一、通過上下文

@SpringBootApplication  
public class SpringBoot01Application {  
  
    public static void main(String[] args) {  
        ConfigurableApplicationContext  context=SpringApplication.run(SpringBoot01Application.class, args);  
        String str1=context.getEnvironment().getProperty("aaa");  
        System.out.println(str1);  
    }  
}  
 

二、自動裝配倒bean

import org.springframework.beans.factory.annotation.Autowired;  
import org.springframework.beans.factory.annotation.Value;  
import org.springframework.core.env.Environment;  
import org.springframework.stereotype.Component;  
  
@Component  
public class Student {  
    @Autowired  
    
 
private Environment env;  
  
    public void speak() {  
        System.out.println("=========>" + env.getProperty("aaa"));  
    }  
}  

三、使用@Value註解

package com.example.demo.entity;    
    
import org.springframework.beans.factory.annotation.Value;    
import org.springframework.context.annotation.PropertySource;    
 
import org.springframework.stereotype.Component;    
    
@Component    
@PropertySource("classpath:jdbc.properties")//如果是application.properties，就不用寫@PropertySource("application.properties")，其他名字用些    
public class Jdbc {    
        
    @Value("${jdbc.user}")  
    private String user;    
        
    @Value("${jdbc.password}")   
    private String password;    
        
    public void speack(){    
        System.out.println("username:"+user+"------"+"password:"+password);    
    }    
}