方法一：@Value获取属性值

首先在application.properties中添加属性值

app.name=MyApp
app.description=${app.name} is a Spring Boot application

编写工具类，通过注解@Value获取属性值（类名这里就不讲究命名规范了）

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class Mytest {

    @Value("${app.name}")
    private String appName;

    @Value("${app.description}")
    private String appDescription;

    public String getAppName() {
        return appName;
    }
    public String getAppDescription() {
        return appDescription;
    }

}

调用工具类，输出属性值

import com.example.spdemo.Application;
import com.example.spdemo.Mytest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Index {
    @Autowired
    private Mytest mytest;

    @RequestMapping("/")
    public String HelloWorld(){
        System.out.println();
        System.out.println(mytest.getAppName());
        System.out.println(mytest.getAppDescription());
        return "Hello World !";
    }
}

方法二：@ConfigurationProperties

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@ConfigurationProperties(prefix = "app")
public class Index {
    private String name;
    private String description;

    @RequestMapping("/")
    public String getProps() {
        return name + "|" + description;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
}

如果配置没有app的前缀的话，去掉注解中的(prefix = "app")，保持属性名与类成员属性名一致即可。