jsp+servlet+jdbc实现简单增删改查

傷城~ 2022-05-19 03:21 307阅读 0赞

今天在编程的时候又重新往前面学习jsp+servlet+jdbc做了一个小案例，希望能够程序猿们一点小启发，下篇博客会介绍在这个编程中可能遇到的问题。首先我们开始今天的案例;

首先所需要工具 ，以及开发环境

eclipse+mysql5.1+navicat foe mysql 这些工具是基本开发都会用到的

开发环境 jdk1.8以上 ，其实都无所谓。能搭建好tomcat就行 。

开始建web工程，整体结构如图一个实体 处理的servlet 以及需要的试图jsp文件

user![70][]

user.java实体类 数据库根据实体图建属性一致就行

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 <td> public class User { &nbsp;&nbsp; &nbsp;private Integer id; &nbsp;&nbsp; &nbsp;private String name; &nbsp;&nbsp; &nbsp;private Integer age; &nbsp;&nbsp; &nbsp;private String tel; &nbsp;&nbsp; &nbsp;public Integer getId() { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return id; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;public void setId(Integer id) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;this.id = id; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;public String getName() { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return name; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;public void setName(String name) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;this.name = name; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;public Integer getAge() { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return age; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;public void setAge(Integer age) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;this.age = age; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;public String getTel() { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return tel; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;public void setTel(String tel) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;this.tel = tel; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;@Override &nbsp;&nbsp; &nbsp;public String toString() { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return "User [name=" + name + ", age=" + age + ", tel=" + tel + "]"; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp; } &nbsp;</td> 
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工具类：一般在开发过程中都会用到 就封装一个类

JdbcUtils.java

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 <td> import java.sql.DriverManager; import java.sql.SQLException; import com.mysql.jdbc.Connection; public &nbsp;class JdbcUtils { &nbsp;&nbsp; &nbsp;public static Connection getConn() { &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;String driver = "com.mysql.jdbc.Driver"; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;String url = "jdbc:mysql://localhost:3306/test_yuanping"; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;String username = "root"; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;String password = "root"; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;Connection conn = null; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;try { &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Class.forName(driver); // &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;conn = (Connection) DriverManager.getConnection(url, username, password); &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;} catch (ClassNotFoundException e) { &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;e.printStackTrace(); &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;} catch (SQLException e) { &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;e.printStackTrace(); &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;} &nbsp;&nbsp; &nbsp; &nbsp; &nbsp;return conn; &nbsp;&nbsp; &nbsp;} } &nbsp; </td> 
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**之后就是增删改查的servlet 每个servlet都有标识**

**FindServlet**

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 <td> import java.io.IOException; import java.sql.ResultSet; import java.util.ArrayList; import java.util.List; 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.mysql.jdbc.Connection; import com.mysql.jdbc.Statement; import com.yp.pojo.User; import com.yp.utils.JdbcUtils; @WebServlet("/FindServlet") public class FindServlet extends HttpServlet { &nbsp;&nbsp; &nbsp;/** &nbsp;&nbsp; &nbsp; *&nbsp; &nbsp;&nbsp; &nbsp; */ &nbsp;&nbsp; &nbsp;private static final long serialVersionUID = 1L; &nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;@Override &nbsp;&nbsp; &nbsp;protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; try {&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;Connection conn=JdbcUtils.getConn(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;String sql="select * from users"; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;Statement st=(Statement) conn.createStatement(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;ResultSet resultSet = st.executeQuery(sql); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;List&lt;User&gt; list = new ArrayList&lt;User&gt;();&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;while(resultSet.next()) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;User user=new User(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;user.setId(resultSet.getInt("id")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;user.setAge(resultSet.getInt("age")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;user.setName(resultSet.getString("name")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;user.setTel(resultSet.getString("tel")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;list.add(user); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;req.setAttribute("list", list); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;resultSet.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;st.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;}catch (Exception e) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO: handle exception &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;e.printStackTrace(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; req.getRequestDispatcher("list.jsp").forward(req, resp); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;@Override &nbsp;&nbsp; &nbsp;protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO Auto-generated method stub &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;super.doPost(req, resp); &nbsp;&nbsp; &nbsp;} } </td> 
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**InsertServlet, DeleteServlet, UpdateServlet分别如下**

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 <td> import java.io.IOException; import java.sql.SQLException; 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.mysql.jdbc.Connection; import com.mysql.jdbc.PreparedStatement; import com.yp.utils.JdbcUtils; /** &nbsp;* Servlet implementation class InsertSerlet &nbsp;*/ @WebServlet("/InsertServlet") public class InsertServlet extends HttpServlet { &nbsp;&nbsp; &nbsp;private static final long serialVersionUID = 1L; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String name1 = new String(request.getParameter("name").getBytes("iso-8859-1"),"utf-8");&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;System.out.println(name1); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String tel=request.getParameter("tel"); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;int age=Integer.valueOf(request.getParameter("age")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;try { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;Connection conn=JdbcUtils.getConn(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String sql="insert into users(name,age,tel) values(?,?,?)"; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;PreparedStatement ps=(PreparedStatement) conn.prepareStatement(sql); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.setString(1, name1); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.setInt(2, age); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.setString(3, tel); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;int i=ps.executeUpdate(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;System.out.println("success"+i); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;conn.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} catch (SQLException e) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO Auto-generated catch block &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;e.printStackTrace(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;response.sendRedirect("FindServlet"); &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;/** &nbsp;&nbsp; &nbsp; * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) &nbsp;&nbsp; &nbsp; */ &nbsp;&nbsp; &nbsp;protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO Auto-generated method stub &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;doGet(request, response); &nbsp;&nbsp; &nbsp;} } </td> 
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 <td> import java.io.IOException; import java.sql.SQLException; 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.mysql.jdbc.Connection; import com.mysql.jdbc.PreparedStatement; import com.yp.utils.JdbcUtils; /** &nbsp;* Servlet implementation class DeleteServlet &nbsp;*/ @WebServlet("/DeleteServlet") public class DeleteServlet extends HttpServlet { &nbsp;&nbsp; &nbsp;private static final long serialVersionUID = 1L; &nbsp;&nbsp; &nbsp;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String ids=request.getParameter("id"); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;int id=Integer.parseInt(ids); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;try { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;Connection conn=JdbcUtils.getConn(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;//预编译语句&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String sql="delete from users where id=?"; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;//Statement st=(Statement) conn.createStatement(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;PreparedStatement st=(PreparedStatement) conn.prepareStatement(sql); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;st.setInt(1, id); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;st.execute(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;//关流 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;st.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;conn.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;catch (SQLException e) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO Auto-generated catch block &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;e.printStackTrace(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;response.sendRedirect("FindServlet"); &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;/** &nbsp;&nbsp; &nbsp; * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) &nbsp;&nbsp; &nbsp; */ &nbsp;&nbsp; &nbsp;protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO Auto-generated method stub &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;doGet(request, response); &nbsp;&nbsp; &nbsp;} } &nbsp; </td> 
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 <td> import java.io.IOException; import java.sql.SQLException; 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.mysql.jdbc.Connection; import com.mysql.jdbc.PreparedStatement; import com.yp.utils.JdbcUtils; /** &nbsp;* Servlet implementation class UpdateServlet &nbsp;*/ @WebServlet("/UpdateServlet") public class UpdateServlet extends HttpServlet { &nbsp;&nbsp; &nbsp;private static final long serialVersionUID = 1L; &nbsp;&nbsp; &nbsp;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String tel=request.getParameter("tel"); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String name = new String(request.getParameter("name").getBytes("iso-8859-1"),"utf-8");&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;System.out.println(tel); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String ids=request.getParameter("id"); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;int id=Integer.parseInt(ids); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;int age=Integer.valueOf(request.getParameter("age")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;System.out.println(id); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;try { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;Connection conn=JdbcUtils.getConn(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;String sql="update users set tel=?,name=?,age=? where id=?"; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;PreparedStatement ps=(PreparedStatement) conn.prepareStatement(sql); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.setString(1, tel); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.setString(2, name); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.setInt(3, age); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.setInt(4, id); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.executeUpdate(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;conn.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} catch (SQLException e) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO Auto-generated catch block &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;e.printStackTrace(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;System.out.println("update &nbsp;success"); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;response.sendRedirect("FindServlet"); &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;/** &nbsp;&nbsp; &nbsp; * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) &nbsp;&nbsp; &nbsp; */ &nbsp;&nbsp; &nbsp;protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO Auto-generated method stub &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;doGet(request, response); &nbsp;&nbsp; &nbsp;} } &nbsp; </td> 
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**下面的SelectServlet是用来更改数据时表单回显用的**

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 <td> package com.yp.servlet; import java.io.IOException; import java.sql.ResultSet; 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.mysql.jdbc.Connection; import com.mysql.jdbc.PreparedStatement; import com.yp.pojo.User; import com.yp.utils.JdbcUtils; /** &nbsp;* Servlet implementation class SelectServlet &nbsp;*/ @WebServlet("/SelectServlet") public class SelectServlet extends HttpServlet { &nbsp;&nbsp; &nbsp;private static final long serialVersionUID = 1L; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;int id=Integer.valueOf(request.getParameter("id")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;try {&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;Connection conn=JdbcUtils.getConn(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;String sql="select * from users where id=? "; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;PreparedStatement ps=(PreparedStatement) conn.prepareStatement(sql); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;ps.setInt(1, id); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;ResultSet resultSet = ps.executeQuery(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;User user=new User(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;while(resultSet.next()) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;user.setId(resultSet.getInt("id")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;user.setAge(resultSet.getInt("age")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;user.setName(resultSet.getString("name")); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;user.setTel(resultSet.getString("tel"));&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;request.setAttribute("user", user); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;resultSet.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;ps.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;conn.close(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;}catch (Exception e) { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO: handle exception &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;e.printStackTrace(); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; request.getRequestDispatcher("update.jsp").forward(request, response); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp;} &nbsp;&nbsp; &nbsp;/** &nbsp;&nbsp; &nbsp; * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) &nbsp;&nbsp; &nbsp; */ &nbsp;&nbsp; &nbsp;protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;// TODO Auto-generated method stub &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;doGet(request, response); &nbsp;&nbsp; &nbsp;} } &nbsp; </td> 
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**jsp页面，index.jsp就是新增用的 ，list.jsp是操作界面，update.jsp是更新页面，以下是分别jsp页面代码**

<table style="width:500px;"> jsp页面 
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 <td> &lt;%@ page language="java" contentType="text/html; charset=utf-8" &nbsp;&nbsp; &nbsp;pageEncoding="utf-8"%&gt; &lt;!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"&gt; &lt;html&gt; &lt;head&gt; &lt;meta http-equiv="Content-Type" content="text/html; charset=utf-8"&gt; &lt;title&gt;Insert title here&lt;/title&gt; &lt;/head&gt; &lt;body&gt; &lt;center&gt; &nbsp;&nbsp; &nbsp;&lt;h2&gt;add page&lt;/h2&gt; &nbsp;&nbsp; &nbsp;&lt;form action="InsertServlet" method="post"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;name:&lt;input type="text" name="name" &gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;br&gt;&lt;br&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;age:&lt;input type="text" name="age"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;br&gt;&lt;br&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;tel:&lt;input type="text" name="tel"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;br&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;input type="submit" value="add"&gt; &nbsp;&nbsp; &nbsp;&lt;/form&gt; &lt;/center&gt; &lt;/body&gt; &lt;/html&gt; </td> 
 </tr> 
 <tr> 
 <td>&lt;%@ page language="java" contentType="text/html; charset=utf-8" &nbsp;&nbsp; &nbsp;pageEncoding="utf-8"%&gt; &lt;%@page import="java.util.List"%&gt; &lt;%@page import="com.yp.pojo.User"%&gt; &lt;!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"&gt; &lt;html&gt; &lt;head&gt; &lt;meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"&gt; &lt;title&gt;Insert title here&lt;/title&gt; &lt;/head&gt; &lt;body&gt; &nbsp;&nbsp; &nbsp;&lt;center&gt; &nbsp;&nbsp; &nbsp;&lt;h1&gt;USER LIST&lt;/h1&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;table cellpadding="10" cellspacing="0" border="1"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;tr&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;id&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;name&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;age&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;tel&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;操作&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;/tr&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;% &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;List&lt;User&gt; list=(List&lt;User&gt;)request.getAttribute("list"); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; if (list == null || list.size() &lt; 1) {&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;out.print("没有数据！");&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; } else {&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;// 遍历图书集合中的数据&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;for (User user : list) {&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;%&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;tr&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;&lt;%=user.getId()%&gt;&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;&lt;%=user.getName()%&gt;&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;&lt;%=user.getAge()%&gt;&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt;&lt;%=user.getTel()%&gt;&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;a href="DeleteServlet?id=&lt;%=user.getId()%&gt;"&gt; 删除&lt;/a&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;a href="SelectServlet?id=&lt;%=user.getId()%&gt;"&gt; 修改&lt;/a&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;/td&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;/tr&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;%&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; %&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;/table&gt; &nbsp;&nbsp; &nbsp;&lt;/center&gt; &lt;/body&gt; &lt;/html&gt;</td> 
 </tr> 
 <tr> 
 <td>&lt;%@ page language="java" contentType="text/html; charset=UTF-8" &nbsp; &nbsp; pageEncoding="UTF-8"%&gt; &nbsp;&lt;%@page import="com.yp.pojo.User"%&gt; &lt;!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"&gt; &lt;html&gt; &lt;head&gt; &lt;meta http-equiv="Content-Type" content="text/html; charset=UTF-8"&gt; &lt;title&gt;Insert title here&lt;/title&gt; &lt;/head&gt; &lt;body&gt; &nbsp;&nbsp; &nbsp;&lt;center&gt; &nbsp;&nbsp; &nbsp;&lt;h1&gt;USER Update&lt;/h1&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;% &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;User user=(User)request.getAttribute("user"); &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;%&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;form action="UpdateServlet" method="post"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;input type="hidden" name="id" value="&lt;%=user.getId()%&gt;"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;name:&lt;input type="text" name="name" value="&lt;%=user.getName()%&gt;"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;br&gt;&lt;br&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;age:&lt;input type="text" name="age" value="&lt;%=user.getAge()%&gt;"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;br&gt;&lt;br&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;tel:&lt;input type="text" name="tel" value="&lt;%=user.getTel()%&gt;"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;br&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;input type="submit" value="update"&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&lt;/form&gt; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &lt;/body&gt; &lt;/html&gt;</td> 
 </tr> 
 </tbody> 
</table>

完成后效果图：

![70 1][]![70 2][]![70 3][]

有bug问题会在下篇更新。

[70]: /images/20220519/8447dbc4d03d45a7979bc8fee4132f2e.png
[70 1]: https://img-blog.csdn.net/20180719191025607?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc0MDU0MA==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 2]: https://img-blog.csdn.net/20180719191048148?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc0MDU0MA==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 3]: /images/20220519/db61d70b9cd24c61878737f571e6bbba.png