idea建立普通Web專案lib目錄無法輸出，tomcat不報錯問題

idea版本：2021.2

tomcat版本：9.0.50

專案結構

建立一個普普通通的web專案，目錄結構大概就是這樣

.

├── .idea

│   ├── artifacts

│   ├── inspectionProfiles

│   ├── libraries

│   └── sonarlint

│       └── issuestore

├── conf

├── lib

├── out

│   ├── artifacts

│   │   └── test03_war_exploded

│   │       └── WEB-INF

│   │           ├── classes

│   │           │   └── top

│   │           │       └── ctong

│   │           │           └── controller

│   │           └── lib

│   └── production

│       └── test03

│           ├── generated

│           └── top

│               └── ctong

│                   └── controller

├── src

│   └── top

│       └── ctong

│           └── controller

└── web

    └── WEB-INF

lib資料夾已經設定為Library資料夾。

controller搞了個hello請求

@Controller

public class TestController implements Serializable {

    private static final long serialVersionUID = 6290967590153117614L;

    @RequestMapping("/hello")

    public void test01() {

        System.out.println("Hello World!");

    }

}

配置了自動包掃描

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xmlns:context="http://www.springframework.org/schema/context"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd

       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd

       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="top.ctong"/>

</beans>

載入了DispatcherServlet

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"

         version="4.0">

    <servlet>

        <servlet-name>dispatcherServlet</servlet-name>

        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

        <init-param>

            <param-name>contextConfigLocation</param-name>

            <param-value>classpath:springmvc.xml</param-value>

        </init-param>

    </servlet>

    <servlet-mapping>

        <servlet-name>dispatcherServlet</servlet-name>

        <url-pattern>/</url-pattern>

    </servlet-mapping>

</web-app>

問題

點啟動，訪問/hello成功榮獲404….幹掉out目錄重啟….404…

重新建一個專案，啟動…..hello world…..

再建立新專案，啟動…404…

開啟FileMerge檔案對比工具…嗯？差不多啊…

…開啟out資料夾，嗯？怎麼lib目錄沒加進來…

…反反覆覆2天后…

…

…

…

解決

嘗試將lib目錄拖進web/WEB-INF目錄…hello world…

不信邪，再把lib拖到專案根目錄…404…

……MMP……我之前一直這樣都沒問題…

不知道第幾次開啟 idea === >> Proiect Structure…

無意間點了 Proiect Settings ===>> Artifacts…嗯？怎麼有警告…..

Library lib ' required for module test03 is missing from the artifact 嗯？莫名其妙雙擊了右邊的lib。警告消失了…

啟動…hello world…

什麼妖魔鬼怪…