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上海网站建设推,企业seo顾问,唐山app开发公司,南京网站设计建设推荐Spring针对Bean管理中创建对象提供的注解有哪些？Component：普通Service：业务逻辑层Controller：controller层Repository：dao层用注解的方式是为什么？简化xml方式开发，只需要注解就可以完成在配置…

Spring针对Bean管理中创建对象提供的注解有哪些？

@Component：普通

@Service：业务逻辑层

@Controller：controller层

@Repository：dao层

用注解的方式是为什么？

简化xml方式开发，只需要注解就可以完成在配置文件中的配置

如何实现注解开发？

创建对象

组件扫描

package com.atguigu.spring5.ComponentScan;import org.springframework.stereotype.Component;/*** @BelongsProject: 02-Spring* @BelongsPackage: com.atguigu.spring5* @Author: dengLiMei* @CreateTime: 2023-02-04  16:56* @Description: TODO* @Version: 1.0*/
//value可以不写，如果不写默认是类名的首字母小写
@Component(value = "user")
public class User {public void add() {System.out.println("aaaa");}
}

package com.atguigu.spring5.ComponentScan;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;/*** @BelongsProject: 02-Spring* @BelongsPackage: com.atguigu.spring5.ComponentScan* @Author: dengLiMei* @CreateTime: 2023-02-10  15:12* @Description: TODO* @Version: 1.0*/
public class Main {public static void main(String[] args) {ApplicationContext content= new ClassPathXmlApplicationContext("beans.xml");User user = content.getBean("user", User.class);user.add();}
}

<?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:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"><!--    开启组件扫描如果扫描多个包，多个包使用逗号隔开扫描包上层目录--><!--   表示： 扫描包中的所有类--><context:component-scan base-package="com.atguigu.spring5"></context:component-scan><!--    use-default-filters=“false”：表示现在不使用默认filter，自己配置filtercontext：include-filter，设置扫描哪些内容--><!--    表示：  只扫描注解带Controller的类--><context:component-scan base-package="com.atguigu.spring5" use-default-filters="false"><context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/></context:component-scan><!--    下面配置扫描包所有内容context：include-filter，设置扫描哪些内容--><!--    表示：  除了Controller其余类都扫描--><context:component-scan base-package="com.atguigu.spring5"><context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>-filtertype="" expression=""/></context:component-scan>
</beans>

属性注入

@Autowired：根据类型注入

@Qualifier：根据名称进行注入，和Autowired

@Resource：可以根据类型或名称注入

@Value：普通属性注入

javax：java扩展包

完全注解开发

Configuration：作为配置类，替代xml配置文件

package com.atguigu.spring5.SpringConfiguration;import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;@Configuration
@ComponentScan(basePackages = {"com.atguigu.spring5"})
public class SpringConfigure {}

package com.atguigu.spring5.ScopeTest;import org.springframework.stereotype.Component;/*** @BelongsProject: 02-Spring* @BelongsPackage: com.atguigu.spring5.Book* @Author: dengLiMei* @CreateTime: 2023-02-08  19:28* @Description: TODO* @Version: 1.0*/
@Component
public class Book {private String bname;private String bauthor;public void setBname(String bname) {this.bname = bname;}public void setBauthor(String bauthor) {this.bauthor = bauthor;}public static void main(String[] args) {Book book = new Book();book.setBname("abc");}public void testDemo() {System.out.println(bname + "---" + "aaa");}}

package com.atguigu.spring5.SpringConfiguration;import com.atguigu.spring5.ScopeTest.Book;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;/*** @BelongsProject: 02-Spring* @BelongsPackage: com.atguigu.spring5.SpringConfiguration* @Author: dengLiMei* @CreateTime: 2023-02-11  09:38* @Description: TODO* @Version: 1.0*/
public class Main {public static void main(String[] args) {
//        加载配置类ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfigure.class);
//        创建实例Book book = context.getBean("book", Book.class);
//        调用方法book.testDemo();}
}

输出结果：