Spring中Bean的属性赋值@Value()---使用类配置的方式

person.nickName=小张三

package com.atguigu.config;
 
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
 
import com.atguigu.bean.Person;
 
//使用@PropertySource读取外部配置文件中的k/v保存到运行的环境变量中;加载完外部的配置文件以后使用${}取出配置文件的值
@PropertySource(value={"classpath:/person.properties"})
@Configuration
public class MainConfigOfPropertyValues {
    
    @Bean
    public Person person(){
        return new Person();
    }
 }

package com.atguigu.bean;
 
import org.springframework.beans.factory.annotation.Value;
 
public class Person {
    
    //使用@Value赋值；
    //1、基本数值
    //2、可以写SpEL； #{}
    //3、可以写${}；取出配置文件【properties】中的值（在运行环境变量里面的值）
    
    @Value("张三")
    private String name;
    @Value("#{20-2}")
    private Integer age;
    
    @Value("${person.nickName}")
    private String nickName;
    
    
    
    public String getNickName() {
        return nickName;
    }
    public void setNickName(String nickName) {
        this.nickName = nickName;
    }
    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 Person(String name, Integer age) {
        super();
        this.name = name;
        this.age = age;
    }
    public Person() {
        super();
        // TODO Auto-generated constructor stub
    }
    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + ", nickName=" + nickName + "]";
　　}
}

<context:property-placeholder location="classpath:person.properties"/>
    <!-- 包扫描、只要标注了@Controller、@Service、@Repository，@Component -->
    <context:component-scan base-package="com.atguigu" use-default-filters="false"></context:component-scan>
    <bean id="person" class="com.atguigu.bean.Person"  >
        <property name="age" value="#{20-2}"></property>
        <property name="name" value="小张三"></property>
        <property name="nickName" value="${person.nickName}"></property>

</bean>

package com.atguigu.test;
 
import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
 
import com.atguigu.bean.Person;
import com.atguigu.config.MainConfigOfLifeCycle;
import com.atguigu.config.MainConfigOfPropertyValues;
 
public class IOCTest_PropertyValue {
    AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigOfPropertyValues.class);
    @Test
    public void test01(){
        printBeans(applicationContext);
        System.out.println("=============");
        
        Person person = (Person) applicationContext.getBean("person");
        System.out.println(person);
        
        applicationContext.close();
    }
    
    //打印spring启动后加载的对象
    private void printBeans(AnnotationConfigApplicationContext applicationContext){
        String[] definitionNames = applicationContext.getBeanDefinitionNames();
        for (String name : definitionNames) {
            System.out.println(name);
        }
    }
 
}