1.添加pom依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
</dependency>

 2.application.yml文件中添加需要配置的属性,注意缩进

Myyml:
  username: cs
  password: 123456
  url: jdbc:mysql://localhost:3306/test
  driver: com.mysql.jdbc.Driver

 3.新建一个类,@Component注解表明是组件,可被自动发现,@ConfigurationProperties注解之前是location属性表明配置文件位置,prefix表示读取的配置信息的前缀,但新版本中废除了location属性(网上说是1.5.2之后),故只写前缀,默认读取application.yml中数据。重点!!一定要在这个类中写getter和setter,否则配置中的属性值无法自动注入

package com.cs.background.util;


import lombok.ToString;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;


@Component
@ConfigurationProperties(prefix = "Myyml")
public class User{
    //数据库连接相关
    private String url;
    private String driver;
    private String username;
    private String password;

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getDriver() {
        return driver;
    }

    public void setDriver(String driver) {
        this.driver = driver;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

 4.Controller类中执行自动注入,获取属性

//自动注入    
@Autowired
private User user;
//方法体内获取属性值 String url=user.getUrl();
System.out.print(url);

 5.启动springboot入口类,调用对应controller对应的方法,控制台打印获取的值。