不灭的焱

方式一：配置IDEA

1. 打开项目结构对话框：File -> Project Structure

2. 配置IDEA的 Platform Setting -> Global Libraries 或 Project Settings -> Libraries

方式二：【推荐】配置pom.xml文件

<!--++++++++++++++++++++++++++++++++++++++++++++++++++++-->
<!-- Servlet环境：引入servlet-api和jsp-api -->
<!--++++++++++++++++++++++++++++++++++++++++++++++++++++-->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.0.1</version>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>jsp-api</artifactId>
    <version>2.2</version>
    <scope>provided</scope>
</dependency>