一、定义类实现EnvironmentPostProcessor

package cn.edu.tju.processor;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.env.EnvironmentPostProcessor;
import org.springframework.boot.env.YamlPropertySourceLoader;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.PropertySource;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

import java.io.IOException;

@Configuration
public class MyEnvironmentPostProcessor implements EnvironmentPostProcessor {
    private final YamlPropertySourceLoader loader = new YamlPropertySourceLoader();
    @Override
    public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
        System.out.println("in my environment post processor......");
        Resource path = new ClassPathResource("com/example/myapp/config.yml");
        PropertySource<?> propertySource = loadYaml(path);
        environment.getPropertySources().addLast(propertySource);

    }

    private PropertySource<?> loadYaml(Resource path) {
        try {
            return this.loader.load("custom-resource", path).get(0);
        }
        catch (IOException ex) {
            throw new IllegalStateException("Failed to load yaml configuration from "
                    + path, ex);
        }
    }

}

二、在resources目录建立com/example/myapp目录，然后在其中建立config.yml

school: tju

三、在resources下建立META-INF目录，并建立spring.factories文件

org.springframework.boot.env.EnvironmentPostProcessor=cn.edu.tju.processor.MyEnvironmentPostProcessor

四、在controller中使用上面已经注入到环境中的变量

package cn.edu.tju.controller;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DemoController {
    @Value("${school}")
    private String school;

    @RequestMapping("/test")
    public String test(){
        return school;
    }
}