ClassNotFoundException Error even though jar file is present in WEB-INF/lib directory

Question

I'm trying to setup tomcat server with all the common spring jars going to tomcat lib directory, since I've number of web apps using spring. However one of my web app uses spring batch with quartaz jar as well. This web app was working fine when all the jars was in app1/WEB-INF/lib directory. However when I tried to move all the common spring jars to tomcat/lib directory and spring batch and quartaz jar in app1/WEB_INF/lib, I'm getting noclassdefFound Error. Here is the stack trace

Caused by: java.lang.NoClassDefFoundError: org/quartz/ObjectAlreadyExistsException
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2389)
    at java.lang.Class.getDeclaredConstructors(Class.java:1836)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.determineCandidateConstructors(AutowiredAnnotationBeanPostProcessor.java:230)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineConstructorsFromBeanPostProcessors(AbstractAutowireCapableBeanFactory.java:972)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:945)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getSingletonFactoryBeanForTypeCheck(AbstractAutowireCapableBeanFactory.java:777)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryBean(AbstractAutowireCapableBeanFactory.java:707)
    at org.springframework.beans.factory.support.AbstractBeanFactory.isTypeMatch(AbstractBeanFactory.java:523)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doGetBeanNamesForType(DefaultListableBeanFactory.java:357)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:335)
    at org.springframework.beans.factory.BeanFactoryUtils.beanNamesForTypeIncludingAncestors(BeanFactoryUtils.java:187)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:895)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:853)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:768)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486)
    ... 60 more
Caused by: java.lang.ClassNotFoundException: org.quartz.ObjectAlreadyExistsException
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247) 

However when I copy the same jar to tomcat/lib directory it works perfectly. As for as my understanding. the order of class file search is first jdk->boot strap-> system->common->web-app lib. Hence it should search for the file. in web app/web-inf/lib directory. Do I need to add any configuration to tomcat6 or maven war plugin to specify the jar?

**EDIT**

Here is pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.kp</groupId>
    <artifactId>kp-app1</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>kp app1 Maven Webapp</name>
    <url>http://maven.apache.org</url>

    <parent>
        <groupId>com.kp.parent</groupId>
        <artifactId>kp-common</artifactId>
        <version>1.0.0.0</version>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <cxf.version>2.7.5</cxf.version>
        <spring.version>3.2.3.RELEASE</spring.version>
        <aspectj.version>1.7.3</aspectj.version>
        <jstl.version>1.2</jstl.version>
        <servlet.version>3.0-alpha-1</servlet.version>
        <spring.batch.version>2.2.1.RELEASE</spring.batch.version>
        <quartz.version>1.8.5</quartz.version>
        <skipTests>true</skipTests>
    </properties>

    <dependencies>


        <!-- Spring framework -->

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>3.0.2.RELEASE</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>aopalliance</groupId>
            <artifactId>aopalliance</artifactId>
            <version>1.0</version>
            <scope>provided</scope>
        </dependency>

        <!-- ================== -->
        <!-- AOP -->
        <!-- ================== -->

        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>${aspectj.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>${aspectj.version}</version>
            <scope>provided</scope>
        </dependency>

        <!-- ================== -->
        <!-- SPRING BATCH -->
        <!-- ================== -->
        <dependency>
            <groupId>org.springframework.batch</groupId>
            <artifactId>spring-batch-core</artifactId>
            <version>${spring.batch.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.batch</groupId>
            <artifactId>spring-batch-infrastructure</artifactId>
            <version>${spring.batch.version}</version>
        </dependency>


        <!-- Required for cache/ lazy loading -->
        <dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib-nodep</artifactId>
            <version>2.2.2</version>
        </dependency>

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.4</version>
        </dependency>

        <!-- Quartz framework -->
        <dependency>
            <groupId>org.quartz-scheduler</groupId>
            <artifactId>quartz</artifactId>
            <version>${quartz.version}</version>
        </dependency>

        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.1.1</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>




    <build>

        <finalName>kp-app1</finalName>
        <outputDirectory>${project.basedir}/target/classes</outputDirectory>
        <sourceDirectory>${project.basedir}/src/main/java</sourceDirectory>

        <pluginManagement>
            <plugins>

                <plugin>
                    <groupId>org.eclipse.m2e</groupId>
                    <artifactId>lifecycle-mapping</artifactId>
                    <version>1.0.0</version>
                    <configuration>
                        <lifecycleMappingMetadata>
                            <pluginExecutions>
                                <pluginExecution>
                                    <pluginExecutionFilter>
                                        <groupId>org.apache.maven.plugins</groupId>
                                        <artifactId>maven-dependency-plugin</artifactId>
                                        <versionRange>[2.8,)</versionRange>
                                        <goals>
                                            <goal>copy-dependencies</goal>
                                        </goals>
                                    </pluginExecutionFilter>
                                    <action>
                                        <execute />
                                    </action>
                                </pluginExecution>
                            </pluginExecutions>
                        </lifecycleMappingMetadata>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>

        <plugins>

            <!-- Tomcat 6 plugin -->
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat6-maven-plugin</artifactId>
                <configuration>
                    <url>${serverUrl}:${port}/manager</url>
                    <path>/${contextpath}</path>
                    <username>${username}</username>
                    <password>${password}</password>
                </configuration>
            </plugin>

            <!-- Maven compiler -->
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>


            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.4</version>
                <configuration>
                    <webResources>
                        <resource>
                            <directory>src/main/webapp/WEB-INF/</directory>
                            <targetPath>WEB-INF</targetPath>
                            <includes>
                                <include>web.xml</include>
                            </includes>
                            <filtering>true</filtering>
                        </resource>
                    </webResources>
                </configuration>
            </plugin>

            <!--  Copy all the provided jars-->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>2.8</version>
                <configuration>
                    <outputDirectory>${project.build.directory}/provided-jars</outputDirectory>
                    <transitive>true</transitive>
                    <includeScope>provided</includeScope>
                </configuration>
                <executions>
                    <execution>
                        <id>cop-dependencies</id>
                        <phase>prepare-package</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <!-- Create a zip of all the provided jars -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>2.4</version>
                <configuration>
                    <descriptors>
                        <descriptor>src/main/resources/assembly/zip.xml</descriptor>
                    </descriptors>
                    <finalName>nms-tomcat-jars</finalName>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id> <!-- this is used for inheritance merges -->
                        <phase>package</phase> <!-- append to the packaging phase. -->
                        <goals>
                            <goal>single</goal> <!-- goals == mojos -->
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

Child class loader can find the classes loaded in parent class loader but parent class loader could not find the classes loaded by child class loader. here the spring classes required the quartz classes for bean creation but failed, Because the quartz classes loaded by child class loader.

Answer 2

Since Application context loads the classes. When I moved Spring-context.jar,Spring-web.jar and spring-context-support.jar. It started working. As suggested by @Naveen Ramawat. context loader doesn't load the classes from web-inf/classes directory(child node). Hence when I moved the these jars to web-inf/lib child classes were able to load the parent classes from tomcat lib directory.