JSP案例_简单实现用户信息的增、删、查、改

不念不忘少年蓝@ 2022-06-12 03:06 939阅读 0赞

**JSP案例\_简单实现用户信息的增、删、查、改**

**1.案例要求**

> **一个简单的jsp页面与mysql的结合，实现用户信息的增、删、查、改的案例**
> 
>   
>

**2.案例分析**

> **（1）在mysql创建数据库，创建用户表**
> 
> **（2）创建对应的jsp页面**
> 
> **（3）在jsp文件中连接数据库，获取输入值，进行对应的数据库操作**
> 
>   
>

**3.代码分析**

> **（1）数据库设计：简单的用户表，为了简单，只有两列**
> 
> **（2）JSP页面设计注重实现功能，界面简单粗暴！**
> 
>   
>

**4.代码实现**

> **(1)数据库代码-sql语句：**
> 
>     CREATE DATABASE test;
>     USE test;
>     -- 用户表
>     CREATE TABLE USER(
>     id INT PRIMARY KEY AUTO_INCREMENT,
>     NAME VARCHAR(20)
>     )
> 
>   
> 
> 
> **(2)JSP代码：**

> **index.jsp:**
> 
>     <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
>     <form action="doadd.jsp">
>     	<h2>数据录入</h2>
>     	输入姓名：
>     	<input type="text" name="username" />
>     	<button type="submit">插入数据</button>
>     </form>
> 
> **doadd.jsp:**
> 
>     <%@page import="java.sql.*"%>
>     <%@page import="com.mysql.jdbc.Driver"%>
>     <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
>     <%
>     	//获取传递过来的数据
>     	String name = request.getParameter("username");
>     	//out.print(name);
>     	//加载驱动
>     	Class.forName("com.mysql.jdbc.Driver");
>     	String url = "jdbc:mysql://localhost:3306/test";
>     	String user = "root";
>     	String password = "root";
>     	//获取连接对象
>     	Connection conn = DriverManager.getConnection(url, user, password);
>     	//定义sql语句
>     	String sql = "insert into user values(null,?)";
>     	//预编译
>     	PreparedStatement stmt = conn.prepareStatement(sql);
>     	//设置参数
>     	stmt.setString(1, name);
>     	//执行参数
>     	int count = stmt.executeUpdate();
>     	/* if(count!=0){
>     		out.print("插入成功！");
>     	} */
>     	conn.close();
>      %>
>      <script type="text/javascript">
>     	window.location = "show.jsp";
>     </script>
> 
> **dodel.jsp:**
> 
>     <%@page import="java.sql.*"%>
>     <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
>     <% 
>     	//获取传递过来的id
>     	String i = request.getParameter("id");
>     	int id = Integer.parseInt(i);
>     	//out.print(id);
>     	//加载驱动
>     	Class.forName("com.mysql.jdbc.Driver");
>     	//获取连接对象
>     	String url = "jdbc:mysql://localhost:3306/test";
>     	String user = "root";
>     	String password = "root";
>     	Connection conn = DriverManager.getConnection(url, user, password);	
>     	//定义sql语句
>     	String sql = "delete from user where id=?;";
>     	//预编译
>     	PreparedStatement stmt = conn.prepareStatement(sql);
>     	//设置参数
>     	stmt.setInt(1, id);
>     	//执行
>     	int count = stmt.executeUpdate();
>     %>
>     <script type="text/javascript">
>     	window.location = "show.jsp";
>     </script>
> 
> **doupdate.jsp:**
> 
>     <%@page import="java.sql.*"%>
>     <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
>     <% 
>     	//获取
>     	String newname = request.getParameter("newname");
>     	String idString = request.getParameter("id");
>     	int id = Integer.parseInt(idString);
>     	Class.forName("com.mysql.jdbc.Driver");
>     	String url = "jdbc:mysql://localhost:3306/test";
>     	String user = "root";
>     	String password = "root";
>     	Connection conn = DriverManager.getConnection(url, user, password);
>     	String sql = "update user set name=? where id=?;";
>     	PreparedStatement stmt = conn.prepareStatement(sql);
>     	stmt.setString(1, newname);
>     	stmt.setInt(2, id);
>     	int count = stmt.executeUpdate();
>     %>
>     <script>
>     	window.location="show.jsp";
>     </script>
> 
> **show.jsp:**
> 
>     <%@page import="java.sql.*"%>
>     <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
>     	当前所有用户列表：
>     <table border="2" width="300">
>     	<tr>
>     		<td>id</td>
>     		<td>姓名</td>
>     		<td>删除操作</td>
>     		<td>修改操作</td>
>     	</tr>
>     <%
>     	//加载驱动
>     	Class.forName("com.mysql.jdbc.Driver");
>     	//获取连接对象
>     	String url = "jdbc:mysql://localhost:3306/test";
>     	String user = "root";
>     	String password = "root";
>     	Connection conn = DriverManager.getConnection(url, user, password);
>     	/* if(conn!=null){
>     		out.print("123");
>     	} */
>     	//定义sql语句
>     	String sql = "select * from user;";
>     	//预编译
>     	PreparedStatement stmt = conn.prepareStatement(sql);
>     	//执行
>     	ResultSet rs = stmt.executeQuery();
>     	//数据显示
>     	while(rs.next()){
>     		//out.print(rs.getInt("id")+"-"+rs.getString("NAME"));
>     %>
>     	<tr>
>     		<td><%=rs.getInt("id") %></td>
>     		<td><%=rs.getString("NAME") %></td>
>     		<td><a href="dodel.jsp?id=<%=rs.getInt("id") %>">删除</a></td>
>     		<td><a href="showupdate.jsp?id=<%=rs.getInt("id") %>">修改</a></td>
>     	</tr>
>     <% 
>     	}
>     	conn.close();
>      %>
>     </table>
>     <a href="index.jsp">继续添加</a>
> 
> **showupdate.jsp:**
> 
>     <%@page import="java.sql.*"%>
>     <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
>     	当前信息：
>     	<br />
>     <table border="2" width="300">
>     	<tr>
>     		<td>id</td>
>     		<td>当前姓名</td>
>     	</tr>
>     <% 
>     	String idString = request.getParameter("id");
>     	int id = Integer.parseInt(idString);
>     	Class.forName("com.mysql.jdbc.Driver");
>     	String url = "jdbc:mysql://localhost:3306/test";
>     	String user = "root";
>     	String password = "root";
>     	Connection conn = DriverManager.getConnection(url, user, password);
>     	String sql = "select * from user where id=?;" ;
>     	PreparedStatement stmt = conn.prepareStatement(sql);
>     	stmt.setInt(1, id);
>     	ResultSet rs = stmt.executeQuery();
>     	while(rs.next()){
>     %>
>     	<tr>
>     		<td><%=rs.getInt("id") %></td>
>     		<td><%=rs.getString("name") %></td>
>     	</tr>
>     <% 
>     	}
>     %>
>     </table>
>     <form action="doupdate.jsp">
>     	请输入新的姓名:
>     	<input type="hidden" value="<%=request.getParameter("id") %>" name="id"/> 
>     	<input type="text" name="newname"/>
>     	<button type="submit">确认修改</button>
>     </form>
> 
>   
>

**5.运行截图**

> **数据录入：**

> **![Center][]**  
> 
> 
> **![Center 1][]**  
> 
> 
> **数据显示：**
> 
> **![Center 2][]**
> 
> **数据删除：**
> 
> ![Center 3][]
> 
> **数据修改：**
> 
> ![Center 4][]  
> 
> 
> ![Center 5][]  
>

**6.案例总结**

> **（1）注意web项目的部署和Tomcat的启动，mysql服务的启动**
> 
> **（2）如果代码正确刷新不出来，建议重新部署web项目，重启Tomcat**
> 
> **（3）注意导java包**
> 
> **（4）注意jdbc的语法以及驱动的导入，可参照前面的文章**
> 
> **（5）注意JSP页面里java代码和html代码的配合使用**
> 
> **（6）注意sql语句的正确编写**
> 
> **（7）注意加载驱动的语句**
> 
> **（8）预编译sql语句之后还要执行**
> 
> **（9）注意给预编译sql语句设置参数**
> 
> **（10）注意url的语法，用户名以及密码的正确性**

>   
> 
> 
>   
>

[Center]: /images/20220612/c38d2122edf74326b2f2d4ee3654f1b7.png
[Center 1]: /images/20220612/80053691f5b54ae1b7283f78babe3527.png
[Center 2]: /images/20220612/2f6d4b1393b0434aa758873305e292a2.png
[Center 3]: /images/20220612/8e4a100a41f640ad9d4f859861f93832.png
[Center 4]: /images/20220612/3aab1f02f1e04e90bb610fdcf718c278.png
[Center 5]: /images/20220612/6d065fe119bc4e179dd0961aea7dad61.png