Spring2学习笔记(2)-使用数据库

最新推荐文章于 2024-08-08 19:26:18 发布

rollice

最新推荐文章于 2024-08-08 19:26:18 发布

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分类专栏： Java 文章标签： spring hibernate annotations bean jdbc dao

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1 使用数据库

1.1 配置数据源

1.1.1 JNDI 数据源

< bean id = "dataSource"

class = "org.springframework.jndi.JndiObjectFactoryBean" scope = "singleton" >

< property name = "jndiName" value = "/jdbc/RantzDatasource" />

< property name = "resourceRef" value = "true" />

</ bean >

resourceRef ：当为 true 的时候， jndiName 会被添加 java:comp/env/

Spring2.0 里使用 jee 命名空间里的配置

< jee:jndi-lookup id = "dataSource"

jndi-name = "/jdbc/RantzDatasource"

resource-ref = "true" />

1.1.2 基于 JDBC 驱动的数据源

< bean id = "dataSource"

class = "org.springframework.jdbc.datasource.DriverManagerDataSource" >

< property name = "driverClassName"

value = " oracle.jdbc.driver.OracleDriver " />

< property name = "url"

value = " jdbc:oracle:thin:@192.168.1.1:1521:test " />

< property name = "username" value = "zrl" />

< property name = "password" value = "" />

</ bean >

1.1.3 使用数据源连接池

类似 JDBC 驱动，使用 org.apache.commons.dbcp.BasicDataSource 类驱动

1.2 使用 JDBC

1.2.1 使用 JDBC 模板

编写基于 JDBC 的 DAO 涉及配置 JDBC 模板 Bean 、把它装配到 DAO 类、然后使用这个模板访问数据库，这个过程要配置 3 个 Bean ：一个数据源、一个模板、一个 DAO

JdbcTemplate ：最基本的 JDBC 模板，利用 JDBC 和简单的索引参数对数据库的简单访问

NamedParameterJdbcTemplate ：能够在执行查询时把值绑定到 SQL 里的命名参数，而不是使用索引参数

SimpleJdbcTemplate ：选用 java5 的特性，来简化 JDBC 模板的使用

1.2.1.1 JdbcTemplate

1) XML 配置

< bean id = "jdbcTemplate"

class = "org.springframework.jdbc.core.JdbcTemplate" >

< property name = "dataSource" ref = "dataSource" />

</ bean >

2) 把 JdbcTemplate 装配到 DAO

public class JdbcRantDao implements RantDao {

...

private JdbcTemplate jdbcTemplate ;

public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {

this . jdbcTemplate =jdbcTemplate;

}

3) 设置 JdbcRantDao 的 jdbcTemplate 属性

< bean id = "rantDao" class = "com.roadrantz.dao.jdbc.JdbcRantDao" >

< property name = "jdbcTemplate" ref = "jdbcTemplate" />

</ bean >

4) 使用保存

private static final String MOTORIST_INSERT = "insert into motorist (id, email, password, firstName, lastName) "

+ "values (null, ?,?,?,?)" ;

public void saveMotorist(Motorist motorist) {

jdbcTemplate .update(

MOTORIST_INSERT ,

new Object[] { motorist.getEmail(),

motorist.getPassword(), motorist.getFirstName(),

motorist.getLastName() });

}

5) 使用查询

private static final String MOTORIST_SELECT = "select id, email, password, firstName, lastName from motorist" ;

private static final String MOTORIST_BY_ID_SELECT = MOTORIST_SELECT

+ " where id=?" ;

public Motorist getMotoristById ( long id) {

List matches = jdbcTemplate .query( MOTORIST_BY_ID_SELECT ,

new Object[] { Long.valueOf (id) }, new RowMapper() {

public Object mapRow(ResultSet rs, int rowNum)

throws SQLException,

DataAccessException {

Motorist motorist = new Motorist();

motorist.setId(rs.getInt(1));

motorist.setEmail(rs.getString(2));

motorist.setPassword(rs.getString(3));

motorist.setFirstName(rs.getString(4));

motorist.setLastName(rs.getString(5));

return motorist;

}

});

return matches.size() > 0 ? (Motorist) matches.get(0) : null ;

}

1.2.1.2 NamedParameterJdbcTemplate

使用方法及步骤同 jdbcTemplate

命名参数：

private static final String MOTORIST_INSERT = "insert into motorist (id, email, password, firstName, lastName) "

+ "values (null, :email, :password, :firstName, :lastName)" ;

使用保存

public void saveMotorist (Motorist motorist) {

Map<String, String> parameters = new HashMap<String, String>();

parameters.put( "email" , motorist.getEmail());

parameters.put( "password" , motorist.getPassword());

parameters.put( "firstName" , motorist.getFirstName());

parameters.put( "lastName" , motorist.getLastName());

jdbcTemplate .update( MOTORIST_INSERT , parameters);

}

1.2.1.3 SimpleJdbcTemplate

使用方法及步骤同 jdbcTemplate

查询

public Motorist getMotoristById ( long id) {

List<Motorist> matches = jdbcTemplate .query(

MOTORIST_BY_ID_SELECT ,

new ParameterizedRowMapper<Motorist>() {

public Motorist mapRow(ResultSet rs, int rowNum)

throws SQLException {

Motorist motorist = new Motorist();

motorist.setId(rs.getInt(1));

motorist.setEmail(rs.getString(2));

motorist.setPassword(rs.getString(3));

motorist.setFirstName(rs.getString(4));

motorist.setLastName(rs.getString(5));

return motorist;

}

}, id);

return matches.size() > 0 ? matches.get(0) : null ;

}

1.2.2 使用 Spring 对 JDBC 的 DAO 支持类

DAO 类继承 JdbcDaoSupport

public class JdbcRantDao extends JdbcDaoSupport implements RantDao

只需配置 jdbcTemplate 或 dataSource

< bean id = "rantDao" class = "com.roadrantz.dao.jdbc.JdbcRantDao" >

< property name = "dataSource" ref = "dataSource" />

</ bean >

< bean id = "rantDao" class = "com.roadrantz.dao.jdbc.JdbcRantDao" >

< property name = "jdbcTemplate " ref = "jdbcTemplate " />

</ bean >

使用 getJdbcTemplate().update

NamedParameterJdbcDaoSupport 、 SimpleJdbcDaoSupport 的使用方法类似

1.3 在 Spring 里集成 Hibernate

1.3.1 使用 Hibernate 模板

1) 配置 HibernateTemplate

< bean id = "hibernateTemplate"

class = "org .springframework .orm .hibernate3.HibernateTemplate" >

< property name = "sessionFactory" ref = "sessionFactory" />

</ bean >

2) 配置 sessionFactory

使用典型的 Hibernate 映射文件

< bean id = "sessionFactory"

class = "org .springframework .orm .hibernate3.LocalSessionFactoryBean" >

< property name = "dataSource" ref = "dataSource" />

< property name = "mappingResources" >

< list >

< value > com /roadrantz /domain/Rant.hbm .xml </ value >

< value > com /roadrantz /domain/Motorist.hbm .xml </ value >

< value > com /roadrantz /domain/Vehicle.hbm .xml </ value >

</ list >

</ property >

< property name = "hibernateProperties" >

< props >

< prop key = "hibernate .dialect" > ${hibernate .dialect} </ prop >

</ props >

</ property >

</ bean >

Java5 也可以使用被注解的域对象（这里不做说明）

3) 通过 Hibernate 模板访问数据

public class HibernateRantDao implements RantDao {

...

private Hibernate Template hibernate Template;

public void setTemplate( Hibernate Template template) {

this .hibernate Template =template;

}

4) Spring 里配置 DAO

< bean id = "rantDao" class = "com.roadrantz.dao.hibernate.HibernateRantDao" >

< property name = "hibernateTemplate" ref = "hibernateTemplate" />

</ bean >

5) 使用

public Vehicle findVehicleByPlate(String state, String plateNumber) {

List results = getHibernateTemplate()

.find( "from " + VEHICLE + " where state = ? and plateNumber = ?" ,

new Object[] { state, plateNumber });

if (results.size() > 0) {

return (Vehicle) results.get(0);

}

return null ;

}

public Motorist getDriverById (Integer id) {

return (Motorist) getHibernateTemplate().load(Motorist. class , id);

}

1.3.2 建立基于 Hibernate 的 DAO

1) 继承 HibernateDaoSupport

public class HibernateRantDao extends HibernateDaoSupport implements RantDao

2) 数据访问方法使用 getHibernateTemplate()

3) 修改 spring 配置的 Dao

< bean id = "rantDao" class = "com.roadrantz.dao.hibernate.HibernateRantDao" >

< property name = "sessionFactory" ref = "sessionFactory" />

</ bean >

1.3.3 使用 Hibernate3 上下文会话

HibernateTemplate 的缺点是具有一定的侵入性。使用上下文把 DAO 实现与 Spring 解耦，缺点是它们抛出 Hibernate 特有的异常

1) 定义 session

public class HibernateContextualSessionsRantDao implements RantDao {

...

private SessionFactory sessionFactory ;

public void setSessionFactory(SessionFactory sessionFactory) {

this . sessionFactory = sessionFactory;

}

2) Spring 里配置的 DAO 同上

3) 访问

public void saveRant (Rant rant) {

sessionFactory .getCurrentSession() .saveOrUpdate(rant);

}

1.4 缓存

Spring Modules 会提供一个代理来拦截方法并把结果保存到缓存，它并没有提供一个实际的缓存解决方案，而是要依赖于第三方的缓存方案。这里选择 EHCache 。

1.4.1 配置缓存方案

< beans xmlns = "http://www.springframework.org/schema/beans"

xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"

xmlns:ehcache = "http://www.springmodules.org/schema/ehcache"

xsi:schemaLocation = "http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-2.0.xsd

http://www.springmodules.org/schema/ehcache

http://www.springmodules.org/schema/cache/springmodules-ehcache.xsd" >

< ehcache:config

configLocation = "classpath:ehcache.xml" />

< ehcache:annotations >

< ehcache:caching id = "rantzCacheModel" cacheName = "rantzCache" />

</ ehcache:annotations >

</ beans >

EHCache.xml 文件内容

< ehcache >

< defaultCache

maxElementsInMemory = "500"

eternal = "true"

overflowToDisk = "false"

memoryStoreEvictionPolicy = "LFU" />

< cache name = "rantzCache"

maxElementsInMemory = "500"

eternal = "true"

overflowToDisk = "false"

memoryStoreEvictionPolicy = "LFU" />

</ ehcache >

<defaultCache> 是必须有的， <cache> 定义了另一个缓存

memoryStoreEvictionPolicy 当达到最大时的驱逐策略：最近使用 (LRU) 、先入先出 (FIFO) 、较入使用 (LFU)

1.4.2 缓存的代理 Bean

< ehcache:proxy id = "rantDao"

refId = "rantDaoTarget" >

< ehcache:caching

methodName = "getRantsForDay"

cacheName = "rantzCache" />

< echache:flushing

methodName = "saveRant"

cacheName = "rantzCache"

when = "before" />

</ ehcache:proxy >

< ehcache:caching> 元素声明哪个方法要被拦截、其返回要保存到哪个缓存

< echache:flushing> 元素声明了会清空缓存的方法

1.4.3 注解驱动的缓存

@Cacheable ：声明一个方法的返回值应该被缓存

@CacheFlush ：声明一个方法是清空缓存的触发器

@CacheFlush (modelId= "rantzCacheModel" )

public void saveRant(Rant rant);

@Cacheable (modelId= "rantzCacheModel" )

public List<Rant> getAllRants();

在 xml 中配置

< ehcache:annotations >

< ehcache:caching id = "rantzCacheModel" cacheName = "rantzCache" />

< ehcache:caching id = "rantzFlushModel" cacheName = "rantzCache" when = "before" />

</ ehcache:annotations >

1.5 事务管理

ACID ：原子性（ Atomic ）、一致性（ Consistent ）、隔离性（ Isolated ）、持久性（ Durable ）

1.5.1 事务管理器

1.5.1.1 JDBC 事务

< bean id = "transactionManager"

class = "org.springframework.jdbc.datasource.DataSourceTransactionManager " >

< property name = "dataSource" ref = "dataSource" />

</ bean >

1.5.1.2 Hibernate 事务

< bean id = "transactionManager"

class = "org.springframework.orm.hibernate3.HibernateTransactionManager " >

< property name = "sessionFactory" ref = "sessionFactory" />

</ bean >

1.5.2 在 Spring 中编写事物

略

1.5.3 声明式事务

public class RantServiceImpl implements RantService {

public void addRant(Rant rant) {

rant.setPostedDate( new Date());

Vehicle rantVehicle = rant.getVehicle();

Vehicle existingVehicle = rantDao .findVehicleByPlate(rantVehicle

.getState(), rantVehicle.getPlateNumber());

if (existingVehicle != null ) {

rant.setVehicle(existingVehicle);

} else {

rantDao .saveVehicle(rantVehicle);

}

rantDao .saveRant(rant);

}

1.5.3.1 代理事务

< bean id = "rantService" class = "org.springframework.transaction.interceptor.TransactionProxyFactoryBean" >

< property name = "target" ref = "rantServiceTarget" /> // 装配事务目标

< property name = "proxyInterfaces" value = "com.roadrantz.service.RantService" /> // 指定代理接口

< property name = "transactionManager" ref = "transactionManager" /> // 装配事务管理器

< property name = "transactionAttributes" > // 装配事务规则、边界

< props >

< prop key = "add*" > PROPAGATION_REQUIRED </ prop >

< prop key = "*" > PROPAGATION_SUPPORTS,readOnly </ prop >

</ props >

</ property >

</ bean >

PROPAGATION_REQUIRED: 表示此方法必须在一个事务中运行

PROPAGATION_SUPPORTS ：表示当前方法不需要事务性上下文。

1.5.3.2 创建一个事务代理模板

父 Bean

< bean id = "txProxyTemplate" class = "org.springframework.transaction.interceptor.TransactionProxyFactoryBean" abstract=”true” >

< property name = "transactionManager" ref = "transactionManager" /> // 装配事务管理器

< property name = "transactionAttributes" > // 装配事务规则、边界

< props >

< prop key = "add*" > PROPAGATION_REQUIRED </ prop >

< prop key = "*" > PROPAGATION_SUPPORTS,readOnly </ prop >

</ props >

</ property >

</ bean >

子 Bean

< bean id = "rantService" parent="txProxyTemplate" >

< property name = "target" ref = "rantServiceTarget" />

< property name = "proxyInterfaces" value = "com.roadrantz.service.RantService" />

</ bean >

1.5.3.3 在 Spring2.0 里声明事务

增加 tx 名称空间

xmlns:tx = "http://www.springframework.org/schema/tx"

xsi:schemaLocation = "...

http://www.springframework.org/schema/tx

http://www.springframework.org/schema/tx/spring-tx-2.0.xsd" >

配置通知

< tx:advice id = "txAdvice" transaction-manager = "transactionManager" >

< tx:attributes >

< tx:method name = "add*" propagation = "REQUIRED" />

< tx:method name = "*" propagation = "REQUIRED" read-only = "true" />

</ tx:attributes >

</ tx:advice >

通知器

< aop:config >

< aop:advisor advice-ref = "txAdvice"

pointcut = "execution(* *..RantService.*(..))" />

</ aop:config >

表示通知 RantService 接口的所有方法

1.5.3.4 注释驱动事务

@Transactional (propagation = Propagation. SUPPORTS , readOnly = true )

public interface RantService {

@Transactional (propagation = Propagation. REQUIRED )

public void addRant(Rant rant);

...

}

只需在 XML 上加上以下配置代码

< tx:annotation-driven transaction-manager = "transactionManager" />