Cannot create JDBC driver of class ' for connect URL ' null '

Today, tomcat5.528. Configure the data source connection pool, configure it on the Tomcat admin interface, write a Serverlet test, and report a cannot create JDBC driver of class ' for connect URL ' null ' ERROR,

Org.apache.tomcat.dbcp.dbcp.SQLNestedException:Cannot Create JDBC driver of class ' for connect URL ' null '
At Org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource (basicdatasource.java:1150)
At Org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection (basicdatasource.java:880)
At Test. Testserverlet.service (testserverlet.java:29)
At Javax.servlet.http.HttpServlet.service (httpservlet.java:729)
At Org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (applicationfilterchain.java:269)
At Org.apache.catalina.core.ApplicationFilterChain.doFilter (applicationfilterchain.java:188)
At Org.apache.catalina.core.StandardWrapperValve.invoke (standardwrappervalve.java:213)
At Org.apache.catalina.core.StandardContextValve.invoke (standardcontextvalve.java:172)
At Org.apache.catalina.core.StandardHostValve.invoke (standardhostvalve.java:127)
At Org.apache.catalina.valves.ErrorReportValve.invoke (errorreportvalve.java:117)
At Org.apache.catalina.core.StandardEngineValve.invoke (standardenginevalve.java:108)
At Org.apache.catalina.connector.CoyoteAdapter.service (coyoteadapter.java:174)
At Org.apache.coyote.http11.Http11Processor.process (http11processor.java:873)
At Org.apache.coyote.http11.http11baseprotocol$http11connectionhandler.processconnection ( http11baseprotocol.java:665)
At Org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket (pooltcpendpoint.java:528)
At Org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt (leaderfollowerworkerthread.java:81)
At Org.apache.tomcat.util.threads.threadpool$controlrunnable.run (threadpool.java:689)
At Java.lang.Thread.run (thread.java:595)
caused by:java.sql.SQLException:No suitable driver
At Java.sql.DriverManager.getDriver (drivermanager.java:243)
At Org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource (basicdatasource.java:1143)
... More

, in a search on the internet, all said 5.5 with errors, and some said that the version did not appear this wrong, I feel sure is where the configuration is not correct, not the version is not supported, Java.sql.SQLException:No suitable driver
See this paragraph still wrong to think is the driver version of MySQL is wrong, and another one or the same, and later found on the internet a person said, "and then in the WebApp context.xml add" Here configuration, I looked for a bit context.xml this file open a look

<resource
Auth= "Container"
description= "Dmst"
Name= "Jdbc/dmst"
Type= "Javax.sql.DataSource"
Driverclassname= ""
/>

My gut tells me the problem is here. Driverclassname= "" Here is not "", the error is not to say cannot create JDBC driver of class ' for connect URL ' null ';d riverclass is empty, The URL is null; so I put driverclassname= "Com.mysql.jdbc.Driver"
Url= "JDBC:MYSQL://LOCALHOST:3306/QXXT?USEUNICODE=TRUE&AMP;CHARACTERENCODING=GBK" These two words plus go, restart, haha

Visit Serverlet, haha, the wrong finally did not, but still wrong is said to prevent me to connect to the database, a look at it is the user name does not, and then add the user name password, all OK

All right, I'm going to send out the entire code.

%tomcat_home%/conf/server.xml

<resource name= "Jdbc/dmst" type= "Javax.sql.DataSource" driverclassname= "Com.mysql.jdbc.Driver" password= "root" Maxidle= "2" maxwait= "username=" root "url=" jdbc:mysql://localhost:3306/qxxt?useunicode=true& CHARACTERENCODING=GBK "maxactive=" 4 "/>

The key to the issue, the other will not send it.

Web. XML for the WebApp project

<?xml version= "1.0" encoding= "UTF-8"?> <web-app version= "2.5" xmlns= "Http://java.sun.com/xml/ns/javaee" Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation= "Http://java.sun.com/xml/ns/javaee http ://java.sun.com/xml/ns/javaee/web-app_2_5.xsd "> <servlet> <description>this is the description of my Java EE component</description> <display-name>this is the display name of my EE component</display-name > <servlet-name>TreeServerlet</servlet-name> <servlet-class> Com.pmsm.serverlet.treeserverlet</servlet-class> </servlet> <servlet> <description>this is The description of my EE component</description> <display-name>this is the display name of my my EE component </display-name> <servlet-name>TestServerlet</servlet-name> <servlet-class>test. testserverlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>treeserverlet </servleT-name> <url-pattern>/servlet/treeServerlet</url-pattern> </servlet-mapping> < Servlet-mapping> <servlet-name>TestServerlet</servlet-name> <url-pattern>/servlet/ testserverlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file> index.jsp</welcome-file> </welcome-file-list> <resource-ref> <description>dmst</ Description> <res-ref-name>jdbc/dmst</res-ref-name> <res-type>javax.sql.datasource</ res-type> <res-auth>Container</res-auth> </resource-ref> </web-app>

My test serverlet here is Testserverlet.

Testserverlet.java

Package test; Import java.io.IOException; Import Java.io.PrintWriter; Import java.sql.Connection; Import java.sql.PreparedStatement; Import Java.sql.ResultSet; Import java.sql.SQLException; Import java.sql.Statement; Import Javax.naming.InitialContext; Import javax.naming.NamingException; Import javax.servlet.ServletException; Import Javax.servlet.http.HttpServlet; Import Javax.servlet.http.HttpServletRequest; Import Javax.servlet.http.HttpServletResponse; Import Javax.sql.DataSource; public class Testserverlet extends HttpServlet {@Override protected void service (HttpServletRequest arg0, Httpservletres Ponse arg1) throws Servletexception, IOException {DataSource ds = null; try {initialcontext ctx = new InitialContext (); ds = (DataSource) ctx.lookup ("Java:comp/env/jdbc/dmst"); Connection conn = Ds.getconnection (); PreparedStatement ps=conn.preparestatement ("SELECT * from Sm_user"); ResultSet Rs=ps.executequery (); while (Rs.next ()) {System.out.println (rs.getstring (1) + "," +rs.getstring (2)); } rs.close (); Ps.close (); Conn.close (); } catch (Namingexception e) {//Todo auto-generated catch Block E.printstacktrace ()} catch (SQLException e) {//Todo A Uto-generated Catch block E.printstacktrace (); } } }

Key areas:

webapps/Project Name/meta-inf/context.xml

<?xml version= "1.0" encoding= "UTF-8"?> <Context> <listener classname= " Org.apache.catalina.startup.TldConfig "/> <listener classname=" Org.apache.catalina.startup.TldConfig "/> <listener classname= "Org.apache.catalina.startup.TldConfig"/> <listener classname= " Org.apache.catalina.startup.TldConfig "/> <resource auth=" Container "description=" Dmst "name=" Jdbc/dmst " password= "root" username= "root" type= "Javax.sql.DataSource" driverclassname= "Com.mysql.jdbc.Driver" url= "JDBC: MYSQL://LOCALHOST:3306/QXXT?USEUNICODE=TRUE&CHARACTERENCODING=GBK "</Context>

OK test go, everything's OK.