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Spring Bean常用注解
@Component：通常注解，可用於任何Bean
@Repository：通常用於注解DAO層，即持久層
@Service：通常用於注解Service層，即服務層
@Controller：通常用於注解Controller層，即控制層
類的自動檢測及Bean的注冊
<context:component-scan base-package=""/>：自動掃描base-package定義的包或其子包下的類，並將帶有@Component,@Controller,@Service,@Repository等注解的類自動注冊到IOC容器中。
<context:annotation-config/>：隱式的向Spring容器中注冊AutowiredAnnotationBeanPostProcessor、CommonAnnotationBeanPostProcessor、PersistenceAnnotationBeanPostProcessor 和RequiredAnnotationBeanPostProcessor 這四個BeanPostProcessor。
<context:component-scan/>包含了<context:annotation-config/>，因此使用<context:component-scan/>就不用再使用<context:annotation-config/>
定義Bean
Bean名稱由BeanNameGenerator生成（@Component,@Controller,@Service,@Repository都有個name屬性用於顯示的指定Bean Name；默認是類名首字母小寫）
也可使用<context:component-scan/>中的name-generator自定義Bean的命名策略，但是要實現BeanNameGenerator接口並且包含一個無參構造器
作用域
@Scope注解標識Bean的作用域。默認是singleton。
實例
1.項目結構
2.pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.spring</groupId>
<artifactId>Spring-BeanAnnotation</artifactId>
<packaging>jar</packaging>
<version>0.0.1-SNAPSHOT</version>
<name>Spring-BeanAnnotation Maven Webapp</name>
<url>http://maven.apache.org</url>
<properties>
<spring.version>4.3.7.RELEASE</spring.version>
</properties>
<dependencies>
<!-- junit依賴 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<!-- spring核心依賴 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
</dependencies>
<build>
<finalName>Spring-BeanAnnotation</finalName>
</build>
</project>
3.spring-beanannotation.xml
<?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.xsd">
<!-- 自動掃描包下的Bean並注冊到IOC容器中 -->
<context:component-scan base-package="org.spring.annotation.bean"/>
</beans>
4.BeanAnnotation.java
package org.spring.annotation.bean;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;
@Scope("prototype")
@Component
public class BeanAnnotation {
public void say() {
System.out.println("注解方式獲取成功");
}
public void hasCode() {
System.out.println("BeanAnnotation:" + this.hashCode());
}
}
5.TestBase.java
package org.spring.annotation.test;
import org.junit.After;
import org.junit.Before;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.util.StringUtils;
public class TestBase {
private ClassPathXmlApplicationContext context;
private String xmlPath;
/**
* 無參構造器
*/
public TestBase() {
}
/**
* 含參構造器，初始化配置文件路徑
*
* @param xmlPath
* 配置文件路徑
*/
public TestBase(String xmlPath) {
this.xmlPath = xmlPath;
}
/**
* 初始化spring的IOC容器
*/
@Before
public void before() {
if(StringUtils.isEmpty(xmlPath)) {//配置文件默認路徑
xmlPath = "classpath:spring-*.xml";
}
//加載配置文件到spring容器中
context = new ClassPathXmlApplicationContext(xmlPath.split("[,\\s]+"));
//啟動IOC容器s
context.start();
}
/**
* 銷毀容器
*/
@After
public void after() {
if(context != null){
context.destroy();
}
}
/**
* 根據bean id獲取bean對象
*/
public Object getBean(String id) {
return context.getBean(id);
}
}
6.TestBeanAnnotation.java
package org.spring.annotation.test;
import org.junit.Test;
import org.spring.annotation.bean.BeanAnnotation;
public class TestBeanAnnotation extends TestBase {
/**
* 構造器傳入spring配置文件路徑
*/
public TestBeanAnnotation() {
super("classpath:spring-beanannotation.xml");
}
/**
* 測試注解方式獲取bean對象
*/
@Test
public void testBeanAnnotation() {
BeanAnnotation bean = (BeanAnnotation) super.getBean("beanAnnotation");
bean.say();
}
/**
* 測試注解方式的Bean的作用域
*/
@Test
public void testBeanScope() {
BeanAnnotation bean = (BeanAnnotation) super.getBean("beanAnnotation");
bean.hasCode();
BeanAnnotation bean2 = (BeanAnnotation) super.getBean("beanAnnotation");
bean2.hasCode();
}
}
7.效果預覽
