实现导入HttpServlet

<!--        Servlet依赖-->

        <dependency>

            <groupId>javax.servlet</groupId>

            <artifactId>javax.servlet-api</artifactId>

            <version>3.1.0</version>

            <scope>provided</scope>

        </dependency>

<!--        JSP依赖-->

        <dependency>

            <groupId>javax.servlet.jsp</groupId>

            <artifactId>javax.servlet.jsp-api</artifactId>

            <version>2.3.3</version>

            <scope>provided</scope>

        </dependency>

<!--        jstl表达式的依赖-->

        <dependency>

            <groupId>javax.servlet</groupId>

            <artifactId>jstl</artifactId>

            <version>1.2</version>

        </dependency>

<!--        standar标签库-->

        <dependency>

            <groupId>taglibs</groupId>

            <artifactId>standard</artifactId>

            <version>1.1.2</version>

        </dependency>