameters ###
#log4j.logger.org.hibernate.type=info
#log4j.logger.org.hibernate.type=debug

### log schema export/update ###
log4j.logger.org.hibernate.tool.hbm2ddl=debug

### log HQL parse trees
#log4j.logger.org.hibernate.hql=debug

### log cache activity ###
#log4j.logger.org.hibernate.cache=debug

### log transaction activity
#log4j.logger.org.hibernate.transaction=debug

### log JDBC resource acquisition
#log4j.logger.org.hibernate.jdbc=debug

### enable the following line if you want to track down connection ###
### leakages when using DriverManagerConnectionProvider ###
#log4j.logger.org.hibernate.connection.DriverManagerConnectionProvider=trace

 

 

 

 

測試例子代碼：

package com.bjsxt.hibernate;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

public class HibernateORMappingTest {     private static SessionFactory sessionFactory;         @BeforeClass     public static void beforeClass() {         new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);         sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();     }     @AfterClass     public static void afterClass() {         sessionFactory.close();     }         @Test     public void testSaveUser() {         User u = new User();         u.setName("u1");         Group g = new Group();         g.setName("g1");         u.setGroup(g);         Session s = sessionFactory.getCurrentSession();         s.beginTransaction();         //s.save(g);         s.save(u);         s.getTransaction().commit();     }         @Test     public void testSaveGroup() {         User u1 = new User();         u1.setName("u1");         User u2 = new User();         u2.setName("u2");         Group g = new Group();         g.setName("g1");         g.getUsers().add(u1);         g.getUsers().add(u2);         u1.setGroup(g);         u2.setGroup(g);         Session s = sessionFactory.getCurrentSession();         s.beginTransaction();         //s.save(g);         s.save(g);         s.getTransaction().commit();     }         @Test     public void testGetUser() {                 testSaveGroup();                 Session s = sessionFactory.getCurrentSession();         s.beginTransaction();         User u = (User)s.get(User.class, 1);                 s.getTransaction().commit();         System.out.println(u.getGroup().getName());//a，這個時候是會報錯的，由於session已經關閉了     }         @Test     public void testLoadUser() {                 testSaveGroup();                 Session s = sessionFactory.getCurrentSession();         s.beginTransaction();         User u = (User)s.load(User.class, 1);         System.out.println(u.getGroup().getName());//b，放在裏面就不會，         //雖然沒有在fetch中設置eager沒有取出來可是當你使用的時候只要session沒有關閉，仍是會去數據庫中取你要的內容，這點load和get同樣。         s.getTransaction().commit();             }         @Test     public void testDeleteUser() {                 testSaveGroup();                 Session s = sessionFactory.getCurrentSession();         s.beginTransaction();         //User u = (User)s.load(User.class, 1);         //u.setGroup(null);         //s.delete(u);         s.createQuery("delete from User u where u.id = 1").executeUpdate();         s.getTransaction().commit();             }         @Test     public void testDeleteGroup() {                 testSaveGroup();                 Session s = sessionFactory.getCurrentSession();         s.beginTransaction();         //User u = (User)s.load(User.class, 1);         //u.setGroup(null);         //s.delete(u);         Group g = (Group)s.load(Group.class, 1);         s.delete(g);         //s.createQuery("delete from User u where u.id = 1").executeUpdate();         s.getTransaction().commit();             }         @Test     public void testUpdateUser() {                 testSaveGroup();                 Session s = sessionFactory.getCurrentSession();         s.beginTransaction();         User u = (User)s.get(User.class, 1);                 s.getTransaction().commit();                 u.setName("user");         u.getGroup().setName("group");                 Session s2 = sessionFactory.getCurrentSession();         s2.beginTransaction();         s2.update(u);                 s2.getTransaction().commit();     }                 @Test     public void testGetGroup() {                 testSaveGroup();                 Session s = sessionFactory.getCurrentSession();         s.beginTransaction();         Group g = (Group)s.get(Group.class, 1);         s.getTransaction().commit();         for(User u : g.getUsers()) {             System.out.println(u.getName());         }     }         @Test     public void testSchemaExport() {         new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);     }         public static void main(String[] args) {         beforeClass();     } }