@bean&@configuration

使用xml配置文件注入bean

1、建立实体类

package com.leven.bean;

public class Person {
    private String name;
    private int age;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

    public Person() {
        super();
    }


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

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

2、建立xml文件,注入bean。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean class="com.leven.bean.Person" id="person">
        <property name="age" value="1"></property>
        <property name="name" value="leven"></property>
    </bean>
</beans>

3、建立主程序入口，获取容器中的person。

package com.leven.main;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainTest {
    public static void main(String[] args) {

        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
        Object person = applicationContext.getBean("person");
        System.out.println(person);
    }
}

4、结果

Person{name='leven', age=1}

2.2、使用注解的方式注入bean

1、创建配置类

package com.leven.config;

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

// 使用@Configuration标示为配置类
@Configuration
public class MainConfig {

    //如果不指定id，则默认为方法名。
    @Bean
    public Person person(){
        Person person = new Person();
        person.setAge(18);
        person.setName("leven");
        return new Person("leven",18);
    }

    //指定value后容器中的id为指定的值
    @Bean(value = "person_01")
    public Person person01(){
        Person person = new Person();
        person.setAge(18);
        person.setName("leven");
        return new Person("leven",18);
    }
}

2、主程序中获取配置类bean

ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
Object  person = applicationContext.getBean("person");
System.out.println(person);

// 获取person在容器中的名称
String[] namesForType = applicationContext.getBeanNamesForType(Person.class);
for (String name : namesForType) {
    System.out.println(name);
}

3、结果

可以看到person01在容器中的id为自己指定的value值person_01

Person{name='leven', age=18}
person
person_01