Web 项目如何读取外部配置文件

import java.io.File;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.config.YamlPropertiesFactoryBean;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.env.EnvironmentPostProcessor;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.MutablePropertySources;
import org.springframework.core.env.PropertiesPropertySource;
import org.springframework.core.io.FileSystemResource;
import org.springframework.stereotype.Component;
@Component
@Slf4j
public class MyEnvironmentPostProcessor implements EnvironmentPostProcessor {
    private static final String mainYml = "application.yml";
    @Override
    public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
        String parent = System.getProperty("application.path");
        File parentFile = new File(parent);
        if(!parentFile.exists()){
            throw new NullPointerException("外部配置文件为空");
        }else {
            log.info("开始加载外部配置文件");
            File main = loadYml(parent);
            File active = loadMainYml(parent);
            YamlPropertiesFactoryBean mainYml = new YamlPropertiesFactoryBean();
            YamlPropertiesFactoryBean yaml = new YamlPropertiesFactoryBean();
            mainYml.setResources(new FileSystemResource(main));
            yaml.setResources(new FileSystemResource(active));
            MutablePropertySources propertySources = environment.getPropertySources();
            propertySources.addFirst(new PropertiesPropertySource(main.getName(), mainYml.getObject()));
            propertySources.addFirst(new PropertiesPropertySource(active.getName(), yaml.getObject()));
        }
    }
    public File loadYml(String parent){
        String main = parent + File.separator + mainYml;
        return new File(main);
    }
    public File loadMainYml(String parent){
        YamlPropertiesFactoryBean yaml = new YamlPropertiesFactoryBean();
        String main = parent + File.separator + mainYml;
        File mainFile = new File(main);
        if(mainFile.exists()){
            yaml.setResources(new FileSystemResource(mainFile));
            String active = yaml.getObject().getProperty("spring.profiles.active");
            String envFile = parent + File.separator + "application-" + active + ".yml";
            return new File(envFile);
        }
        return null;
    }
}