Spring學習總結5(IOC-基于注解Annotation)

要使用Annotation，需确認Spring的版本是2.0以上，JDK版本是5.0以上

使用注解的XML的配置

<?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-2.5.xsd

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

http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<!-- 指明Spring容器使用注解的方式初始化bean -->

<context:annotation-config/>

</beans>

@Autowired

按類型去查找并注入

使用範圍：

1.setter方法

public class SimpleMovieLister {

private MovieFinder movieFinder;

@Autowired

public void setMovieFinder(MovieFinder movieFinder) {

this.movieFinder = movieFinder;

}

// ...

}

2.以成員變量(bean)為參數的方法

public class MovieRecommender {

private MovieCatalog movieCatalog;

private CustomerPreferenceDao customerPreferenceDao;

@Autowired

public void prepare(MovieCatalog movieCatalog, CustomerPreferenceDao customerPreferenceDao) {

this.movieCatalog = movieCatalog;

this.customerPreferenceDao = customerPreferenceDao;

}

// ...

}

3.構造方法或成員變量

public class MovieRecommender {

@Autowired

private MovieCatalog movieCatalog;

private CustomerPreferenceDao customerPreferenceDao;

@Autowired

public MovieRecommender(CustomerPreferenceDao customerPreferenceDao) {

this.customerPreferenceDao = customerPreferenceDao;

}

// ...

}

@Autowired(required=false) 當查找失敗時不會報錯，預設不寫時為required=true

@Qualifier

按名字去查找并注入

1.使用在成員變量上

public class MovieRecommender {

@Autowired

@Qualifier("mainCatalog")

private MovieCatalog movieCatalog;

// ...

}

2.使用在方法參數bean上

public class MovieRecommender {

private MovieCatalog movieCatalog;

private CustomerPreferenceDao customerPreferenceDao;

@Autowired

public void prepare(@Qualifier("mainCatalog") MovieCatalog movieCatalog, CustomerPreferenceDao customerPreferenceDao) {

this.movieCatalog = movieCatalog;

this.customerPreferenceDao = customerPreferenceDao;

}

// ...

}

@Resource

按name值進行查找   @Resource有一個‘name’屬性，預設時，Spring 将這個值解釋為要注射的 bean 的名字

public class SimpleMovieLister {

private MovieFinder movieFinder;

@Resource(name="myMovieFinder")

public void setMovieFinder(MovieFinder movieFinder) {

this.movieFinder = movieFinder;

}

}

// 在容器中查找名字為myMovieFinder的bean

public class SimpleMovieLister {

private MovieFinder movieFinder;

@Resource

public void setMovieFinder(MovieFinder movieFinder) {

this.movieFinder = movieFinder;

}

}

// 在容器中查找名字為movieFinder的bean

@Component

是所有受Spring管理元件的通用形式。

@Repository(存儲層)、@Service(服務層)和 @Controller(控制層)則是@Component的細化， 用來表示更具體的用例(例如，分别對應了持久化層、服務層和表現層)。也就是說， 你能用@Component來注解你的元件類， 但如果用@Repository、@Service 或@Controller來注解它們，你的類也許能更好地被工具處理，或與切面進行關聯。

加上該注解的bean，就不用在xml中進行bean的定義了。

xml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-2.5.xsd

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

http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<context:component-scan base-package="org.example"/>

</beans>

使用@Component注解需要在xml配置自動掃描範圍。同時Spring也提供了在掃描範圍内進行過濾的配置。

過濾器類型	表達式範例
annotation	org.example.SomeAnnotation
assignable	org.example.SomeClass
regex	org/.example/.Default.*
aspectj	org.example..*Service+

<context:component-scan base-package="org.example">

<!-- 配置包含過濾 -->

<context:include-filter type="regex" expression=".*Stub.*Repository"/>

<!-- 配置排除過濾 -->

<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>

</context:component-scan>

// 注冊名字為myMovieLister，類型為SimpleMovieLister,生命周期為prototype的bean

@Component("myMovieLister")

@Scope("prototype")

public class SimpleMovieLister {

// ...

}

// 注冊名字為movieFinderImpl ，類型為SimpleMovieLister的bean (預設bean名字為類名且首字母小寫，生命周期為singleton)

@Component

public class MovieFinderImpl implements MovieFinder {

// ...

}

@PostConstruct

表明該方法在bean初始化時首先執行

@PostConstruct

public void init() {

System.out.println("init");

}

@PreDestroy

表明該方法在bean生命周期結束時執行

@PreDestroy

public void destroy() {

System.out.println("destroy");

}