spring属性赋值@Value赋值与@PropertySource加载外部配置文件

1.实体类

package com.hjj.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 + "]";
	}
}

2.创建一个配置类

package com.hjj.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

import com.hjj.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"})
//告诉sring容器这是一个配置类
@Configuration
public class MainConfigOfPropertyValues {
	
	//给容器中添加一个person
	@Bean
	public Person person(){
		return new Person();
	}

}

3.创建一个测试类

package com.hjj.test;

import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;

import com.hjj.bean.Person;
import com.hjj.config.MainConfigOfLifeCycle;
import com.hjj.config.MainConfigOfPropertyValues;

public class IOCTest_PropertyValue {
    // 加载步骤2中的MainConfigOfPropertyValues配置类
	AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigOfPropertyValues.class);
	@Test
	public void test01(){
	    // 打印容器中所有bean
		printBeans(applicationContext);
		System.out.println("=============");
		
		Person person = (Person) applicationContext.getBean("person");
		System.out.println(person);
		
		// 配置文件中的值被获取之后，可以使用该方法获取配置文件中的值（配置文件中的值都会被加载进环境变量中）
		ConfigurableEnvironment environment = applicationContext.getEnvironment();
		String property = environment.getProperty("person.nickName");
		System.out.println(property);
		applicationContext.close();
	}
	
	private void printBeans(AnnotationConfigApplicationContext applicationContext){
		String[] definitionNames = applicationContext.getBeanDefinitionNames();
		for (String name : definitionNames) {
			System.out.println(name);
		}
	}
}