Spring系列（二）：Bean注解用法介绍

今天给大家介绍一下Spring中Bean注解的用法,后续的文章给大家介绍Sping其他注解用法，希望对大家日常工作能有所帮助！

1、首先创建一个maven项目引入spring依赖

<dependencies>
    <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.3.9</version>
    </dependency>
</dependencies>

2、新建一个person.java 实体类

package com.spring.bean;


public class Person {
    private String name;
    private Integer age;
    private String address;


    public Person(String name, Integer age, String address) {
        this.name = name;
        this.age = age;
        this.address = address;
    }


    public Person() {
    }


    public String getName() {
        return name;
    }


    public void setName(String name) {
        this.name = name;
    }


    public Integer getAge() {
        return age;
    }


    public void setAge(Integer age) {
        this.age = age;
    }


    public String getAddress() {
        return address;
    }


    public void setAddress(String address) {
        this.address = address;
    }


    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age='" + age + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

3、新建配置类 TestBeanConfig.java

package com.spring.config;


import com.spring.bean.Person;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;


@Configuration
public class TestBeanConfig {
    /*@Bean作用是注册一个Bean，类型为返回值的类型，默认是使用方法名作为id，可以自己定义
     * value 可以自定义id，默认和方法名一致
     * */
    @Bean(value = "person1")
    public Person person() {
        return new Person("小王", 35, "北京");
    }
}

4、resources 创建配置文件

<?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 https://www.springframework.org/schema/context/spring-context.xsd">
    <context:component-scan base-package="java"></context:component-scan>
    <bean id="person" class="com.spring.bean.Person">
        <property name="name" value="小明"></property>
        <property name="age" value="30"></property>
        <property name="address" value="苏州"></property>
    </bean>
</beans>

5、新建测试类TestBean.java 具体展示注解方式和配置方式的示例

package com.spring.test;


import com.spring.bean.Person;
import com.spring.config.TestBeanConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;


public class TestBean {
    public static void main(String[] args) {
        //配置文件方式
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("person.xml");
        Person bean = (Person) applicationContext.getBean("person");
        System.out.println("配置方式:");
        System.out.println(bean);
        // 注解方式 AnnotationConfigApplicationContext 注解的方式获取spring容器
        AnnotationConfigApplicationContext annotationContext = new AnnotationConfigApplicationContext(TestBeanConfig.class);
        Person annotationPerson = (Person) annotationContext.getBean("person1");
        System.out.println("注解方式:");
        System.out.println(annotationPerson);
        // 用来获取Spring容器中指定类型的所有JavaBean的名称
        String[] beanNamesForType = annotationContext.getBeanNamesForType(Person.class);
        for (String item : beanNamesForType) {
            System.out.println(item);
        }
    }


}

6、运行效果：