关于增删改查的例子

DeleteServlet:

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package com.zh.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.zh.service.*;
@WebServlet("/DeleteServlet")
public class DeleteServlet extends HttpServlet {
    
       protected void service(HttpServletRequest arg0,HttpServletResponse arg1) 
               throws ServletException ,IOException{
           arg1.setContentType("text/html");
           arg0.setCharacterEncoding("GBK");
           arg1.setCharacterEncoding("GBK");
           String name=arg0.getParameter("teacher_name");
           Userservice service =new Userservice();
           service.deleteUser(name);
           try {
               arg0.getRequestDispatcher("/query").forward(arg0, arg1);
           }catch (Exception e) {
               e.printStackTrace();
           }
       }
    
   }
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InsertServlet:

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package com.zh.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zh.service.*;
@WebServlet("/InsertServlet")
public class InsertServlet extends HttpServlet {
    protected void service(HttpServletRequest req,HttpServletResponse res) 
            throws ServletException,IOException {
        res.setContentType("text/html");
        req.setCharacterEncoding("GBK");
        res.setCharacterEncoding("GBK");
        String place=req.getParameter("place");
        String teacher_name=req.getParameter("teacher_name");
        String class_name=req.getParameter("class_name");
        PrintWriter pw=res.getWriter();
        Userservice service=new Userservice();
        try {
            service.insertUser(place, teacher_name, class_name);
            pw.println("新增信息成功！");
            req.getRequestDispatcher("/query").forward(req, res);;
        }catch (Exception e) {
            e.printStackTrace();
            req.getRequestDispatcher("/insert.html").forward(req, res);
        }
    }

    
    

}
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QueryServlet:

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package com.zh.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
import com.zh.entity.*;
import com.zh.service.*;
import java.util.*;
@WebServlet("/QueryServlet")
public class QueryServlet extends HttpServlet {
    protected void service(HttpServletRequest req,HttpServletResponse res) 
            throws ServletException,IOException {
        res.setContentType("text/html");
        req.setCharacterEncoding("GBK");
        res.setCharacterEncoding("GBK");
        PrintWriter pw=res.getWriter();
        Userservice service=new Userservice();
        List list=service.findAll_user();
        pw.println("<html>");
        pw.println("<head>");
        pw.println("</head>");
        pw.println("<body>");
        pw.println("<table border='1' bordercolor='red' align='center'");
        pw.println("<tr>");
        pw.println("<td>");
        pw.println("地点");
        pw.println("</td>");
        pw.println("<td>");
        pw.println("教师名");
        pw.println("</td>");
        pw.println("<td>");
        pw.println("课程名");
        pw.println("</td>");
        pw.println("</tr>");
        for(int i=0;i<list.size();i++) {
        bean b=(bean) list.get(i);
        pw.println("<tr>");
        pw.println("<td>");
        pw.println(b.get_place());
        pw.println("</td>");
        pw.println("<td>");
        pw.println(b.get_teacher_name());
        pw.println("</td>");
        pw.println("<td>");
        pw.println(b.get_class_name());
        pw.println("/<td>");
        pw.println("<a href='/Web_operation1/delete?teacher_name="+b.get_teacher_name()+"'> 删 除   </a>||<a href='/Web_operation1/updata.html'>修改信息</a>" );
                pw.println("</td>");
                pw.println("</tr>");
        }
        pw.println("</table>");
        pw.println("</body>");
        pw.println("</html>");
        pw.flush();
        pw.close();
}
}
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UpdateServlet:

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package com.zh.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
import com.zh.service.*;

@WebServlet("/UpdataServlet")
public class UpdateServlet extends HttpServlet {
protected void service(HttpServletRequest req,HttpServletResponse res) 
        throws ServletException,IOException {
    res.setContentType("text/html");
    req.setCharacterEncoding("GBK");
    res.setCharacterEncoding("GBK");
    PrintWriter pw=res.getWriter();
    Userservice service=new Userservice();
    String place=req.getParameter("place");
    String teacher_name=req.getParameter("teacher_name");
    String class_name=req.getParameter("class_name");
    try {
        if (service.updataByteacher_name(place, class_name, teacher_name)) {
            res.sendRedirect("/Web_operation1/query");
        }
    }catch (Exception e) {
        e.printStackTrace();
    }
}
}
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insert.html:

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<!DOCTYPE HTML PUBLIC"-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta charset="UTF-8">
<title>Insert </title>
</head>
<body>
<center>
<form action="/Web_operation1/insert"medthod="post">
   <table border ="1" bordercolor="red"align="center">
   <tr>
   <td>
     上课地点：
     </td>
     <td>
     <input type="text" name="place"/>
     </td>
     
     </tr>
   <tr>
   <td>
   任课教师：
   </td>
   <td>
   <input type="text" name="teacher_name"/>
   </td>
   </tr>
   <tr>
   <td>
   课程名称：
   </td>
   <td>
   <input type="text" name="class_name"/>;
   </td>
   </tr>
   </table>
   </form>
   </center>              
</body>
</html>
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update.html:

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<!DOCTYPE HTML PUBLIC"-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta charset="UTF-8">
<title>update</title>
</head>
<body>
<center>
<form action="/Web_operation1/update" method="post">
<table border="1"bordercolor="red" align="center">
<tr>
<td> 上课地点：</td>
<td>
<input type="text" name="place">
</td>
</tr>
<tr>
<td> 任课教师：</td>
<td>
<input type="text" name="teacher_name">
</td>
</tr>
<tr>
<td> 课程名称：</td>
<td>
<input type="text"name="class_name">
</td>
</tr>
<tr>
 <td colspan="2"align="center">
 <input type="button" value="确认">
 </td>
 </tr>
</table>
</form>
</body>
</html>
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web.xml:

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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">
  <display-name>Web_operation1</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
  <servlet-name>query</servlet-name>
  <servlet-class>com.zh.servlet.QueryServlet</servlet-class>
  </servlet>
  <servlet-mapping>
  <servlet-name>query</servlet-name>
  <url-pattern>/query</url-pattern>
  </servlet-mapping>
  <servlet>
  <servlet-name>delete</servlet-name>
  <servlet-class>com.zh.servlet.DeleteServlet</servlet-class>
  </servlet>
  <servlet-mapping>
  <servlet-name>delete</servlet-name>
  <url-pattern>/delete</url-pattern>
  </servlet-mapping>
  <servlet>
  <servlet-name>update</servlet-name>
  <servlet-class>com.zh.servlet.UpdateServlet</servlet-class>
  </servlet>
  <servlet-mapping>
  <servlet-name>update</servlet-name>
  <url-pattern>/update</url-pattern>
  </servlet-mapping>
  <servlet>
  <servlet-name>insert</servlet-name>
  <servlet-class>com.zh.servlet.InsertServlet</servlet-class>
  </servlet>
  <servlet-mapping>
  <servlet-name>insert</servlet-name>
  <url-pattern>/insert</url-pattern>
  </servlet-mapping>
  
</web-app>
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原文地址：https://www.cnblogs.com/9635741zly/p/14916676.html