Make JAR available to JDK and JRE

user_3684479 0
Viewed 97

I am running a web application using Tomcat, JDK8 and Netbeans IDE (using ANT for build and IVY for dependency management).

I currently place JARs that need to be available to the JRE (servlet-api.jar, jsp-api.jar, el-api.jar, tomcat-dbcp.jar) in JAVA_HOME/jre/lib/ext.

I'm upgrading to a new JDK version (JDK17), which no longer has the JRE extensions folder. I'm wondering where I should place these JARs.

According to this post (and others I've seen), it is better practice to use a dependency manager and add these jars to your classpath anyway.

I currently use IVY to manage my dependencies and have customized my ANT build to add run-time dependencies to the WEB-INF/lib folder of the built WAR file.

However, I do not need the JARs I listed above to be available to my application at runtime, I need them to be available to the JRE. That is, I do not want the JARs (servlet-api.jar, etc.) to be in WEB-INF/lib of my built WAR file. How can I do this?

Sharpening my final questions:

  1. How can I make certain JARs/dependencies available to the JRE in Netbeans in my development environment?
  2. How can I make certain JARs/dependencies available to the JRE in the built WAR file used on my production environment?
  3. Am I correct in saying that these JARs need to be available to the JRE? All of the posts I've seen discuss compile-time vs run-time dependencies but it seems the case I'm describing is a different category of dependency. Is this correct?
ivy netbeans build ant java
1 Answers

I currently place JARs that need to be available to the JRE (servlet-api.jar, jsp-api.jar, el-api.jar, tomcat-dbcp.jar) in JAVA_HOME/jre/lib/ext.

That's not the best way to do things. See Is putting external jars in the JAVA_HOME/lib/ext directory a bad thing?

Note that the jre/lib/ext mechanism has been removed from newer versions of Java, so this will not work anymore if you use a newer version of Java. (This has been removed in JDK 9).

However, I do not need the JARs I listed above to be available to my application at runtime, I need them to be available to the JRE.

Why?

That is, I do not want the JARs (servlet-api.jar, etc.) to be in WEB-INF/lib of my built WAR file. How can I do this?

Why not? Putting the dependencies that your application needs in WEB-INF/lib is the normal thing to do in Java web applications. Why do you want to do things the non-standard way?

But: Some JAR files, such as servlet-api.jar, jsp-api.jar and el-api.jar are not supposed to be included in your application. Those JAR files define standard Java EE / Jakarta EE APIs and will be provided to your application at runtime by the application server (Tomcat, etc.) that you deploy your WAR file in.

You can add those JAR files as dependencies using Maven with provided scope, which means they will be used while compiling, but won't be packaged into your application.

Am I correct in saying that these JARs need to be available to the JRE?

No, those JARs do not need to be available to the JRE. JAR files that contain standard APIs will be provided by your Java EE / Jakarta EE container at runtime. Other JAR files should be included in your application in WEB-INF/lib.

user_1355890
Related