Running a Spring web application

In this recipe, we will use the Spring web application from the previous recipe. We will compile it with Maven and run it with Tomcat.

How to do it…

Here are the steps to compile and run a Spring web application:

1. In pom.xml, add this boilerplate code under the project XML node. It will allow Maven to generate .war files without requiring a web.xml file:

   <build>
       <finalName>springwebapp</finalName>
     <plugins>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-war-plugin</artifactId>
         <version>2.5</version>
         <configuration>
           <failOnMissingWebXml>false</failOnMissingWebXml>
         </configuration>
       </plugin>
     </plugins>
   </build>

2. In Eclipse, in the left-hand side pane Package Explorer, select the springwebapp project folder. In the Run menu, select Run and choose Maven install or you can execute mvn clean install in a terminal at the root of the project folder. In both cases, a target folder will be generated with the springwebapp.war file in it.
3. Copy the target/springwebapp.war file to Tomcat's webapps folder.
4. Launch Tomcat.
5. In a web browser, go to http://localhost:8080/springwebapp/hi to check whether it's working.
   

How it works…

In pom.xml the boilerplate code prevents Maven from throwing an error because there's no web.xml file. A web.xml file was required in Java web applications; however, since Servlet specification 3.0 (implemented in Tomcat 7 and higher versions), it's not required anymore.

There's more…

On Mac OS and Linux, you can create a symbolic link in Tomcat's webapps folder pointing to the .war file in your project folder. For example:

ln -s ~/eclipse_workspace/spring_webapp/target/springwebapp.war ~/bin/apache-tomcat/webapps/springwebapp.war

So, when the.war file is updated in your project folder, Tomcat will detect that it has been modified and will reload the application automatically.