1. package com.itbaizhan.servlet;
    3. import java.io.*;
    4. import javax.servlet.*;
    5. import javax.servlet.http.*;
    7. public class HelloWorld extends HttpServlet{
    8.     public void doGet(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
    9.         PrintWriter printWriter = response.getWriter();
    10.         printWriter.println("<!DOCTYPE html>");
    11.         printWriter.println("<html lang=en>");
    12.         printWriter.println("<head>");
    13.         printWriter.println("<meta charset=UTF-8>");
    14.         printWriter.println("<title>Document</title>");
    15.         printWriter.println("</head>");
    16.         printWriter.println("<body>");
    17.         printWriter.println("<font color=blue>HelloWorld</font>");
    18.         printWriter.println("</body>");
    19.         printWriter.println("</html>");
    20.         printWriter.flush();
    21.         printWriter.close();
    22.     }
    23. }

    手动编译：
    javac -classpath “D:\javaStudy\apache-tomcat-9.0.64-windows-x64\apache-tomcat-9.0.64\lib\servlet-api.jar” HelloWorld.java