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.xsd http://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filter context：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"/>-filter type="" 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：
