SpringBoot有哪几种方式获取application.properties中的值呢？

下文笔者讲述SpringBoot获取application.properties中的值的方法分享，如下所示:

通过上下文environment环境变量获取属性值

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

自动装配到指定Bean

这个也是借助于environment

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 User {  
    @Autowired  
    private Environment env;  
  
    public void getUserName() {  
        System.out.println("==========" + env.getProperty("username"));  
    }  
}

使用@Value注解

package com.java265;    
    
import org.springframework.beans.factory.annotation.Value;    
import org.springframework.context.annotation.PropertySource;    
import org.springframework.stereotype.Component;    
    
@Component    
@PropertySource("classpath:jdbc.properties") 
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);    
    }    
}