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JSP + JDBC 技术对数据库进行增删改查操作_编写jsp页面通过使用jdbc技术实现对学生表中的数据增删改查

作者：知新_RL | 2024-05-15 23:05:41

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编写jsp页面通过使用jdbc技术实现对学生表中的数据增删改查

遇到了很多问题：

1.字符编码问题

error：Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.
解决：String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8";

主要是由于每个jsp文件的编码方式不同，数据库传过来的参数jsp页面无法识别，导致500错误；

2.数据库操作不对应

怪我数据库每学扎实，insert数据的时候忘记了table后面的参数：insert table（sno,sname） value(?,?)；

3.没有进行关联

这个困扰了我很久，驱动也放到了lib文件夹下面，就是一直报错；
解决：右击项目——>  build path  ——>  add jars  ——>找到目前项目对应的驱动包的位置即可；

3 问题图片

4.java web项目中如何引入css/js代码

  1. //文件的开始需要写这一段，以便写入绝对路径，相对路径容易访问失败
  2. <%
  3. 	String path = request.getContextPath();
  4. 	String basePath = request.getScheme() + "://" + request.getServerName() + ":" 
  5. 	+ request.getServerPort() +path + "/";
  6. %>

 然后head里面加入link即可，我的文档结构 ： sy3项目名称/css文件名/query.css

  1. <head>
  2. 	<link rel = "stylesheet" type = "text/css" href = "/sy3/css/query.css">
  3. </head>

疑问：

①  一个eclipse可以下载多个tomcat么？

答：可以，打开server窗口，需要用哪个tomcat就启动哪个，然后把项目部署到tomcat上，打开网址输入相应的端口号即可。

②  同时下载了mysql与sql server会冲突吗？

答：不会，两个数据库的驱动不一样，把对应的驱动放到lib文件下面，并写入完整的驱动代码即可。

③  驱动应该怎么下载？版本不对应会影响么？

答：一般没什么影响，我mysql是8.0版本的，驱动是5.0.8版本，可以正常启动。

基本步骤：

①  打开eclipse，新建项目Java web

②  部署驱动到lib文件夹，并与当前的项目关联

③  写代码

④  打开server窗口，将项目部署到tomcat中，启动tomcat

⑤  在浏览器窗户输入ip地址：http://localhost:8080/sy3/mysqlquery.jsp

附：源码

1.mysqlquery.jsp

  1. <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
  2. <%@page import="java.sql.*"%>
  3. <%
  4. 	String path = request.getContextPath();
  5. 	String basePath = request.getScheme() + "://" + request.getServerName() + ":" 
  6. 	+ request.getServerPort() +path + "/";
  7. %>
  8. <html>
  9. <head>
  10. 	<link rel = "stylesheet" type = "text/css" href = "/sy3/css/query.css">
  11. </head>
  12. <body>
  13. <div class = "dv1" align = "center">
  14. 	<span class="title">MYSQL数据库连接</span>
  15. </div>
  16. <%!   
  17.   public static final String DBDRIVER="com.mysql.jdbc.Driver";
  18.   
  19.   public static final String DBURL="jdbc:mysql://localhost:3306/test?characterEncoding=utf8";
  20.   public static final String DBUSER="root";
  21.   public static final String DBPASS="imshsyxxarsh";
  22. %>
  23. <% 
  24.    Connection conn=null;
  25.    PreparedStatement pstmt=null;
  26.    ResultSet rs=null;
  27.  
  28.    Class.forName(DBDRIVER);		//
  29.    conn=DriverManager.getConnection(DBURL,DBUSER,DBPASS);	//�������Ӷ���
  30.    String sql="select * from xs";
  31.    pstmt=conn.prepareStatement(sql);		//��ӡ�ɾ�����޸�
  32.    rs=pstmt.executeQuery();
  33. %>
  34.  
  35. <div class = "dv2" align = "center">
  36. 	<table class = "table">
  37. 	   <tr style = "background-color:#FF6666; height:60px; color:white;">
  38. 	      <td width = "33%">学号</td>
  39. 	      <td width = "33%">姓名</td>
  40. 	      <td>编辑</td>
  41. 	   </tr>
  42. 	<%
  43. 	   int num=1; 
  44. 	   while(rs.next()){
  45. 	   if(num%2!=0) {
  46. 	%>
  47. 	     <tr>
  48. 	        <td  style = "height:60px;">
  49. 	          <%=rs.getString("sno") %>
  50. 	        </td>
  51. 	        <td>
  52. 	          <%=rs.getString("sname") %>
  53. 	        </td>
  54. 	        <td>
  55. 	           <a class = "lik" href="mysqlupdate.jsp?sno=<%=rs.getString("sno")%>&&sname=<%=rs.getString("sname")%>">update</a>&nbsp;&nbsp;<a class = "lik" href="mysqldelete.jsp?sno=<%=rs.getString("sno")%>">delete</a>
  56. 	        </td>
  57. 	     </tr>
  58. 	<% 
  59. 	   }else {
  60. 	%>
  61. 		   <tr  style = "background-color:#FFCCCC; height:60px;"> 
  62. 	        <td>
  63. 	          <%=rs.getString("sno") %>
  64. 	        </td>
  65. 	        <td>
  66. 	          <%=rs.getString("sname") %>
  67. 	        </td>
  68. 	        <td>
  69. 	           <a class = "lik" href="mysqlupdate.jsp?sno=<%=rs.getString("sno")%>&&sname=<%=rs.getString("sname")%>">update</a>&nbsp;&nbsp;<a class = "lik" href="mysqldelete.jsp?sno=<%=rs.getString("sno")%>">delete</a>
  70. 	        </td>
  71. 	     </tr>
  72. 	 <% 
  73. 	   }
  74. 	   num++;
  75. 	  }
  76. 	%>   
  77. 	</table>
  78. 	<br><br>
  79. 	<div class = "lik2"><a class="title2" href="mysqlinsert.html">添加学生基本信息</a></div>
  80. </div>
  81. <%
  82.      rs.close();
  83.      pstmt.close();
  84.      conn.close();
  85.  %>
  86. </body>
  87. </html>

2. mysqldelete.jsp

  1. <%@ page language="java" import="java.util.*,java.sql.*" pageEncoding="utf-8"%>
  2. <html>
  3.   <head>
  4.   </head>
  5.   <body>
  6. <%
  7.    String sno=request.getParameter("sno");
  8. %>
  9. <%!   
  10.   public static final String DBDRIVER="com.mysql.jdbc.Driver";
  11.   
  12.   public static final String DBURL="jdbc:mysql://localhost:3306/test?characterEncoding=utf8";
  13.   public static final String DBUSER="root";
  14.   public static final String DBPASS="imshsyxxarsh";
  15. %>
  16. <% 
  17.    Connection conn=null;
  18.    PreparedStatement pstmt=null;
  19.    ResultSet rs=null;
  20.  
  21.    Class.forName(DBDRIVER);
  22.    conn=DriverManager.getConnection(DBURL,DBUSER,DBPASS);
  23.    String sql="delete from xs where sno=?";
  24.    pstmt=conn.prepareStatement(sql);
  25.    pstmt.setString(1,sno);
  26.    pstmt.executeUpdate();
  27. %> 
  28. <%
  29.    pstmt.close();
  30.    conn.close();
  31.    response.sendRedirect("mysqlquery.jsp");
  32. %>      
  33.   </body>
  34. </html>

3.mysqlinsert.jsp

  1. <%@ page language="java" import="java.util.*,java.sql.*" pageEncoding="utf-8"%>
  2. <body>
  3. <%
  4.    //request.setCharacterEncoding("utf-8");
  5.    String sno=request.getParameter("usernum");
  6.    String sname=request.getParameter("username");
  7.    
  8.    String sname1="章";
  9.    System.out.println(sname1);
  10.  
  11.    sname=new String(sname.getBytes("ISO-8859-1"), "gb2312");
  12.    System.out.println(sname);
  13.    
  14. %>
  15. <%!   
  16.   public static final String DBDRIVER="com.mysql.jdbc.Driver";
  17.   
  18.   public static final String DBURL="jdbc:mysql://localhost:3306/test?characterEncoding=utf-8";
  19.   public static final String DBUSER="root";
  20.   public static final String DBPASS="imshsyxxarsh";
  21. %>
  22. <% 
  23.    Connection conn=null;
  24.    PreparedStatement pstmt=null;
  25.    ResultSet rs=null;
  26.  
  27.    Class.forName(DBDRIVER);
  28.    conn=DriverManager.getConnection(DBURL,DBUSER,DBPASS);
  29.    String sql="insert into xs(sno,sname) values(?,?)";
  30.    pstmt=conn.prepareStatement(sql);
  31.    pstmt.setString(1,sno);
  32.    pstmt.setString(2,sname);
  33.    pstmt.executeUpdate();
  34. %> 
  35. <%
  36.    pstmt.close();
  37.    conn.close();
  38.    response.sendRedirect("mysqlquery.jsp");
  39. %>   
  40.   </body>

4.mysqlinsert.html

  1. <head>
  2. 	<link href = "/sy3/css/query.css" rel = "stylesheet" type = "text/css">
  3. </head>
  4. <body>
  5. <div class = "submit" align = "center">
  6.     <form action="mysqlinsert.jsp" method="post">
  7.     <table class = "table2">
  8.     	<tr height = "60px;">
  9.     		<td width = "150px" align = "right">学号 ：</td>
  10.     		<td><input class = "put" type="text" name="usernum"></td>
  11.     	</tr>
  12.     	<tr height = "60px;">
  13.     		<td  align = "right"> 姓名：</td>
  14.     		<td><input class = "put" type="text" name="username"></td>
  15.     	</tr>
  16.     	<tr height = "60px;" align = "center">
  17.     		<td colspan = "2"><input class = "sub" type="submit" value="提交 "></td>
  18.     	</tr>
  19.     </table>
  20.     </form> 
  21. </div>
  22. </body>

5.mysqlupdate.jsp

  1. <%@ page language = "java" pageEncoding = "utf-8" %>
  2. <head>
  3. 	<link href = "/sy3/css/query.css" rel = "stylesheet" type = "text/css">
  4. </head>
  5. <body>
  6. <% 
  7.    
  8.    String sname=request.getParameter("sname");
  9.    //byte b[]=sname.getBytes("ISO-8859-1");
  10.    //sname=new String(b);
  11.    sname=new String(sname.getBytes("ISO-8859-1"),"gb2312");
  12. %>  
  13. <div class = "submit" align = "center">
  14.     <form action="mysqlupdate1.jsp" method="post">
  15.     <table class = "table2">
  16.     	<tr height = "60px;">
  17.     		<td width = "150px" align = "right">学号 ：</td>
  18.     		<td><input class = "put" type="text" name="usernum" value="<%=request.getParameter("sno")%>"></td>
  19.     	</tr>
  20.     	<tr height = "60px;">
  21.     		<td  align = "right"> 姓名：</td>
  22.     		<td><input class = "put" type="text" name="username" value="<%=sname%>"></td>
  23.     	</tr>
  24.     	<tr height = "60px;" align = "center">
  25.     		<td colspan = "2"><input class = "sub" type="submit" value="提交 "></td>
  26.     	</tr>
  27.     </table>
  28.    </form>
  29. </div>
  30.   </body>
  31. </html>

6.mysqlupdate1.jsp

  1. <%@ page language="java" import="java.util.*,java.sql.*" pageEncoding="utf-8"%>
  2.  
  3. <html>
  4.   <head>    
  5.   </head>
  6.   <body>
  7. <%
  8.    request.setCharacterEncoding("utf-8"); 
  9.    String sno=request.getParameter("usernum");
  10.    String sname=request.getParameter("username");
  11.  
  12. %>
  13. <%!   
  14.   public static final String DBDRIVER="com.mysql.jdbc.Driver";
  15.   
  16.   public static final String DBURL="jdbc:mysql://localhost:3306/test?characterEncoding=utf8";
  17.   public static final String DBUSER="root";
  18.   public static final String DBPASS="imshsyxxarsh";
  19. %>
  20. <% 
  21.    Connection conn=null;
  22.    PreparedStatement pstmt=null;
  23.    ResultSet rs=null;
  24.  
  25.    Class.forName(DBDRIVER);
  26.    conn=DriverManager.getConnection(DBURL,DBUSER,DBPASS);
  27.    String sql="update xs set sname=? where sno=?";
  28.    pstmt=conn.prepareStatement(sql);
  29.    pstmt.setString(2,sno);
  30.    pstmt.setString(1,sname);
  31.    pstmt.executeUpdate();
  32. %> 
  33. <%
  34.    pstmt.close();
  35.    conn.close();
  36.    response.sendRedirect("mysqlquery.jsp");
  37. %>   <br>
  38.   </body>
  39. </html>

7.query.css

  1. @charset "UTF-8";
  2. body{
  3. 	color:#666666;
  4. }
  5. .title{
  6. 	display:block;
  7. 	width:400px;
  8. 	margin:auto;
  9. 	margin-top:80px;
  10. 	color:#666666;
  11. 	border:2px;
  12. 	font-size:40px;
  13. 	font-weight:bold;
  14. }
  15. a{
  16. 	text-decoration:none;
  17. }
  18. .lik{
  19. 	color:#993366;
  20. }
  21. .dv1{
  22. 	width:100%;
  23. 	height:120px;
  24. 	border:2px;
  25. }
  26. .dv2{
  27. 	width:100%;
  28. }
  29. .lik2{
  30. 	width:200px;
  31. 	height:35px;
  32. 	border-radius:14px;
  33. 	padding-top:5px;
  34. 	background-color:#FF6666;
  35. }
  36. .title2{
  37. 	font-size:20px;
  38. 	font-weight:blod;
  39. 	color:white;
  40. 	margin:auto;
  41. }
  42. .table{
  43. 	width:80%;
  44. 	border:1px solid #ffcece;
  45. }
  46. .submit{
  47. 	 background:#ffcece;
  48. 	 height:600px; 
  49. 	 padding-top:200px;
  50. }
  51. .put{
  52. 	width:300px;
  53. 	height: 40px;
  54. }
  55. .sub{
  56. 	border:none; 
  57. 	background:#FF6666; 
  58. 	width:70px; 
  59. 	height:30px; 
  60. 	color:white; 
  61. 	font-size:15px;
  62. }
  63. .table2{
  64. 	font-size:15px; 
  65. 	font-weight:bold; 
  66. 	align:center; 
  67. 	width:40%;
  68. }

深深记得老师的话：你就不听我讲，这能学会啦？？？那魔性的声音，我相信，他不会看的，hhhh，我偏偏要学会，能咋地，丢了老脸又何妨？

告大家一个小秘密：我们东来老师，，，还喷香水，，，，hhhhhhh

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