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:
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