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Java Forum / General / January 2006error using JSP, Javabeans, and Tomcat
I'm having difficult getting JSP to work with Javabeans inside Tomcat. I've been working on this for awhile, and I have seen some examples, but all the examples I found (like "sample" included with Tomcat) explain JSP and servlets but not Javabeans. I have not been able to get a complete picture of the proper configuration, even after reading the Tomcat docs. My JSP looks like this: =================================================================== <%! String pageName = "progsoftware.com"; %> <html> <head> <title><%= pageName %></title> <jsp:useBean class="dbConnect.dbConnect" id="bean0" scope="page" /> </head> <body> <h1>Welcome to <%= pageName %></h1> </body> </html> =================================================================== Depending on what I place in the "class" attribute I get different error messages: 1) "dbConnect.dbConnect": ===================================================== org.apache.jasper.JasperException: Unable to compile class for JSP An error occurred at line: 8 in the jsp file: /learn.jsp Generated servlet error: dbConnect cannot be resolved to a type An error occurred at line: 8 in the jsp file: /learn.jsp Generated servlet error: dbConnect cannot be resolved An error occurred at line: 8 in the jsp file: /learn.jsp Generated servlet error: dbConnect cannot be resolved to a type org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:84) org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:328) org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:409) org.apache.jasper.compiler.Compiler.compile(Compiler.java:288) org.apache.jasper.compiler.Compiler.compile(Compiler.java:267) org.apache.jasper.compiler.Compiler.compile(Compiler.java:255) org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:563) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) ===================================================================== 2) "dbConnect": ==================================================================== javax.servlet.ServletException: dbConnect (wrong name: dbConnect/dbConnect) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:272) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) root cause java.lang.NoClassDefFoundError: dbConnect (wrong name: dbConnect/dbConnect) java.lang.ClassLoader.defineClass1(Native Method) java.lang.ClassLoader.defineClass(Unknown Source) java.security.SecureClassLoader.defineClass(Unknown Source) java.net.URLClassLoader.defineClass(Unknown Source) java.net.URLClassLoader.access$100(Unknown Source) java.net.URLClassLoader$1.run(Unknown Source) java.security.AccessController.doPrivileged(Native Method) java.net.URLClassLoader.findClass(Unknown Source) java.lang.ClassLoader.loadClass(Unknown Source) java.lang.ClassLoader.loadClass(Unknown Source) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1325) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1187) org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1210) org.apache.jasper.compiler.Node$UseBean.accept(Node.java:1116) org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163) org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2213) org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2219) org.apache.jasper.compiler.Node$Root.accept(Node.java:456) org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163) org.apache.jasper.compiler.Generator.generate(Generator.java:3284) org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:189) org.apache.jasper.compiler.Compiler.compile(Compiler.java:286) org.apache.jasper.compiler.Compiler.compile(Compiler.java:267) org.apache.jasper.compiler.Compiler.compile(Compiler.java:255) org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:563) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) ====================================================================== 3) "asdf" (random string): ====================================================================== org.apache.jasper.JasperException: /learn.jsp(8,1) The value for the useBean class attribute asdf is invalid. org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:39) org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:405) org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:146) org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1223) org.apache.jasper.compiler.Node$UseBean.accept(Node.java:1116) org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163) org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2213) org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2219) org.apache.jasper.compiler.Node$Root.accept(Node.java:456) org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163) org.apache.jasper.compiler.Generator.generate(Generator.java:3284) org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:189) org.apache.jasper.compiler.Compiler.compile(Compiler.java:286) org.apache.jasper.compiler.Compiler.compile(Compiler.java:267) org.apache.jasper.compiler.Compiler.compile(Compiler.java:255) org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:563) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) ======================================================================= Interestingly, sometimes when I do a reload in my browsers (Firefox and IE) one of the previous error messages are returned. This appears at random, and the error messages will interleave merely by refreshing. It appears that Tomcat inappropriately caches. My directory structure is ======================================================================= Directory of C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware 01/12/2006 01:49 PM <DIR> . 01/12/2006 01:49 PM <DIR> .. 01/12/2006 11:43 AM 317 .classpath 01/12/2006 06:29 AM 388 .project 01/12/2006 01:42 PM <DIR> .settings 01/12/2006 02:11 PM 228 learn.jsp 01/12/2006 01:42 PM <DIR> source 01/12/2006 01:42 PM <DIR> WEB-INF 01/12/2006 10:51 AM 287 web.xml 4 File(s) 1,220 bytes Directory of C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware\.settings 01/12/2006 01:42 PM <DIR> . 01/12/2006 01:42 PM <DIR> .. 01/12/2006 06:29 AM 330 org.eclipse.jdt.core.prefs 1 File(s) 330 bytes Directory of C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware\source 01/12/2006 01:42 PM <DIR> . 01/12/2006 01:42 PM <DIR> .. 01/12/2006 01:42 PM <DIR> dbConnect 0 File(s) 0 bytes Directory of C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware\source\dbConnect 01/12/2006 01:42 PM <DIR> . 01/12/2006 01:42 PM <DIR> .. 01/12/2006 12:45 PM 1,247 dbConnect.java 1 File(s) 1,247 bytes Directory of C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware\WEB-INF 01/12/2006 01:42 PM <DIR> . 01/12/2006 01:42 PM <DIR> .. 01/12/2006 01:42 PM <DIR> classes 01/12/2006 01:42 PM <DIR> lib 0 File(s) 0 bytes Directory of C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware\WEB-INF\classes 01/12/2006 01:42 PM <DIR> . 01/12/2006 01:42 PM <DIR> .. 01/12/2006 01:42 PM <DIR> dbConnect 0 File(s) 0 bytes Directory of C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware\WEB-INF\classes\dbConnect 01/12/2006 01:42 PM <DIR> . 01/12/2006 01:42 PM <DIR> .. 01/12/2006 12:45 PM 1,918 dbConnect.class 1 File(s) 1,918 bytes Directory of C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware\WEB-INF\lib 01/12/2006 01:42 PM <DIR> . 01/12/2006 01:42 PM <DIR> .. 0 File(s) 0 bytes =================================================================== Following are the contents of some relevant files dbConnect.java (the class file is in the webapps\progsoftware folder, and the java file is in a "workspace" folder outside the Tomcat hierarchy.) ====================================================================== package dbConnect; import java.sql.DriverManager; import java.sql.Connection; import java.sql.SQLException; import java.sql.ResultSet; import java.sql.Statement; import java.lang.ClassNotFoundException; public class dbConnect { private Connection con; private ResultSet rs; public dbConnect(){} //added after reading that beans require default constructors public void DBConnect(String dbName, String username, String password) throws ClassNotFoundException,SQLException { Class.forName("org.postgresql.Driver"); con = DriverManager.getConnection("jdbc:postgresql:postgres",username,password); } public void execStmt(String queryString) throws SQLException { Statement stmt = con.createStatement(); rs = stmt.executeQuery(queryString); } public void closeConnection() throws SQLException { con.close(); } public dbConnect(String dbName, String username, String password, String queryString) throws ClassNotFoundException,SQLException { DBConnect(dbName,username,password); execStmt(queryString); closeConnection(); } public dbConnect(String dbName, String username, String password) throws ClassNotFoundException,SQLException { DBConnect(dbName,username,password); } public ResultSet getResultSet() { return rs; } } =================================================================== web.xml (I'm under the impression that it only needs to be filled when running servlets, which I'm not) ======================================================================= <?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/j2ee/dtds/web-app_2_3.dtd"> <web-app> </web-app> ===================================================================== Because of its length, I'm not posting the complete contents of conf\server.xml, but I only added one line which I read was required: <Context path="C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\progsoftware" docBase="progsoftware" debug="0" reloadable="true" /> This is just before </host>. The source I was reading (http://www.onjava.com/pub/a/onjava/2001/04/19/tomcat.html?page=2) said to add the line but did not state where to place it. I'm wondering though if this is only required when using servelets. I don't think I have changed any other files. Software versions: Tomcat 5.5.12 Eclipse: 3.1.1 OS: WinXP sp 2 JDK: 1.5.0_06 You say you aren't using servlets, yet you got an error message saying: Generated servlet error: so you apparently _are_ using servlets, so you would need an entry in web.xml that instructs the server to instantiate your dbConnect class on demand (or at startup, as you prefer). My experience is with JSF, so I do those things in the JSF.xml file. Your class="dbConnect.dbConnect" value is the correct one. Rick > I'm having difficult getting JSP to work with Javabeans inside Tomcat. > I've been working on this for awhile, and I have seen some examples, [quoted text clipped - 19 lines] > </body> > </html> looks correct > =================================================================== > web.xml (I'm under the impression that it only needs to be filled when > running servlets, which I'm not) not really, but it doesn't matter > Because of its length, I'm not posting the complete contents of > conf\server.xml, but I only added one line which I read was required: > <Context path="C:\Program Files\Apache Software Foundation\Tomcat > 5.5\webapps\progsoftware" docBase="progsoftware" debug="0" > reloadable="true" /> this is probably not correct. Also, if the application is in the webapps directory it's not necessary. Read the Tomcat documentation for more information I'm not sure this is the cause of the problem, though > This is just before </host>. The source I was reading > (http://www.onjava.com/pub/a/onjava/2001/04/19/tomcat.html?page=2) said > to add the line but did not state where to place it. > I'm wondering though if this is only required when using servelets. no. This has some specific information for Tomcat to handle your web application; for example, the location of the application itself or if classes should be loaded as soon as they are put into the web application What you did looks fine. Try to reproduce the problem with a new,clean application. Or try to reinstall Tomcat Rick, Andrea, thanks for responding. I reinstalled Tomcat and everything works now. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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