Mule Custom Transformer: No class for element custom-transformer

Question

I'm trying to create a simple flow that takes a string from an HTTP endpoint, changes it using a custom Java transformer, and then sends it back to the client. Unfortunately, Mule doesn't seem to be able to find or otherwise use my custom class when I attempt to run the flow. Examples of my code are below:

MyClass.java (the custom transformer class):

package myPackage;

import org.mule.api.MuleMessage;
import org.mule.api.transformer.TransformerException;
import org.mule.transformer.AbstractMessageTransformer;

public class MyClass extends AbstractMessageTransformer {
    @Override
    public Object transformMessage(MuleMessage message, String outputEncoding) throws TransformerException {
        Object[] payload = new Object[] {"Payload has been modified"};

        message.setPayload(payload);

        return message;
    }
}

myFlow.mflow (the flow using the HTTP and custom transformer components):

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:spring="http://www.springframework.org/schema/beans" version="EE-3.4.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd">
    <flow name="myFlow1" doc:name="myFlow1">
        <http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081" doc:name="HTTP"/>
        <custom-transformer class="myPackage.MyClass" doc:name="Java"/>
    </flow>
</mule>

Error log:

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ New app 'myApp'                                          +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
INFO  2013-12-18 13:13:11,493 [main] org.mule.module.launcher.application.DefaultMuleApplication: 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Initializing app 'myApp'                                 +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
INFO  2013-12-18 13:13:11,674 [main] org.mule.lifecycle.AbstractLifecycleManager: Initialising RegistryBroker
INFO  2013-12-18 13:13:11,797 [main] org.mule.config.spring.MuleApplicationContext: Refreshing org.mule.config.spring.MuleApplicationContext@28d9a0c1: startup date [Wed Dec 18 13:13:11 GMT 2013]; root of context hierarchy
ERROR 2013-12-18 13:13:12,700 [main] org.mule.config.spring.parsers.generic.ChildDefinitionParser: could not load class: myPackage.MyClass
java.lang.ClassNotFoundException: myPackage.MyClass
    at org.mule.util.ClassUtils.loadClass(ClassUtils.java:316)
    at org.mule.util.ClassUtils.loadClass(ClassUtils.java:212)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.getBeanClassFromAttribute(AbstractMuleBeanDefinitionParser.java:382)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.getClassInternal(AbstractMuleBeanDefinitionParser.java:345)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.parseInternal(AbstractMuleBeanDefinitionParser.java:266)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.muleParse(AbstractMuleBeanDefinitionParser.java:497)
    at org.mule.config.spring.parsers.delegate.AbstractParallelDelegatingDefinitionParser.muleParse(AbstractParallelDelegatingDefinitionParser.java:44)
    at org.mule.config.spring.parsers.delegate.AbstractDelegatingDefinitionParser.parseInternal(AbstractDelegatingDefinitionParser.java:61)
    at org.springframework.beans.factory.xml.AbstractBeanDefinitionParser.parse(AbstractBeanDefinitionParser.java:59)
    at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:88)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:190)
    at org.mule.config.spring.MuleBeanDefinitionDocumentReader.parseBeanDefinitions(MuleBeanDefinitionDocumentReader.java:55)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174)
    at org.mule.config.spring.MuleApplicationContext.loadBeanDefinitions(MuleApplicationContext.java:113)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451)
    at org.mule.config.spring.SpringRegistry.doInitialise(SpringRegistry.java:89)
    at org.mule.registry.AbstractRegistry.initialise(AbstractRegistry.java:109)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.createSpringRegistry(SpringXmlConfigurationBuilder.java:119)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.doConfigure(SpringXmlConfigurationBuilder.java:73)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.config.builders.AutoConfigurationBuilder.autoConfigure(AutoConfigurationBuilder.java:101)
    at org.mule.config.builders.AutoConfigurationBuilder.doConfigure(AutoConfigurationBuilder.java:57)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.context.DefaultMuleContextFactory.createMuleContext(DefaultMuleContextFactory.java:84)
    at org.mule.module.launcher.application.DefaultMuleApplication.init(DefaultMuleApplication.java:207)
    at org.mule.module.launcher.application.ApplicationWrapper.init(ApplicationWrapper.java:64)
    at org.mule.module.launcher.DefaultMuleDeployer.deploy(DefaultMuleDeployer.java:47)
    at org.mule.tooling.server.application.ApplicationDeployer.main(ApplicationDeployer.java:127)
ERROR 2013-12-18 13:13:12,716 [main] org.mule.module.launcher.application.DefaultMuleApplication: null
java.lang.IllegalStateException: No class for element custom-transformer{name=Java}
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.getClassInternal(AbstractMuleBeanDefinitionParser.java:358)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.parseInternal(AbstractMuleBeanDefinitionParser.java:266)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.muleParse(AbstractMuleBeanDefinitionParser.java:497)
    at org.mule.config.spring.parsers.delegate.AbstractParallelDelegatingDefinitionParser.muleParse(AbstractParallelDelegatingDefinitionParser.java:44)
    at org.mule.config.spring.parsers.delegate.AbstractDelegatingDefinitionParser.parseInternal(AbstractDelegatingDefinitionParser.java:61)
    at org.springframework.beans.factory.xml.AbstractBeanDefinitionParser.parse(AbstractBeanDefinitionParser.java:59)
    at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:88)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:190)
    at org.mule.config.spring.MuleBeanDefinitionDocumentReader.parseBeanDefinitions(MuleBeanDefinitionDocumentReader.java:55)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174)
    at org.mule.config.spring.MuleApplicationContext.loadBeanDefinitions(MuleApplicationContext.java:113)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451)
    at org.mule.config.spring.SpringRegistry.doInitialise(SpringRegistry.java:89)
    at org.mule.registry.AbstractRegistry.initialise(AbstractRegistry.java:109)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.createSpringRegistry(SpringXmlConfigurationBuilder.java:119)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.doConfigure(SpringXmlConfigurationBuilder.java:73)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.config.builders.AutoConfigurationBuilder.autoConfigure(AutoConfigurationBuilder.java:101)
    at org.mule.config.builders.AutoConfigurationBuilder.doConfigure(AutoConfigurationBuilder.java:57)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.context.DefaultMuleContextFactory.createMuleContext(DefaultMuleContextFactory.java:84)
    at org.mule.module.launcher.application.DefaultMuleApplication.init(DefaultMuleApplication.java:207)
    at org.mule.module.launcher.application.ApplicationWrapper.init(ApplicationWrapper.java:64)
    at org.mule.module.launcher.DefaultMuleDeployer.deploy(DefaultMuleDeployer.java:47)
    at org.mule.tooling.server.application.ApplicationDeployer.main(ApplicationDeployer.java:127)
INFO  2013-12-18 13:13:12,717 [main] org.mule.module.launcher.application.DefaultMuleApplication: App 'myApp' never started, nothing to dispose of
Exception in thread "main" org.mule.module.launcher.DeploymentInitException: IllegalStateException: No class for element custom-transformer{name=Java}
    at org.mule.module.launcher.application.DefaultMuleApplication.init(DefaultMuleApplication.java:219)
    at org.mule.module.launcher.application.ApplicationWrapper.init(ApplicationWrapper.java:64)
    at org.mule.module.launcher.DefaultMuleDeployer.deploy(DefaultMuleDeployer.java:47)
    at org.mule.tooling.server.application.ApplicationDeployer.main(ApplicationDeployer.java:127)
Caused by: org.mule.api.config.ConfigurationException: Unexpected exception parsing XML document from URL [file:/C:/mulestudio-3.5/workspace/.mule/apps/myApp/myApp.xml]; nested exception is java.lang.IllegalStateException: No class for element custom-transformer{name=Java} (org.mule.api.lifecycle.InitialisationException) (org.mule.api.config.ConfigurationException)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:52)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.context.DefaultMuleContextFactory.createMuleContext(DefaultMuleContextFactory.java:84)
    at org.mule.module.launcher.application.DefaultMuleApplication.init(DefaultMuleApplication.java:207)
    ... 3 more
Caused by: org.mule.api.config.ConfigurationException: Unexpected exception parsing XML document from URL [file:/C:/mulestudio-3.5/workspace/.mule/apps/myApp/myApp.xml]; nested exception is java.lang.IllegalStateException: No class for element custom-transformer{name=Java} (org.mule.api.lifecycle.InitialisationException)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:52)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.config.builders.AutoConfigurationBuilder.autoConfigure(AutoConfigurationBuilder.java:101)
    at org.mule.config.builders.AutoConfigurationBuilder.doConfigure(AutoConfigurationBuilder.java:57)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    ... 6 more
Caused by: org.mule.api.lifecycle.InitialisationException: Unexpected exception parsing XML document from URL [file:/C:/mulestudio-3.5/workspace/.mule/apps/myApp/myApp.xml]; nested exception is java.lang.IllegalStateException: No class for element custom-transformer{name=Java}
    at org.mule.registry.AbstractRegistry.initialise(AbstractRegistry.java:117)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.createSpringRegistry(SpringXmlConfigurationBuilder.java:119)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.doConfigure(SpringXmlConfigurationBuilder.java:73)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    ... 10 more
Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from URL [file:/C:/mulestudio-3.5/workspace/.mule/apps/myApp/myApp.xml]; nested exception is java.lang.IllegalStateException: No class for element custom-transformer{name=Java}
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:412)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174)
    at org.mule.config.spring.MuleApplicationContext.loadBeanDefinitions(MuleApplicationContext.java:113)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451)
    at org.mule.config.spring.SpringRegistry.doInitialise(SpringRegistry.java:89)
    at org.mule.registry.AbstractRegistry.initialise(AbstractRegistry.java:109)
    ... 13 more
Caused by: java.lang.IllegalStateException: No class for element custom-transformer{name=Java}
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.getClassInternal(AbstractMuleBeanDefinitionParser.java:358)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.parseInternal(AbstractMuleBeanDefinitionParser.java:266)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.muleParse(AbstractMuleBeanDefinitionParser.java:497)
    at org.mule.config.spring.parsers.delegate.AbstractParallelDelegatingDefinitionParser.muleParse(AbstractParallelDelegatingDefinitionParser.java:44)
    at org.mule.config.spring.parsers.delegate.AbstractDelegatingDefinitionParser.parseInternal(AbstractDelegatingDefinitionParser.java:61)
    at org.springframework.beans.factory.xml.AbstractBeanDefinitionParser.parse(AbstractBeanDefinitionParser.java:59)
    at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:88)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:190)
    at org.mule.config.spring.MuleBeanDefinitionDocumentReader.parseBeanDefinitions(MuleBeanDefinitionDocumentReader.java:55)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
    ... 22 more

.classpath contents (untouched, this is as it was generated by MuleStudio):

<?xml version="1.0" encoding="UTF-8"?>
<classpath>
    <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7"/>
    <classpathentry exported="true" kind="con" path="MULE_RUNTIME"/>
    <classpathentry kind="src" path="src/main/java"/>
    <classpathentry kind="src" path="src/main/resources"/>
    <classpathentry kind="src" output="target/test-classes" path="src/test/java"/>
    <classpathentry kind="src" output="target/test-classes" path="src/test/resources"/>
    <classpathentry kind="output" path="target/classes"/>
</classpath>

MyClass.java is located at C:\\mulestudio-3.5\\workspace\\myApp\\src\\main\\java\\myPackage\\MyClass.java (where MuleStudio automatically put it), and all files in src\\main are included in the BuildPath settings.

As far as I can tell, I've done everything I need to in order to use the custom transformer. Evidently, I've missed something out. What can I do to get my custom transformer working?

Answer 1

如果您在Mule Studio中创建新的Java类，则必须停止并开始获取更改，重新部署不会获得新的.java，或者至少是我发生的。

Answer 2

Check the case you are using for the class name: public class myClass (lower m) and <custom-transformer class="myPackage.MyClass" (upper M).

You need to change your transformer class declaration to "myPackage.myClass".

Answer 3

I fixed this problem by rolling back to MuleStudio 3.4.0. It would therefore appear to be an issue with my installation of 3.4.1.

Answer 4

Your code is not compiling by the Studio hence the error. Many times working with newly created projects (from Import...) I catch myself struggling to find why my code is not compiling and Studio is spitting weird errors. First thing for me to check is "Java Build Path" - right click on your project. Make sure there is no red X's in you "Library" or "Source" caused by a missing jar or folder.