我在 Spring 应用程序中使用 xml 配置。现在我想将现有的类转换为使用注释(如 @service、@Repository 等)而不是 xml 配置。
业务逻辑(与此问题无关，仅用于理解): 服务连接到美洲数据库并查找 sku(产品)并停用 sku。 服务连接到 EMEA 数据库并查找 sku(产品)并停用 sku。
这是示例代码。
/* Service code, which has 2 instances of SkuDAO, one connecting to US database and one connecting to EMEA database */
public class DeactivationService {
private static final Logger LOG = Logger.getLogger(DeactivationService.class);
private SkuDAO amerdao; //Dependency Injection Amer
private SkuDAO emeadao; //Dependency Injection EMEA
public DeactivationService(SkuDAO amerdao,SkuDAO emeadao) {
this.amerdao=amerdao;
this.emeadao=emeadao;
}
/*
* Step 1: find inactive sku in americas skudao1.find()
* Step 2: find inactive sku in emea skudao2.find()
* Step 3: deactivate sku in americas
* Step 4: deactivate sku in emea
*/
public void deactivateSku() {
List<Sku> totalList = new ArrayList<Sku>();
List<Sku> amerList = amerdao.find();
List<Sku> emeaList = emeadao.find();
amerdao.deactivate(amerList);
emeaList.deactivate(emeaList);
}
}
/* DAO interface */
public interface SkuDAO {
public List<Sku> find();
public void deactivate(List<Sku>);
}
/* DAO Implementation
Here one constructor in which DataSource is injected
*/
public class SkuDAOImpl implements SkuDAO {
private DataSource datasource; //Dependency injection
private JdbcTemplate jdbcTemplate;
public SkuDAOImpl(DataSource datasource) {
this.datasource=datasource;
}
public List<Sku> find() {
//some processing to find the sku, purposely left empty as it is a sample code
}
public void deactivate(List<Sku>) {
//some processing to deactivate the sku, purposely left empty as it is a sample code
}
}
Spring 配置:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<context:property-placeholder location="file:${dbconfiguration}"/>
<bean id="AmericasDataSource" class="dell.harmony.data.HarmonyBasicDataSource" destroy-method="close" >
<property name="url"><value>${HarmonyAmericasDb.url}</value></property>
<property name="driverClassName"><value>${HarmonyAmericasDb.driverClassName}</value></property>
<property name="username"><value>${HarmonyAmericasDb.username}</value></property>
<property name="password"><value>${HarmonyAmericasDb.password}</value></property>
<property name="initialSize"><value>${HarmonyAmericasDb.initialSize}</value></property>
<property name="maxActive"><value>${HarmonyAmericasDb.maxActive}</value></property>
<property name="maxWait"><value>${HarmonyAmericasDb.maxWait}</value></property>
<property name="maxIdle"><value>${HarmonyAmericasDb.maxIdle}</value></property>
<property name="minIdle"><value>${HarmonyAmericasDb.minIdle}</value></property>
<property name="removeAbandoned"><value>${HarmonyAmericasDb.removeAbandoned}</value></property>
<property name="removeAbandonedTimeout"><value>${HarmonyAmericasDb.removeAbandonedTimeout}</value></property>
</bean>
<bean id="EMEADataSource" class="dell.harmony.data.HarmonyBasicDataSource" destroy-method="close" >
<property name="url"><value>${HarmonyEMEADb.url}</value></property>
<property name="driverClassName"><value>${HarmonyEMEADb.driverClassName}</value></property>
<property name="username"><value>${HarmonyEMEADb.username}</value></property>
<property name="password"><value>${HarmonyEMEADb.password}</value></property>
<property name="initialSize"><value>${HarmonyEMEADb.initialSize}</value></property>
<property name="maxActive"><value>${HarmonyEMEADb.maxActive}</value></property>
<property name="maxWait"><value>${HarmonyEMEADb.maxWait}</value></property>
<property name="maxIdle"><value>${HarmonyEMEADb.maxIdle}</value></property>
<property name="minIdle"><value>${HarmonyEMEADb.minIdle}</value></property>
<property name="removeAbandoned"><value>${HarmonyEMEADb.removeAbandoned}</value></property>
<property name="removeAbandonedTimeout"><value>${HarmonyEMEADb.removeAbandonedTimeout}</value></property>
</bean>
**<!-- Sku Deactivation -->**
<bean id="SkuAmerDao" class="dell.harmony.service.skudeactivation.dao.SkuDAOImpl">
<constructor-arg index="0"><ref bean="AmericasDataSource"/></constructor-arg>
</bean>
<bean id="SkuEMEADao" class="dell.harmony.service.skudeactivation.dao.SkuDAOImpl">
<constructor-arg index="0"><ref bean="EMEADataSource"/></constructor-arg>
</bean>
<bean id="ServiceManager" class="dell.harmony.service.skudeactivation.service.DeactivationService">
<constructor-arg index="0"><ref bean="SkuAmerDao"/></constructor-arg>
<constructor-arg index="1"><ref bean="SkuEMEADao"/></constructor-arg>
</bean>
</beans>
现在我想将上述类转换为在 xml("Sku Deactivation") 内突出显示的类，并进行注释。
我的转换代码如下:
@Service
public class DeactivationService {
private static final Logger LOG = Logger.getLogger(DeactivationService.class);
private SkuDAO amerdao; //Dependency Injection Amer
private SkuDAO emeadao; //Dependency Injection EMEA
@Autowired(required=true)
public DeactivationService( @Qualifier("SkuAmerDao") SkuDAO amerdao, @Qualifier("SkuEMEADao") SkuDAO emeadao) {
this.amerdao=amerdao;
this.emeadao=emeadao;
}
}
在上面的构造函数中，现在'amerdao'实例应该注入(inject)AmericasDataSource，'emeadao'则注入(inject)EMEADataSource，如何做到这一点？
请注意，我在 SkuDAOImpl 中没有 setter 。另外，SkuDAOImpl 内部只有一个数据源实例。
- 您能否给出带注释的 SkuDAOImpl 示例代码。
- 任何建议，以改进从 service 到 dao 的编码，如果可以以更好的方式完成的话。 (不需要回答这个问题)
现在已编辑:为了澄清问题 1，我想删除 Spring xml 中的以下两行并使用注释代替我的 DeactivationService。可能吗？
<bean id="SkuAmerDao" class="dell.harmony.service.skudeactivation.dao.SkuDAOImpl">
<constructor-arg index="0"><ref bean="AmericasDataSource"/></constructor-arg>
</bean>
<bean id="SkuEMEADao" class="dell.harmony.service.skudeactivation.dao.SkuDAOImpl">
<constructor-arg index="0"><ref bean="EMEADataSource"/></constructor-arg>
</bean>
最佳答案
关于:
@Service
public class DeactivationService {
private static final Logger LOG = Logger.getLogger(DeactivationService.class);
@Autowired
@Qualifier("SkuAmerDao")
private SkuDAO amerdao; //Dependency Injection Amer
@Autowired
@Qualifier("SkuEMEADao")
private SkuDAO emeadao; //Dependency Injection EMEA
// no constructor needed.
}
public abstract class BaseDao implements SkuDAO {
private final JdbcTemplate jdbcTemplate;
protected BaseDao() {
this.jdbcTemplate = new JdbcTemplate(getDataSource());
}
protected abstract DataSource getDataSource();
public List<Sku> find() {
//some processing to find the sku, purposely left empty as it is a sample code
}
public void deactivate(List<Sku>) {
//some processing to deactivate the sku, purposely left empty as it is a sample code
}
}
@Repository("SkuAmerDao")
public class SkuAmerDAOImpl extends BaseDao {
@Autowired
@Qualifier("AmericasDataSource")
private DataSource datasource; //Dependency injection
@Override
protected DataSource getDatasource() {
return dataSource;
}
}
@Repository("SkuEMEADao")
public class SkuEMEADAOImpl extends BaseDao {
@Autowired
@Qualifier("EMEADataSource")
private DataSource datasource; //Dependency injection
@Override
protected DataSource getDatasource() {
return dataSource;
}
}
始终相同的原则:
- class 通过注解
@Service、@Component、@Repository成为一个 bean(这些注解可以采用 bean 的名称)作为值) - 依赖注入(inject)是在带有
@Autowired的字段上进行的，如果有多个相应的bean(在您的情况下，您有两个DataSource)，请添加一个@Qualifier来指定哪个。
完整文档 here .
关于java - Spring注解: Converting XML Configuration to Annotation，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20697183/