Java的Spring框架中DAO数据访问对象的使用示例

Spring DAO之JDBC

Spring提供的DAO(数据访问对象)支持主要的目的是便于以标准的方式使用不同的数据访问技术， 如JDBC，Hibernate或者JDO等。它不仅可以让你方便地在这些持久化技术间切换， 而且让你在编码的时候不用考虑处理各种技术中特定的异常。
为了便于以一种一致的方式使用各种数据访问技术，如JDBC、JDO和Hibernate， Spring提供了一套抽象DAO类供你扩展。这些抽象类提供了一些方法，通过它们你可以 获得与你当前使用的数据访问技术相关的数据源和其他配置信息。
Dao支持类：
JdbcDaoSupport - JDBC数据访问对象的基类。 需要一个DataSource，同时为子类提供 JdbcTemplate。
HibernateDaoSupport - Hibernate数据访问对象的基类。 需要一个SessionFactory，同时为子类提供 HibernateTemplate。也可以选择直接通过 提供一个HibernateTemplate来初始化， 这样就可以重用后者的设置，例如SessionFactory， flush模式，异常翻译器（exception translator）等等。
JdoDaoSupport - JDO数据访问对象的基类。 需要设置一个PersistenceManagerFactory， 同时为子类提供JdoTemplate。
JpaDaoSupport - JPA数据访问对象的基类。 需要一个EntityManagerFactory，同时 为子类提供JpaTemplate。
本节主要讨论Sping对JdbcDaoSupport的支持。
下面是个例子：

drop table if exists user; /*==============================================================*/ /* Table: user                         */ /*==============================================================*/ create table user (   id          bigint AUTO_INCREMENT not null,   name         varchar(24),   age         int,   primary key (id) );

public class User {   private Integer id;   private String name;   private Integer age;   public Integer getId() {     return id;   }   public void setId(Integer id) {     this.id = id;   }   public String getName() {     return name;   }   public void setName(String name) {     this.name = name;   }   public Integer getAge() {     return age;   }   public void setAge(Integer age) {     this.age = age;   } }

/** * Created by IntelliJ IDEA.<br> * <b>User</b>: leizhimin<br> * <b>Date</b>: 2008-4-22 15:34:36<br> * <b>Note</b>: DAO接口 */ public interface IUserDAO {   public void insert(User user);   public User find(Integer id); }  import javax.sql.DataSource; import java.sql.Connection; import java.sql.SQLException; /** * Created by IntelliJ IDEA.<br> * <b>Note</b>: 基类DAO，提供了数据源注入 */ public class BaseDAO {   private DataSource dataSource;   public DataSource getDataSource() {     return dataSource;   }   public void setDataSource(DataSource dataSource) {     this.dataSource = dataSource;   }   public Connection getConnection() {     Connection conn = null;     try {       conn = dataSource.getConnection();     } catch (SQLException e) {       e.printStackTrace();     }     return conn;   } }  /** * Created by IntelliJ IDEA.<br> * <b>User</b>: leizhimin<br> * <b>Date</b>: 2008-4-22 15:36:04<br> * <b>Note</b>: DAO实现 */ public class UserDAO extends BaseDAO implements IUserDAO {   public JdbcTemplate getJdbcTemplate(){     return new JdbcTemplate(getDataSource());   }   public void insert(User user) {     String name = user.getName();     int age = user.getAge().intValue(); //    jdbcTemplate.update("INSERT INTO user (name,age) " //        + "VALUES('" + name + "'," + age + ")");     String sql = "insert into user(name,age) values(?,?)";     getJdbcTemplate().update(sql,new Object[]{name,age});   }   public User find(Integer id) {     List rows = getJdbcTemplate().queryForList(         "SELECT * FROM user WHERE id=" + id.intValue());     Iterator it = rows.iterator();     if (it.hasNext()) {       Map userMap = (Map) it.next();       Integer i = new Integer(userMap.get("id").toString());       String name = userMap.get("name").toString();       Integer age = new Integer(userMap.get("age").toString());       User user = new User();       user.setId(i);       user.setName(name);       user.setAge(age);       return user;     }     return null;   } }

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING/DTD BEAN/EN"     "http://www.springframework.org/dtd/spring-beans.dtd"> <beans>   <bean id="dataSource"      singleton="true">     <property name="driverClassName">       <value>com.mysql.jdbc.Driver</value>     </property>     <property name="url">       <value>jdbc:mysql://localhost:3306/springdb</value>     </property>     <property name="username">       <value>root</value>     </property>     <property name="password">       <value>leizhimin</value>     </property>   </bean>   <bean id="baseDAO" abstract="true">    <property name="dataSource">       <ref bean="dataSource"/>     </property>   </bean>   <bean id="userDAO"      parent="baseDAO">   </bean> </beans>

import org.springframework.context.ApplicationContext; import org.springframework.context.support.FileSystemXmlApplicationContext; /** * Created by IntelliJ IDEA.<br> * <b>User</b>: leizhimin<br> * <b>Date</b>: 2008-4-22 15:59:18<br> * <b>Note</b>: 测试类，客户端 */ public class SpringDAODemo {   public static void main(String[] args) {     ApplicationContext context = new FileSystemXmlApplicationContext("D://_spring//src//com//lavasoft//springnote//ch05_jdbc03_temp//bean-jdbc-temp.xml");     User user = new User();     user.setName("hahhahah");     user.setAge(new Integer(22));     IUserDAO userDAO = (IUserDAO) context.getBean("userDAO");     userDAO.insert(user);     user = userDAO.find(new Integer(1));     System.out.println("name: " + user.getName());   } }

运行结果：

log4j:WARN No appenders could be found for logger (org.springframework.core.CollectionFactory). log4j:WARN Please initialize the log4j system properly. name: jdbctemplate Process finished with exit code 0

Spring DAO之Hibernate

HibernateDaoSupport - Hibernate数据访问对象的基类。 需要一个SessionFactory，同时为子类提供 HibernateTemplate。也可以选择直接通过 提供一个HibernateTemplate来初始化， 这样就可以重用后者的设置，例如SessionFactory， flush模式，异常翻译器（exception translator）等等。

本节主要讨论Sping对HibernateTemplate的支持。

下面是个例子：

drop table if exists user; /*==============================================================*/ /* Table: user                         */ /*==============================================================*/ create table user (   id          bigint AUTO_INCREMENT not null,   name         varchar(24),   age         int,   primary key (id) ); 

/** * Created by IntelliJ IDEA.<br> * <b>Note</b>: Hiberante实体类 */ public class User {   private Integer id;   private String name;   private Integer age;   public Integer getId() {     return id;   }   public void setId(Integer id) {     this.id = id;   }   public String getName() {     return name;   }   public void setName(String name) {     this.name = name;   }   public Integer getAge() {     return age;   }   public void setAge(Integer age) {     this.age = age;   } }

<?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="com.lavasoft.springnote.ch06_hbm_02deTx.User"       table="user">     <id name="id" column="id">       <generator/>     </id>     <property name="name" column="name"/>     <property name="age" column="age"/>   </class> </hibernate-mapping>

/** * Created by IntelliJ IDEA.<br> * <b>User</b>: leizhimin<br> * <b>Date</b>: 2008-4-23 15:37:43<br> * <b>Note</b>: DAO接口 */ public interface IUserDAO {   public void insert(User user);   public User find(Integer id); }  import org.hibernate.SessionFactory; import org.springframework.orm.hibernate3.HibernateTemplate; /** * Created by IntelliJ IDEA.<br> * <b>User</b>: leizhimin<br> * <b>Date</b>: 2008-4-23 15:15:55<br> * <b>Note</b>: DAO实现 */ public class UserDAO implements IUserDAO {   private HibernateTemplate hibernateTemplate;   public void setSessionFactory(SessionFactory sessionFactory) {     this.hibernateTemplate =new HibernateTemplate(sessionFactory);   }   public void insert(User user) {     hibernateTemplate.save(user);     System.out.println("所保存的User对象的ID:"+user.getId());   }   public User find(Integer id) {     User user =(User) hibernateTemplate.get(User.class, id);     return user;   } }

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING/DTD BEAN/EN" "http://www.springframework.org/dtd/spring-beans.dtd"> <beans>   <bean id="dataSource"     >     <property name="driverClassName">       <value>com.mysql.jdbc.Driver</value>     </property>     <property name="url">       <value>jdbc:mysql://localhost:3306/springdb</value>     </property>     <property name="username">       <value>root</value>     </property>     <property name="password">       <value>leizhimin</value>     </property>   </bean>   <bean id="sessionFactory"           destroy-method="close">     <property name="dataSource">       <ref bean="dataSource"/>     </property>     <property name="mappingResources">       <list>         <value>com/lavasoft/springnote/ch06_hbm_02proTx/User.hbm.xml</value>       </list>     </property>     <property name="hibernateProperties">       <props>         <prop key="hibernate.dialect">           org.hibernate.dialect.MySQLDialect         </prop>       </props>     </property>   </bean>   <bean id="userDAO">     <property name="sessionFactory">       <ref bean="sessionFactory"/>     </property>   </bean> </beans>

import org.springframework.context.ApplicationContext; import org.springframework.context.support.FileSystemXmlApplicationContext; /** * Created by IntelliJ IDEA.<br> * <b>Note</b>: 测试类、客户端 */ public class SpringHibernateDemo {   public static void main(String[] args) {     ApplicationContext context =new FileSystemXmlApplicationContext("D://_spring//src//com//lavasoft//springnote//ch06_hbm_02proTx//bean-hbm_tx.xml");     // 建立DAO物件     IUserDAO userDAO = (IUserDAO) context.getBean("userDAO");     User user = new User();     user.setName("caterpillar");     user.setAge(new Integer(30));     userDAO.insert(user);     user = userDAO.find(new Integer(1));     System.out.println("name: " + user.getName());   } }

运行结果：

log4j:WARN No appenders could be found for logger (org.springframework.core.CollectionFactory). log4j:WARN Please initialize the log4j system properly. 所保存的User对象的ID:18 name: jdbctemplate Process finished with exit code 0