Member Avatar for hwoarang69

I set up a servlet project in eclipse and I am trying to connect a Access databasae(Ucanaccess) with it. By looking at below error, its look like I am missing jar files but if you take a look at attchement image. You will see all my jar files are in the project.

ClassNotFoundException: net.ucanaccess.jdbc.UcanaccessDriver
SQLException: No suitable driver found for jdbc:ucanaccess://C:/Users/dave/My_WorkSpace/Eclipse_Workspaces/workspace-jsp/JDBC_Database.accdb
Aug 06, 2015 7:29:23 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [ex02] in context with path [/T_02_Servlet_01] threw exception
java.lang.NullPointerException
    at ex02.doGet(ex02.java:104)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

error01.png

here is the Servlet code:

@WebServlet("/ex02")
public class ex02 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public ex02() {
        super();

        String url = "jdbc:ucanaccess://C:/Users/dave/My_WorkSpace/Eclipse_Workspaces/workspace-jsp/JDBC_Database.accdb";
        Connection con;

        try {
            Class.forName("net.ucanaccess.jdbc.UcanaccessDriver");
        } catch (java.lang.ClassNotFoundException e) {
            System.err.print("ClassNotFoundException: ");
            System.err.println(e.getMessage());
        }

        try {
            con = DriverManager.getConnection(url, "", "");
            stmt0 = con.createStatement();
        } catch (SQLException ex) {
            System.err.println("SQLException: " + ex.getMessage());
        }
    }

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
            //...
    }


    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}
Edited by hwoarang69
  • 2 Contributors
  • 1 Reply
  • 2K Views
  • 6 Hours Discussion Span
  • Latest Post Latest Post by jwenting

Dani AI

Generated

This error means Tomcat cannot see the UCanAccess driver at runtime, even though Eclipse shows the JARs on your build path. As hinted, make sure the JARs are actually packaged with the webapp. When the driver is missing, DriverManager cannot find it, and later your stmt0 (or con) ends up null, causing the NPE in doGet.

Quick fixes you can try now:

  • Put the libraries under WebContent/WEB-INF/lib (for a Dynamic Web Project). Redeploy and confirm they appear in WEB-INF/lib inside the WAR.
  • Or use Project Properties -> Deployment Assembly -> Add -> Java Build Path Entries, and add the JARs so Eclipse copies them to WEB-INF/lib on publish.
  • Or drop them in TOMCAT_HOME/lib (shared for all apps), but packaging them with the app is usually cleaner.
  • Include all UCanAccess deps: ucanaccess-*.jar, jackcess-*.jar, hsqldb-*.jar, commons-logging-*.jar, and commons-lang*. Add jackcess-encrypt if your DB is encrypted.

Also tidy up the servlet lifecycle. Do not open connections in the constructor. Load the driver in init(), and open/close connections per request:

@Override
public void init() throws ServletException {
    try {
        Class.forName("net.ucanaccess.jdbc.UcanaccessDriver");
    } catch (ClassNotFoundException e) {
        throw new UnavailableException("UCanAccess driver not on classpath");
    }
}

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {
    String url = "jdbc:ucanaccess://C:/path/to/JDBC_Database.accdb";
    try (Connection con = DriverManager.getConnection(url);
         Statement stmt = con.createStatement()) {
        // use stmt...
    } catch (SQLException e) {
        throw new ServletException(e);
    }
}

One more gotcha: if Tomcat runs as a Windows service under a different account, it may not have read access to C:/Users/dave/.... Move the .accdb to a directory the service can read, or run Tomcat under your user.

Member Avatar for jwenting

and did you actually package it in your webapplication? LEARN YOUR TOOLS.

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