Implementing Tomcat Custom Valve

I am trying to implement a custom valve in Tomcat, say MyValve which extends BaseValve. I created a jar of the project and added it into the Tomcat\lib开发者_StackOverflow folder.

The next step is of configuring the server.xml or context.xml. I tried both. But my valve class is not getting detected.

Could someone please let me know the steps to create a valve and use it.

Thanks

The question is on steps required to create a custom valve and use it. So let me explain it step by step for someone else also to take advantage of it. For my example, I will use a Java Maven Project. (Git Project)

Step 1: Open a new or existing maven project (you can also clone from the above repo).

Step 2: Add the following dependency to the pom.xml file.

<dependency>
            <groupId>org.apache.tomcat</groupId>
            <artifactId>tomcat-catalina</artifactId>
            <version>7.0.85</version>
            <scope>provided</scope>
</dependency>

Step 3: Under src/main/java path, create a package and create a new Java Class: TomcatValve.java (could be any name). Extend this class by ValueBase class.

Step 4: With this, you will have to implement its invoke method. The entire class would look something similar to this:

import java.io.IOException;
import java.util.Enumeration;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.valves.ValveBase;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;

/**
 * @author Keet Sugathadasa
 */
public class TomcatValve extends ValveBase {
    private static final Logger logger = Logger.getLogger(TomcatValve.class.getName());

    public void invoke(Request request, Response response) throws IOException, ServletException {
        HttpServletRequest httpServletRequest = request.getRequest();

        Enumeration<String> headerNames = httpServletRequest.getHeaderNames();

        logger.info("Receiving request");

        while (headerNames.hasMoreElements()) {
            String header = headerNames.nextElement();
            logger.log(Level.INFO, "Header --> {0} Value --> {1}", new Object[]{header, httpServletRequest.getHeader(header)});
        }

        getNext().invoke(request, response);
    }
}

Step 5: Open a terminal, and run mvn install. Now in the target/ folder, there jar should have been built.

Step 6: Copy this jar to ${TOMCAT_HOME}/lib or ${CATALINA_HOME}/lib folder. This is usually in /usr/local/apache-tomcat9/lib.

Step 7: Go to ${TOMCAT_HOME}/conf or ${CATALINA_HOME}/conf folder and add the following line to server.xml:

Classname: TomcatValve

PackageName: com.keetmalin.tomcat

<Valve className="com.keetmalin.tomcat.TomcatValve"/>

Step 9: Go to ${TOMCAT_HOME}/bin or ${CATALINA_HOME}/bin folder and run the following command in a terminal:

./catalina.sh run

Step 10: Next, your Tomcat server will start. Open a browser and go to http://localhost:8080/ and go back to the terminal. You will see that the logs are being printed. Now instead of printing logs, you can do anything you wish. Hope it helps!

What version of Tomcat are you running? The CATALINA_HOME\lib is the correct directory for Tomcat v6.x (and v7, I believe). If your valve is not getting picked up it could be that you are not editing the server.xml or context.xml files in your CATALINA_BASE directory. Are you using Eclipse IDE or something similar? If so, check your Tomcat server settings because it copies XML files from CATALINA_HOME (installation) to CATALINA_BASE (configured instance) directory. This problem tripped me up for a while.

I found that I had created a jar which contained the java file, instead of the class file using netbeans.

The solution that worked for me was to create a jar with the correct directory structure for the package (MyValve.jar\org\apache\catalina\connector\) and stick the class file in that directory. I put the jar in the same location (CATALINA_HOME\lib).

I added an entry to the server.xml file inside the <Host> section like this:

<Valve className="org.apache.catalina.connector.MyValve"
    classField="value">