使用jndi实现数据库连接。
<%@page import="java.sql.Connection"%>
<%@page import="javax.sql.DataSource"%>
<%@page import="javax.naming.*"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
//2.通过ctx到配置文件中查找指定的名称
DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/mysql");
//3.通过ds得到连接对象
Connection conn = ds.getConnection();
//4.对连接判断
if (conn != null) {
out.println("数据库连接成功!");
}
%>
1. 下载指定的数据库驱动jar包，放入容器tomcat lib中。
2. 开始配置tomcat配置文件: conf--->context.xml
3. 在context.xml中要配置一个资源的标签。
这三步没有问题 主要是通过ds得到连接对象老是出错
HTTP Status 500 - An exception occurred processing JSP page /jndi/testjndi2.jsp at line 39
type Exception report
message An exception occurred processing JSP page /jndi/testjndi2.jsp at line 39
description The server encountered an internal error that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: An exception occurred processing JSP page /jndi/testjndi2.jsp at line 39
36: DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/mysql");
37:
38: //3.閫氳繃ds寰楀埌杩炴帴瀵硅薄
39: Connection conn = ds.getConnection();
40:
41: //4.瀵硅繛鎺ュ垽鏂�
42: if (conn != null) {
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:579)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:461)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause
javax.servlet.ServletException: java.sql.SQLException: Cannot create JDBC driver of class '' for connect URL 'null'
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:909)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:838)
org.apache.jsp.jndi.testjndi2_jsp._jspService(testjndi2_jsp.java:183)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause
java.sql.SQLException: Cannot create JDBC driver of class '' for connect URL 'null'
org.apache.tomcat.dbcp.dbcp2.BasicDataSource.createConnectionFactory(BasicDataSource.java:2184)
org.apache.tomcat.dbcp.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:2056)
org.apache.tomcat.dbcp.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1532)
org.apache.jsp.jndi.testjndi2_jsp._jspService(testjndi2_jsp.java:159)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause
java.sql.SQLException: No suitable driver
java.sql.DriverManager.getDriver(Unknown Source)
org.apache.tomcat.dbcp.dbcp2.BasicDataSource.createConnectionFactory(BasicDataSource.java:2168)
org.apache.tomcat.dbcp.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:2056)
org.apache.tomcat.dbcp.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1532)
org.apache.jsp.jndi.testjndi2_jsp._jspService(testjndi2_jsp.java:159)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
note The full stack trace of the root cause is available in the Apache Tomcat/8.0.49 logs.
可能是server.xml文件配置问题，具体参考server.xml和server.xml
错误信息提示的已经很明显 driverClassName 和 url 都没有配置 driverClassName配置的应该是空字符‘’，url应该是直接就没有配置，所以提示null
你检查下配置信息吧 看看context.xml 中的resouce配置了没有
javax.servlet.ServletException: java.sql.SQLException: Cannot create JDBC driver of class '' for connect URL 'null'
写的很清楚了 comp/env/jdbc/mysql.xml没有url
我记得是tomcat版本不同，tomcat9只需要在项目目录下配置一个server.xml即可