使用eclipse制作 jsp，可是数据库连接总是失败

[王长伟]

<%@page import="java.sql.*"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/zkz";
String username = "root";
String password = "rsj50177546";
conn = DriverManager.getConnection(url, username, password);
request.setCharacterEncoding("utf-8");
String name = request.getParameter("name");
String pwd = request.getParameter("sfzh");
String sql = "SELECT *FROM ksxx WHERE name ='" + name + "'AND pwd = '" + pwd + "'";
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
if (rs.next()) {
response.sendRedirect("./login_success.jsp");
}else{
response.sendRedirect("./index.jsp");
}
%>

mysql 8数据库

错误提示：


异常报告

消息 在 [12] 行处理 [/logincheck.jsp] 时发生异常

描述 服务器遇到一个意外的情况，阻止它完成请求。

Exception
org.apache.jasper.JasperException: 在 [12] 行处理 [/logincheck.jsp] 时发生异常

9: String url = "jdbc:mysql://localhost:3306/zkz";
10: String username = "root";
11: String password = "abcdefg";
12: conn = DriverManager.getConnection(url, username, password);
13: request.setCharacterEncoding("utf-8");
14: String name = request.getParameter("name");
15: String pwd = request.getParameter("sfzh");


Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:617)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:499)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


Root Cause
javax.servlet.ServletException: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:909)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:838)
org.apache.jsp.logincheck_jsp._jspService(logincheck_jsp.java:145)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


Root Cause
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
com.mysql.jdbc.Util.getInstance(Util.java:387)
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:917)
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:896)
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:885)
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2330)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2083)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
java.sql.DriverManager.getConnection(Unknown Source)
java.sql.DriverManager.getConnection(Unknown Source)
org.apache.jsp.logincheck_jsp._jspService(logincheck_jsp.java:121)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


Root Cause
java.lang.NullPointerException
com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2997)
com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1936)
com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1865)
com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1228)
com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)
com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2284)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2083)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
java.sql.DriverManager.getConnection(Unknown Source)
java.sql.DriverManager.getConnection(Unknown Source)
org.apache.jsp.logincheck_jsp._jspService(logincheck_jsp.java:121)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


):注意 主要问题的全部 stack 信息可以在 server logs 里查看

[王长伟]

嗯，我再试试其他方法，谢谢大家的帮助。

[王长伟]

主要配置如下所示：

[maradona1984]

com.mysql.jdbc.ConnectionImpl.getServerCharset 这个地方报空指针了,看这方法名是获取server 的charset,也就是字符集,可以猜测下跟url上没有定义字符集有关,url改成试试jdbc:mysql://localhost:3306/zkz?useUnicode=true&characterEncoding=utf-8

[王长伟]

问题已经解决了，是建表时候表名称与数据访问名称不符造成的，谢谢各位朋友的帮助。刚开始学习JAVA和MYSQL数据库，过程非常圪坷，慢慢走吧。

[大梦不觉、]

javax.servlet.ServletException: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. mysql jar包版本问题，https://blog.csdn.net/weixin_41903771/article/details/85219221。

[CS_草祭先生]

大部分连接错误都是数据库配置问题，无论是手动敲代码还是复制过来的，都认真检查一下配置。 还有，建议楼主不要在jsp直接调用数据库。