Hibernate 中的多对多的关系：

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Hibernate log4j Myeclipse XML JDBC

作者：shazi.

数据库的生成由配置文件自动生成。例子中两个实体类，学生类和教师类。一个学生可以由多个教师，一个教师也可以有多个学生。

主要代码如下：

（一）配置文件：hibernate-cfg.xml

xml 代码

<?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="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="connection.url">
jdbc:mysql://localhost:3306/good
</property>
<property name="connection.username">root</property>
<property name="connection.password">admin</property>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="myeclipse.connection.profile">
database
</property>
<property name="show_sql">true</property>
<property name="jdbc.fetch_size">50</property>
<property name="jdbc.batch_size">25</property>
<property name="hbm2ddl.auto">true</property>
<mapping resource="mapping/student.hbm.xml" />
<mapping resource="mapping/teacher.hbm.xml" />
</session-factory>
</hibernate-configuration>

（二）日志文件：log4j.xml

xml 代码

### 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{1}:%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=info, stdout
#log4j.logger.org.hibernate=info
log4j.logger.org.hibernate=info
### 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

（三）HibernateSessionFactory.java文件，主要是SessionFactory的创建和Session的创建。

java 代码

package dao;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
/**
* Configures and provides access to Hibernate sessions, tied to the
* current thread of execution. Follows the Thread Local Session
* pattern, see {@link http://hibernate.org/42.html }.
*/
public class HibernateSessionFactory {
/**
* Location of hibernate.cfg.xml file.
* Location should be on the classpath as Hibernate uses
* #resourceAsStream style lookup for its configuration file.
* The default classpath location of the hibernate config file is
* in the default package. Use #setConfigFile() to update
* the location of the configuration file for the current session.
*/
private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
private static Configuration configuration = new Configuration();
private static org.hibernate.SessionFactory sessionFactory;
private static String configFile = CONFIG_FILE_LOCATION;
private HibernateSessionFactory() {
}
/**
* Returns the ThreadLocal Session instance. Lazy initialize
* the <code>SessionFactory</code> if needed.
*
* @return Session
* @throws HibernateException
*/
public static Session getSession() throws HibernateException {
Session session = (Session) threadLocal.get();
if (session == null || !session.isOpen()) {
if (sessionFactory == null) {
rebuildSessionFactory();
}
session = (sessionFactory != null) ? sessionFactory.openSession()
: null;
threadLocal.set(session);
}
return session;
}
/**
* Rebuild hibernate session factory
*
*/
public static void rebuildSessionFactory() {
try {
configuration.configure(configFile);
sessionFactory = configuration.buildSessionFactory();
} catch (Exception e) {
System.err
.println("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
}
/**
* Close the single hibernate session instance.
*
* @throws HibernateException
*/
public static void closeSession() throws HibernateException {
Session session = (Session) threadLocal.get();
threadLocal.set(null);
if (session != null) {
session.close();
}
}
/**
* return session factory
*
*/
public static org.hibernate.SessionFactory getSessionFactory() {
return sessionFactory;
}
/**
* return session factory
*
* session factory will be rebuilded in the next call
*/
public static void setConfigFile(String configFile) {
HibernateSessionFactory.configFile = configFile;
sessionFactory = null;
}
/**
* return hibernate configuration
*
*/
public static Configuration getConfiguration() {
return configuration;
}
}

(四) 创建Student.java，POJO类。

java 代码

package mapping;
import java.util.HashSet;
import java.util.Set;
public class Student implements java.io.Serializable{
private Integer id;
private String name;
private Set teacher=new HashSet();
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Set getTeacher() {
return teacher;
}
public void setTeacher(Set teacher) {
this.teacher = teacher;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}

（五）student.hbm.xml

xml 代码

<?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">
<!--
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping>
<class name="mapping.Student" table="student">
<id name="id" type="integer">
<column name="ID" />
<generator class="identity"></generator>
</id>
<property name="name" type="string">
<column name="name" length="100" />
</property>
<set name="teacher" inverse="true" cascade="save-update" table="student_teacher">
<key column="s_id" not-null="false">
</key>
<many-to-many class="mapping.Teacher" column="t_id" outer-join="true" />
</set>
</class>
</hibernate-mapping>

（六）Teacher.java

java 代码

package mapping;
import java.util.HashSet;
import java.util.Set;
/**
* Teacher generated by MyEclipse - Hibernate Tools
*/
public class Teacher extends mapping.Student implements java.io.Serializable {
// Fields
private Integer id;
private String name;
private Set students = new HashSet(0);
// Constructors
/** default constructor */
public Teacher() {
}
/** full constructor */
public Teacher(String name, Set students) {
this.name = name;
this.students = students;
}
// Property accessors
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public Set getStudents() {
return this.students;
}
public void setStudents(Set students) {
this.students = students;
}
}

(七)teacher.bhm.xml

xml 代码

<?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">
<!--
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping>
<class name="mapping.Teacher" table="teacher">
<id name="id" type="integer">
<column name="id" />
<generator class="native"></generator>
</id>
<property name="name" type="string">
<column name="name" length="100" />
</property>
<set name="students" cascade="save-update" table="student_teacher">
<key column="t_id" not-null="false">
</key>
<many-to-many class="mapping.Student" column="s_id" outer-join="true"/>
</set>
</class>
</hibernate-mapping>

（八）测试类：Test.java,使用SchemaExport schemaExport = new SchemaExport(config);生成数据库代码。

java 代码

package dao;
import mapping.Student;
import mapping.Teacher;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.tool.hbm2ddl.SchemaExport;
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
org.hibernate.cfg.Configuration config=new org.hibernate.cfg.Configuration().configure();
System.out.println("Creating tables...");
SchemaExport schemaExport = new SchemaExport(config);
schemaExport.create(true, true);
System.out.println("Table created.");
Student s = new Student();
s.setName("rose");
Teacher t = new Teacher();
t.setName("admin");
s.getTeacher().add(t);
t.getStudents().add(s);
Session session = HibernateSessionFactory.getSession();
Transaction tx = session.beginTransaction();
session.save(t);
session.save(s);
tx.commit();
session.close();
}
}

运行即可：

manytomany.rar (38.9 KB)
下载次数: 40

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Hibernate 的Xdoclet模板 | 通用数据权限管理系统设计

2007-07-19 23:41
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评论(1)
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1 楼 meadlai 2008-11-02

student_teacher表中有外键吧?
这个表应该有xml配置吧?

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