Spring Boot默认配置文件加载顺序（四）

通常情况下，Spring Boot 在启动时会将 resources 目录下的 application.properties 或 apllication.yml 作为其默认配置文件，我们可以在该配置文件中对项目进行配置，如果当项目中存在多个 application.properties 或 application.yml时，那应该优先加载哪个配置文件呢？

一、默认配置文件加载顺序

当Spring Boot 项目中可以存在多个 application.properties 或 apllication.yml时，Spring Boot 启动时会扫描以下 5 个位置的 application.properties 或 apllication.yml 文件，并将它们作为 Spring boot 的默认配置文件。以下是加载默认配置文件的优先级顺序，从高到底，高优先级的配置可以覆盖低优先级的配置信息：

1> file:./config/*/

2> file:./config/

3> file:./

4> classpath:/config/

5> classpath:/

其中，file表示项目的根目录；classpath表示项目的类路径，即resources目录。如下举例：

二、项目举例

1.项目结构

2.代码实现

MainApplication.java:

package com.xj.main;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

/**
 * @Author : xjfu
 * @Date : 2022/6/8 8:38
 * @Description :Spring Boot 启动类
 */
@ComponentScan("com.xj")
@SpringBootApplication
public class MainApplication {
    public static void main(String[] args) {
        SpringApplication.run(MainApplication.class, args);
    }
}

HelloController.java:

package com.xj.controller;

import com.xj.entity.PersonOne;
import com.xj.entity.PersonTwo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * @Author : xjfu
 * @Date : 2022/6/8 8:47
 * @Description :
 */
@Controller
public class HelloController {

    @Autowired
    private PersonOne personOne;

    @Autowired
    private PersonTwo personTwo;

    @ResponseBody
    @RequestMapping(value = "/hello")
    public String sayHello(){
        return "Hello ! Spring Boot Project Jar Test!";
    }

    @ResponseBody
    @RequestMapping(value = "/personOne")
    public PersonOne getPersonOne(){
        return personOne;
    }

    @ResponseBody
    @RequestMapping(value = "/personTwo")
    public PersonTwo getPersonTwo(){
        return personTwo;
    }

}

PersonOne.java:

package com.xj.entity;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
import java.util.List;
/**
 * @Author : xjfu
 * @Date : 2022/6/24 9:01
 * @Description :
 */
/**
 * @ConfigurationProperties：告诉SpringBoot将本类中的所有属性和配置文件中相关的配置进行绑定；
 *                           prefix = "person"：配置文件中哪个下面的所有属性进行一一映射
 */
@Component
@ConfigurationProperties(prefix = "person")
public class PersonOne {

    private String name;

    private Integer age;

    private List<String> pets;

    private List<String> food;

    private Child child;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public List<String> getPets() {
        return pets;
    }

    public void setPets(List<String> pets) {
        this.pets = pets;
    }

    public List<String> getFood() {
        return food;
    }

    public void setFood(List<String> food) {
        this.food = food;
    }

    public Child getChild() {
        return child;
    }

    public void setChild(Child child) {
        this.child = child;
    }
}

Child.java:

package com.xj.entity;

/**
 * @Author : xjfu
 * @Date : 2022/7/5 8:31
 * @Description :
 */
public class Child {

    private String name;

    private Integer age;

    private String gender;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }
}

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.xj.study</groupId>
    <artifactId>spring-boot-study-project</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.5</version>
        <relativePath/>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

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

    <!--build标签描述了如何来编译及打包项目，而具体的编译和打包工作是通过build中配置的 plugin 来完成-->
    <build>
        <plugins>
            <!--使用SpringBoot的打包插件-->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

五个配置文件：

1>SpringBootStudyProject\config\release\application.yml:

person:
    name: ss
    age: 25
    pets: [pig1,dog1,cat1]
    food:
        - HuiMian1
        - YouPoMian1
        - HeLuo1

2>SpringBootStudyProject\config\application.yml

server:
    servlet:
        context-path: /abc

3>SpringBootStudyProject\application.yml

server:
    port: 8084
    servlet:
        context-path: /helloworld

4>resources\config\application.yml

server:
    port: 8081

5>resources\application.yml

server:
    servlet:
        context-path: /hello
person:
    name: dave
    age: 18
    pets: [pig,dog,cat]
    food:
        - HuiMian
        - YouPoMian
        - HeLuo
    child:
        name: ss
        age: 13
        gender: female