JDBC — java.lang.NoClassDefFoundError: could not initialize class com.mysql.jdbc.Verbindung

Ich habe den folgenden code, der versucht, eine Verbindung zu einer remote-Datenbank. Es ist eine Ausnahme, und ich kann nicht herausfinden, warum.

    import java.util.List;
    import java.util.ArrayList;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.Statement;
    import java.sql.ResultSet;

    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpSession;

    import com.model.Bulletin;

    Connection connection = getConnection();
    Statement statement = connection.createStatement();

    private Connection getConnection() {
        Connection conn = null;
        String url = "jdbc:mysql://address/cpc";
        String userName = "user";
        String password = "password"; //Don't worry, that's not the real password.
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, userName, password);
        } catch (Exception e) {
            return null;
        }

        return conn;
    }

Kann jemand mir erklären, warum ich immer diese exception?

Uncaught exception from servlet
java.lang.reflect.InvocationTargetException
    at com.google.appengine.runtime.Request.process-6673c09727e16cea(Request.java)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:43)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:453)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:292)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:255)
    at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
    at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:211)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:211)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:90)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:192)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:510)
    at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:449)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:455)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:695)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:333)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:325)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:453)
    at java.lang.Thread.run(Thread.java:679)
Caused by: java.lang.ExceptionInInitializerError
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:283)
    at java.sql.DriverManager.getConnection(DriverManager.java:620)
    at java.sql.DriverManager.getConnection(DriverManager.java:200)
    at com.dao.BulletinDAO.getConnection(BulletinDAO.java:231)
    at com.dao.BulletinDAO.getApprovedBulletins(BulletinDAO.java:134)
    at com.action.GetApprovedBulletins.execute(GetApprovedBulletins.java:45)
    ... 74 more
Caused by: java.security.AccessControlException: access denied (java.lang.RuntimePermission modifyThreadGroup)
    at java.security.AccessControlContext.checkPermission(AccessControlContext.java:355)
    at java.security.AccessController.checkPermission(AccessController.java:567)
    at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
    at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
    at java.lang.Thread.init(Thread.java:353)
    at java.lang.Thread.<init>(Thread.java:437)
    at java.util.TimerThread.<init>(Timer.java:478)
    at java.util.Timer.<init>(Timer.java:100)
    at java.util.Timer.<init>(Timer.java:146)...(length 8258)

zeigen Sie uns Ihre imports
Ihr stack-trace macht oder Aussehen nicht die Klasse.Vorname Linie, ist das werfen der Ausnahme. Sind Sie sicher, dass es ist?
Die Meldung "an com.dao.BulletinDAO.getConnection(BulletinDAO.java:229)" maps "conn = DriverManager.getConnection(url, userName, password);". Es ist nicht der Erstellung der Verbindung.
Wo kann ich herunterladen, das jar?

InformationsquelleAutor | 2012-07-08

jdbc noclassdeffounderror

1

Dies ist fast sicher, weil Sie fehlen, ist der jdbc-Treiber-jar für MySql. Sie finden es Hier. Entpacken Sie es und fügen Sie die jar in den classpath.

Update:
Sie können nicht die Verwendung von MySQL mit GAE denn die Steckdosen sind nicht erlaubt. Das wird nie für Sie arbeiten. Sie haben alternative Persistenz-Mechanismen neben MySQL. Siehe: Kann ich eine MySQL-Datenbank mit einer App Engine-Anwendung
- Ich habe versucht, das hinzufügen der neuesten MySQL-Treiber jar, die ich finden konnte, und es hat nicht funktioniert. Ich habe meinem ursprünglichen post bearbeitet, um zu zeigen, die gesamte Fehlermeldung, ich bin jetzt immer.
- Ich mag mich irren, aber es sieht aus wie Sie mit Google app engine und ich glaube nicht, dass JDBC ist durch die it unterstützt. Werfen Sie einen Blick auf die Unterseite Ausnahme. Sie bekommen eine Erlaubnis, Ausnahme zu werfen.
- Ja, das ist auf Google Apps.
- Dies wird nicht immer Arbeit für Sie dann. Siehe meine aktualisierte Antwort.
InformationsquelleAutor jjathman

Versuchen Sie dies:

try
{   //Load driver class
    Class.forName("com.mysql.jdbc.Driver");
}
catch (java.lang.ClassNotFoundException e) {
    System.err.println("ClassNotFoundException: " +e);
}

Statt:

 try {
    //Exception thrown in next line.
        Class.forName(driver).newInstance();
        conn = DriverManager.getConnection(url, userName, password);
    } catch (Exception e) {
        return null;
    }

InformationsquelleAutor ewein

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