Cannot run Spring application: BeanDefinitionParsingException

When you try to run Spring based application you can see the exception

org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Unable to locate Spring NamespaceHandler for XML schema namespace

The problem may be caused by not having all neccessary Spring jars or by jar conflicts.

First of all check that you have all jars you need. Here is the list of possible jars with explanations for Spring 3.0.5 (the original of this list of dependencies is Spring Blog):

<!-- Shared version number properties -->
<properties>
    <org.springframework.version>3.0.5.RELEASE</org.springframework.version>
</properties>
 
<!--
    Core utilities used by other modules.
    Define this if you use Spring Utility APIs (org.springframework.core.*/org.springframework.util.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-core</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Expression Language (depends on spring-core)
    Define this if you use Spring Expression APIs (org.springframework.expression.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-expression</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Bean Factory and JavaBeans utilities (depends on spring-core)
    Define this if you use Spring Bean APIs (org.springframework.beans.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-beans</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Aspect Oriented Programming (AOP) Framework (depends on spring-core, spring-beans)
    Define this if you use Spring AOP APIs (org.springframework.aop.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-aop</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Application Context (depends on spring-core, spring-expression, spring-aop, spring-beans)
    This is the central artifact for Spring's Dependency Injection Container and is generally always defined
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-context</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Various Application Context utilities, including EhCache, JavaMail, Quartz, and Freemarker integration
    Define this if you need any of these integrations
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-context-support</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Transaction Management Abstraction (depends on spring-core, spring-beans, spring-aop, spring-context)
    Define this if you use Spring Transactions or DAO Exception Hierarchy
    (org.springframework.transaction.*/org.springframework.dao.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-tx</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    JDBC Data Access Library (depends on spring-core, spring-beans, spring-context, spring-tx)
    Define this if you use Spring's JdbcTemplate API (org.springframework.jdbc.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-jdbc</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Object-to-Relation-Mapping (ORM) integration with Hibernate, JPA, and iBatis.
    (depends on spring-core, spring-beans, spring-context, spring-tx)
    Define this if you need ORM (org.springframework.orm.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-orm</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Object-to-XML Mapping (OXM) abstraction and integration with JAXB, JiBX, Castor, XStream, and XML Beans.
    (depends on spring-core, spring-beans, spring-context)
    Define this if you need OXM (org.springframework.oxm.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-oxm</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Web application development utilities applicable to both Servlet and Portlet Environments
    (depends on spring-core, spring-beans, spring-context)
    Define this if you use Spring MVC, or wish to use Struts, JSF, or another web framework with Spring (org.springframework.web.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-web</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Spring MVC for Servlet Environments (depends on spring-core, spring-beans, spring-context, spring-web)
    Define this if you use Spring MVC with a Servlet Container such as Apache Tomcat (org.springframework.web.servlet.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-webmvc</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Spring MVC for Portlet Environments (depends on spring-core, spring-beans, spring-context, spring-web)
    Define this if you use Spring MVC with a Portlet Container (org.springframework.web.portlet.*)
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-webmvc-portlet</artifactId>
  <version>${org.springframework.version}</version>
</dependency>
 
<!--
    Support for testing Spring applications with tools such as JUnit and TestNG
    This artifact is generally always defined with a 'test' scope for the integration testing framework and unit testing stubs
-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-test</artifactId>
  <version>${org.springframework.version}</version>
  <scope>test</scope>
</dependency>

If this does not help then try Maven Shade plugin to solve the most probable conflicts:

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-shade-plugin</artifactId>
 <version>1.4</version>
 <executions>
  <execution>
   <phase>package</phase>
   <goals>
    <goal>shade</goal>
   </goals>
   <configuration>
    <transformers>
     <transformer
      implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
      <resource>META-INF/spring.handlers</resource>
     </transformer>
     <transformer
      implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
      <resource>META-INF/spring.schemas</resource>
     </transformer>
    </transformers>
   </configuration>
  </execution>
 </executions>
</plugin>

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Work with annotations in Spring Framework

Annotations are a very useful feature in Java programming language and if you use Spring Framework than it can be also very easy to create annotation processor.

I expect you to be familiar with basics of annotations (read here). In this tutorial we'll create annotation for SLF4J. Here is the annotation code:

package uay.log;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Log {

}

Now let's create annotation processor using Spring Framework capabilities:

package uay.log;

import java.lang.reflect.Field;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.FieldCallback;

@Component
public class LogProcessor implements BeanPostProcessor {
 public Object postProcessAfterInitialization(Object bean, String beanName)
            throws BeansException {
        return bean;
    }

    public Object postProcessBeforeInitialization(final Object bean, String beanName)
            throws BeansException {
        ReflectionUtils.doWithFields(bean.getClass(), new FieldCallback() {
            public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException {
                if (field.getAnnotation(Log.class) != null) {
                    Logger log = LoggerFactory.getLogger(bean.getClass());
                    field.setAccessible(true);
                    field.set(bean, log);
                    field.setAccessible(false);
                }
            }
        });
        return bean;
    }
}

And it's that easy. Now we can use this annotation in our code:

@Log
Logger log;

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