Java 9: how to get access to javax.annotation.Resource at run time

Question

I have a test:

public class ResourceTest {

    @Test

    public void test() throws ClassNotFoundException {

        Class.forName("javax.annotation.Resource");

    }

}

It tries to access

javax.annotation.Resource

. In java 8 it worked, but in java 9 (I'm using Oracle JDK 9) it fails with

ClassNotFoundException

.
As explained here Spring: @Resource injection stopped working under JDK9 ,

javax.annotation.Resource

from the JDK is not available by default in Java 9.

I'm trying to get access to it using module descriptor:

module test {

    requires java.xml.ws.annotation;

    requires junit;

}

Here, I specifically request access to

java.xml.ws.annotation

module (which contains

javax.annotation.Resource

). But the test still fails.

When I remove that

requires

clause and add a dependency (as a library) which contains

javax.annotations.Resource

, it works:

    <dependency>

        <groupId>javax.annotation</groupId>

        <artifactId>javax.annotation-api</artifactId>

        <version>1.3.1</version>

    </dependency>

When I add them both (Maven dependency in

pom.xml

and

requires java.xml.ws.annotation

), compilation in IDEA fails with the following message:

the unnamed module reads package javax.annotation from both java.xml.ws.annotation and java.annotation

But Maven build still succeeds!

If I add

java.xml.ws.annotation

module via command line, it works (with no Maven dependency and with

requires

clause):

mvn clean test -DargLine="--add-modules java.xml.ws.annotation"

Do I do something wrong with my module description? How can I get access to JDK-supplied

javax.annotation.Resource

without command line switches?

The test project is available at https://github.com/rpuch/test-resource-jdk9

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Answer 1

Just to clear out some confusion here. The ways to work stated in the question by you are alternatives and should not be combined as you have already seen.

the unnamed module reads package javax.annotation from both java.xml.ws.annotation and java.annotation

So the way it would work is either:

You can use the compiler args to add modules

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.7.0</version>
    <configuration>
        <release>9</release>
        <compilerArgs>
            <arg>--add-modules</arg>
            <arg>java.xml.ws.annotation</arg>
        </compilerArgs>
    </configuration>
</plugin>

OR

Make use of the javax.xml.ws.annotation being an upgradeable module which is when you can make use of the dependency

<dependency>
    <groupId>javax.annotation</groupId>
    <artifactId>javax.annotation-api</artifactId>
    <version>1.3.1</version>
</dependency>

Ideally this would be a preferrable option to stick to as the former is just an alternate to use the @Deprecated module marked forRemoval.

So the required clause by itself it not enough to get access to a module... is this true for all JDK-supplied modules (excluding java.base), or it is only true for deprecated modules?

No, the requires is just a part of declaration. [Think about this, prior to JDK 9 if you used a statement import some.foo.bar; in your class which was not added as a library(classpath) would that have worked?]. The module marked as required has to be on the modulepath for you to access it.

Java 9: how to get access to javax.annotation.Resource at run time

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