找不到MYSQL驱动程序类

Question

Please i'm trying to have a DB data from a jsp file, but the driver class is not found (output error), it works good when i'm executing the java class directly but it's not found when i'm calling it from the jsp file.

Here is the jsp code

<%@page import="java.util.*"%>
<%@page import="java.lang.Class"%>
<%@ page language="java" import="DAO.*"%>

<%
 try{
   List<String> names=DB.getNames();
   out.print(names);
   out.flush();
    }
 catch(Exception e)
    {
   e.printStackTrace();
    }
   %>

And basically the same in the java class when executing the main .

public static void main(String[] args){
for(Iterator it=DB.getNames().iterator(); it.hasNext();) 
    System.out.println(it.next()); 

 }

Works good from java directly but not found when called from jsp.

The error shows the problem in the db connection function an especialy in this line com.mysql.jdbc.Driver

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1892)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1735)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at DAO.DB.connect(DB.java:21)
at DAO.DB.getNames(DB.java:35)

Answer 1

This issue is being faced because, your Tomcat is unable to find this class that is being referenced in your JSP / Java code.

You need to place your MySQL Connector/J jar in your CATALINA_HOME/lib folder or in <yourApplicationWAR>/WEB-INF/lib , hoping that your DB related code is in the JSP itself. Latter is preferred over placing your Connector/J in your Tomcat (or any such similar app-server)

If the code is in your JAVA class, then you would need to put it in your IDE classpath & preferably into your CLASSPATH environment variable.