How to write a servlet program JavaWeb ------

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5. Add dependent servlet

<dependencies>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>4.0.1</version>
    </dependency>
</dependencies>

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12. web.xml changes to the latest version

<?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"
         metadata-complete="true">
  
</web-app>

13. New resources and two packages java

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15. The construction of the package, write code

public class HelloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("进入doGet方法");

        PrintWriter writer = resp.getWriter();
        writer.print("I MISS YOU");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

16. The preparation of the servlet mapping Web.xml

<servlet>
    <servlet-name>helloServlet</servlet-name>
    <servlet-class>com.yang.servlet.HelloServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>helloServlet</servlet-name>
    <url-pattern>/hello</url-pattern>
</servlet-mapping>

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21. Start Tomcat to enter index.jsp

22. The access path we set when mapping