新手关于jsp页面连接数据库的问题

Question

小弟想用jsp文件输入数据到mysql数据库中
这是代码
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ page import="com.mysql.jdbc.*,java.sql.Connection, java.sql.DriverManager,java.sql.PreparedStatement,java.sql.ResultSet " %>

<%
Class.forName("com.mysql.cj.jdbc.Driver"); //加载驱动
Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC&useSSL=true","root","123456");//创建连接

String username = request.getParameter("user") ;
String password = request.getParameter("password") ;
String sql = "insert into users(username , password) values('"+username+"','"+password+"')";
out.print("

"+password+"

");
PreparedStatement user = connection.preparedStatement(sql);
user.executeUpdate();
%>


这是报错信息
An error occurred at line: [13] in the jsp file: [/zhuce.jsp]
connection cannot be resolved
10: String password = request.getParameter("password") ;
11: String sql = "insert into users(username , password) values('"+username+"','"+password+"')";
12: out.print("

"+password+"

");
13: PreparedStatement user = connection.preparedStatement(sql);
14: user.executeUpdate();
15: %>
16:

Answer 1

给你一个例子 照这做 不过现在都用springmvc+mybaits+spring 用框架了 有什么问题联系我

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

QQ登录页面

账户:

密码:

验证码

登录
注册

//实现注册功能

<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
request.setCharacterEncoding("utf-8");
String name = request.getParameter("name");
String password = request.getParameter("password");
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql:///mysql_01";
String usename = "root";
String usepasword ="root";
Connection conn = DriverManager.getConnection(url , usename , usepasword);
String sql ="insert into worker values(null,?, ?)";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1,name);
ps.setString(2,password);
ps.executeUpdate();
conn.close();
response.sendRedirect("list.jsp");
%>

//从数据库中获取所有用户数据

<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

数据列表

">删除

">修改

返回主页面

//实现对数据的删除功能

<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String id =request.getParameter("name");
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql:///mysql_01";
String usename = "root";
String usepassword ="root";
Connection conn = DriverManager.getConnection(url,usename , usepassword);
String sql = "delete from worker where id="+id;
PreparedStatement ps = conn.prepareStatement(sql);

ps.executeUpdate();
conn.close();
response.sendRedirect("list.jsp");
%>

//数据库实现对要修改的数据的查询

<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.net.ConnectException"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
request.setCharacterEncoding("utf-8");
String id = request.getParameter("id");
String password = request.getParameter("password");
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql:///mysql_01";
String usename ="root";
String usepassword ="root";
Connection conn = DriverManager.getConnection(url,usename,usepassword);
String sql = "update worker set password=? where id=?";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1,password);
ps.setInt(2,Integer.parseInt(id));
ps.executeUpdate();
conn.close();
response.sendRedirect("list.jsp");
%>

//找到数据库中对应的要修改的数据，并对其进行修改

<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%
request.setCharacterEncoding("utf-8");
String id = request.getParameter("name");
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql:///mysql_01";
String usename ="root";
String usepassword ="root";
Connection conn = DriverManager.getConnection(url,usename , usepassword);
String sql ="select * from worker where id=?";
PreparedStatement ps = conn.prepareStatement(sql);
//将字符串的id转换成int型的id
ps.setInt(1, Integer.parseInt(id));
ResultSet rs= ps.executeQuery();
if(rs.next()){
%>

">

密码:">
修改

<%
}
%>

//登录功能实现从前端获取的数据与数据库的数据进行对比

<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%@page pageEncoding="utf-8" %>
<%
String name = request.getParameter("name");
String password = request.getParameter("password");
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/mysql_01";
String servername = "root";
String serverpassword = "root";
Connection conn = DriverManager.getConnection(url , servername , serverpassword);
String sql = "select * from worker";
PreparedStatement ps = conn.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
boolean flag = false;
while(rs.next()){
if(name!=null&&(rs.getString("name")).equals(name)){
if(password!=null&&(rs.getString("password")).equals(password)){
flag = true ;
break;
}else{
flag = false;
}
}else{
flag = false;
}
}

//对flag进行判断
if(flag){

%>
<br> window.location=&quot;login.jsp&quot;;<br>
<%
}else{
%>
<br> window.location=&quot;Client.jsp&quot;;<br>
<%
}
%>

//跳转登录成功页面

<%@page pageEncoding="utf-8" %>
登录成功

Answer 2

Class.forName("com.mysql.cj.jdbc.Driver");
我弄的都是com.mysql.jdbc.Driver
是版本不一样吗
preparestatement ps
直接ps.setstring（插入位置，插入数据）；
conn为null

Answer 3

String sql = "insert into users(username , password) values('"+username+"','"+password+"')"; 有问题

这样改
String sql = "insert into users(username , password) values("'+username',"+",'password'"+")";

Answer 4

不好意思 说错了 是连接串有问题
Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC&useSSL=true","root","123456");//创建连接

Answer 5

6、MySQL数据库
Class.forName("org.gjt.mm.mysql.Driver").newInstance();
String url ="jdbc:mysql://localhost/myDB?user=soft&password=soft1234&useUnicod
e=true&characterEncoding=8859_1"
//myDB为数据库名
Connection conn= DriverManager.getConnection(url);

Answer 6

报错信息提示是数据库连接的问题，无法正常连接
Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC&useSSL=true","root","123456");//创建连接
你把 ？后面的设置信息去掉看看 （感觉不是这个问题，试试），
还有就是账号和密码确定无误吗？ 注：直接root-123456进入数据库成功吗？

Answer 7

这样试试 Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test","root","123456");

Answer 8

Class.forName("com.mysql.jdbc.Driver"); 用这个