Could we use a URLClasLoader instead of the Classpath
Hi, I've just come across a response by Craig listing the various problems that one cafes because we often do not have control over the CLASSPATH and the lib/ext problems too.. I'm trying to write some sort of an application launcher, that accepts configuration directives via a properties file and loads applications.. Here's how a properties file looks.. className= com.objectedge.tomcat.management.ui.TomcatControllerView staticMethod=main argument1=start jarFile1=.\\lib\\stop-tomcat.jar jarFile2=.\\lib\\tomcat.jar jarFile3=.\\lib\\common\\connector_util.jar jarFile4=.\\lib\\common\\core_util.jar jarFile5=.\\lib\\common\\etomcat.jar jarFile6=.\\lib\\common\\jasper-runtime.jar jarFolder1=c:\Sample I read the properties file, asemble URLs from the JarFile and JarFilder properties, and pass the whole array to a URLCLassLoader. Then I ask the URLClassloader for what ever class is mentioned in the className property, and invoke the mentioned static method on it. Well, the above is what I've got working for Tomcat 3.3 When I try to do somthing similar for TC 4.x , I load the bootstrap.jar and the tools.jar files successfully. However I get the follwing stack trace and then it all stops. --begin partial stack trace dump--- ClassName org.apache.catalina.startup.Bootstrap // this is some info that I print for myself ClassLoader java.net.URLClassLoader // this too.. Starting service Tomcat-Standalone Apache Tomcat/4.0.1 Exception during startup processing java.lang.reflect.InvocationTargetException: java.lang.NoClassDefFoundError: org /apache/catalina/loader/Reloader at java.lang.ClassLoader.defineClass0(Native Method) at java.lang.ClassLoader.defineClass(Unknown Source) at java.security.SecureClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.access$100(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at org.apache.catalina.loader.StandardClassLoader.findClass(StandardClas sLoader.java:671) at org.apache.catalina.loader.StandardClassLoader.loadClass(StandardClas sLoader.java:1090) at org.apache.catalina.loader.StandardClassLoader.loadClass(StandardClas sLoader.java:989) at java.lang.ClassLoader.loadClassInternal(Unknown Source) at org.apache.catalina.core.StandardContext.start(StandardContext.java:3 313) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1123) --- cut off here --- I've just begun to read the VM spec, and the Language Spec, and just finished downloading the Tomcat 4 source to understand classloading in that. Could some one please tell me what's exactly happening in this stack trace ? Sriram _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Solved : ClassNotFound Exception when loading Tomcat 4.0.1 via URLClassLoader
Hi all,
I've used the following workaround to address this problem.
I've created an executable jar for my UI class, and have added the bootstrap.jar file
to the Class-Path manifest attribute. This works.
--- begin manifest fiel contents ---
Manifest-Version: 1.0
Main-Class: test.TCStart
Created-By: OESI
Class-Path: bin/bootstrap.jar bin/tools.jar
--- end manifest file contents ---
This lets me run the text.TCStart class, and load tomcat 4.0.1 and load tools.jar too.
What I'm planning to tackle next is asking the SystemClassLoader to load additional
jars, the URLs/path of which I shall read form a properties file.
Regards,
Sriram
--- Start of forwarded message ---
From: Sriram Narayanan [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Reply-To: Tomcat Developers List [EMAIL PROTECTED]
Subject: ClassNotFound Exception when loading Tomcat 4.0.1 via URLClassLoader
Date: 30/11/2001 9:24:34 AM
Hello all,
I'm trying to write a Swing based UI that'll help manage Tomcat.
Towards that end, I'm first trying to load Tomcat via a URLCLassLoader. This is so
that one can load and test different Tomcat releases, and builds, and jar combinations.
My idea is to load Tomcat via a URLCLassloader.
This thing works for Tomcat 3.3, but I'm facing the following problem with Tomcat 4.0.1
Any ideas ?
Thanks,
Sriram
--- Start of forwarded message ---
From: Sriram N [EMAIL PROTECTED]
To: Tomcat Developers List [EMAIL PROTECTED]
Reply-To: Tomcat Developers List [EMAIL PROTECTED]
Subject: ClassNotFound Exception when loading Tomcat 4.0.1 via URLClassLoader
Date: 29/11/2001 6:43:02 PM
Hi all,
I'm trying to write a java class that will load Tomcat 4.0.1 for me.
My goal is:
- Do not use the classpath. The CLASSPATH env variable's contents are clear
be me first.
- Use the URLClassLoader to get started.
This technique works with Tomcat 3.3
With Tomcat 4.0.1 however, I get a ClassNotFoundException for
org.apache.catalina.loader.Reloader which is in the same bootstrap.jar that is
used to load
org.apache.catalina.startup.Bootstrap
However, when I stick to the batch file which adds bootstrap.jar to the system
CLASSPATH, tomcat runs OK, as usual.
Could some one point me to what I'm missing or doing wrong ? Thanks.
Here's the code that I use to load Tomcat 4.0.1
-- begin code
public class TCStart{
public static void main(String args[]){
try{
System.setProperty(catalina.home,f:/tc4.0.1/);
System.setProperty(catalina.base,f:/tc4.0.1/);
System.setProperty(java.class.path,);
java.io.File file = new
java.io.File(f:/tc4.0.1/bin/bootstrap.jar);
java.net.URL[] urls = new java.net.URL[]{file.toURL()};
java.net.URLClassLoader loader = new
java.net.URLClassLoader(urls);
Class aClass =
loader.loadClass(org.apache.catalina.startup.Bootstrap);
String classLoaderName =
aClass.getClassLoader().getClass().getName();
String className = aClass.getName();
System.out.println(ClassName + className);
System.out.println(ClassLoader + classLoaderName);
//Class aClass =
Class.forName(org.apache.catalina.startup.Bootstrap);
java.lang.reflect.Method method = null;
Class[] argsClass = new Class[] { String[].class };
// get the main method for the org.apache.tomcat.shell.Startup
class
method = aClass.getMethod(main, argsClass);
Object object = null;
String filePath= -f conf/server.xml;
Object[] arguments = new Object[] { new String[] {start}};
// now invoke the main method for the
org.apache.tomcat.shell.Startup class
method.invoke(object, arguments);
}catch(Exception ex){
System.err.println(Ugh ! is all that I can say);
ex.printStackTrace(System.err);
}
}
}
-- end code ---
And here's the stack Trace that I get.
begin stack trace dump ---
ClassName org.apache.catalina.startup.Bootstrap
ClassLoader java.net.URLClassLoader
Starting service Tomcat-Standalone
Apache Tomcat/4.0.1
Exception during startup processing
java.lang.reflect.InvocationTargetException: java.lang.NoClassDefFoundError:
org
/apache/catalina/loader/Reloader
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run
ClassNotFound Exception when loading Tomcat 4.0.1 via URLClassLoader
Hello all,
I'm trying to write a Swing based UI that'll help manage Tomcat.
Towards that end, I'm first trying to load Tomcat via a URLCLassLoader. This is so
that one can load and test different Tomcat releases, and builds, and jar combinations.
My idea is to load Tomcat via a URLCLassloader.
This thing works for Tomcat 3.3, but I'm facing the following problem with Tomcat 4.0.1
Any ideas ?
Thanks,
Sriram
--- Start of forwarded message ---
From: Sriram N [EMAIL PROTECTED]
To: Tomcat Developers List [EMAIL PROTECTED]
Reply-To: Tomcat Developers List [EMAIL PROTECTED]
Subject: ClassNotFound Exception when loading Tomcat 4.0.1 via URLClassLoader
Date: 29/11/2001 6:43:02 PM
Hi all,
I'm trying to write a java class that will load Tomcat 4.0.1 for me.
My goal is:
- Do not use the classpath. The CLASSPATH env variable's contents are clear
be me first.
- Use the URLClassLoader to get started.
This technique works with Tomcat 3.3
With Tomcat 4.0.1 however, I get a ClassNotFoundException for
org.apache.catalina.loader.Reloader which is in the same bootstrap.jar that is
used to load
org.apache.catalina.startup.Bootstrap
However, when I stick to the batch file which adds bootstrap.jar to the system
CLASSPATH, tomcat runs OK, as usual.
Could some one point me to what I'm missing or doing wrong ? Thanks.
Here's the code that I use to load Tomcat 4.0.1
-- begin code
public class TCStart{
public static void main(String args[]){
try{
System.setProperty(catalina.home,f:/tc4.0.1/);
System.setProperty(catalina.base,f:/tc4.0.1/);
System.setProperty(java.class.path,);
java.io.File file = new
java.io.File(f:/tc4.0.1/bin/bootstrap.jar);
java.net.URL[] urls = new java.net.URL[]{file.toURL()};
java.net.URLClassLoader loader = new
java.net.URLClassLoader(urls);
Class aClass =
loader.loadClass(org.apache.catalina.startup.Bootstrap);
String classLoaderName =
aClass.getClassLoader().getClass().getName();
String className = aClass.getName();
System.out.println(ClassName + className);
System.out.println(ClassLoader + classLoaderName);
//Class aClass =
Class.forName(org.apache.catalina.startup.Bootstrap);
java.lang.reflect.Method method = null;
Class[] argsClass = new Class[] { String[].class };
// get the main method for the org.apache.tomcat.shell.Startup
class
method = aClass.getMethod(main, argsClass);
Object object = null;
String filePath= -f conf/server.xml;
Object[] arguments = new Object[] { new String[] {start}};
// now invoke the main method for the
org.apache.tomcat.shell.Startup class
method.invoke(object, arguments);
}catch(Exception ex){
System.err.println(Ugh ! is all that I can say);
ex.printStackTrace(System.err);
}
}
}
-- end code ---
And here's the stack Trace that I get.
begin stack trace dump ---
ClassName org.apache.catalina.startup.Bootstrap
ClassLoader java.net.URLClassLoader
Starting service Tomcat-Standalone
Apache Tomcat/4.0.1
Exception during startup processing
java.lang.reflect.InvocationTargetException: java.lang.NoClassDefFoundError:
org
/apache/catalina/loader/Reloader
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at
org.apache.catalina.loader.StandardClassLoader.findClass(StandardClas
sLoader.java:671)
at
org.apache.catalina.loader.StandardClassLoader.loadClass(StandardClas
sLoader.java:1090)
at
org.apache.catalina.loader.StandardClassLoader.loadClass(StandardClas
sLoader.java:989)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at
org.apache.catalina.core.StandardContext.start(StandardContext.java:3
313)
at
org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1123)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:612)
at
org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1123)
at
Class or Interface
Hi, I just went over to http://nagoya.apache.org/~pier/documentation/api-java/org/apache/catalina/connector/warp/Constants.html And saw that this is defined as a Class rather than as an Interface. I'd like to understand the rationale behind this. Also, if there some other place where I must ask such questions, please point it out. Thanks, Sriram _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: Tomcat and Visualage for Java 4.0
Hi, I use VaJava myself, and have written a Tomcat Test Environment too. All that I do is invoke the main method actually... However, I find that what runs within VA often does not run outside of it. Either classes do not get loaded, or response.sendRedirect needs to be used in place of request despatching. I'm aware that these problems may be due to coding problems on my part. So what I do is - Do initial testing and debuggin within VA. VA is just great for debugging. - Once the workflow is implemented, test the same code outside of VA. Sriram 13/10/2001 2:20:47 AM, Hein [EMAIL PROTECTED] wrote: Dear Tomcat dev. team, Is there a version of the product mentioned in the following posting that orks with VA Java 4.0 ? http://w6.metronet.com/~wjm/tomcat/2000/Aug/msg00664.html Greetings from an experienced (and satisfied) Tomcat user from Holland, Hein _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com
