spring1

spring容器重要的特性就是IOC(控制反转)和DI(依赖注入)
控制反转：解决对象创建的问题；即对象创建交给了容器
依赖注入：在创建对象后，对象关系的处理就是依赖注入；或者组件之间的关系通过容器自动装配(依赖注入)

导入依赖

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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.dwb.spring</groupId>
  <artifactId>dwb-spring</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>dwb-spring</name>
  <url>http://maven.apache.org</url>
  
  <dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.3.12.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
  </dependencies>

</project>

配置类

@Configuration  //告诉Spring 这是一个配置类
public class MainConfig {
    //给容器注册一个Bean;类型为返回值的类型，id默认是用方法名
    @Bean("person")
    public Person person01() {
        return new Person("lisi", 20);
    }
}

测试类

ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
        Person bean = applicationContext.getBean(Person.class);
        System.out.println(bean);
        
        String[] beanNamesForType = applicationContext.getBeanNamesForType(Person.class);
        for (String name : beanNamesForType) {
            System.out.println(name);
        }```