自定义注释的 Intellij 代码检查

Question

One of the problems I've encountered while using DTOs is that I often find myself shipping (accidentally) entities along with DTOs. To mitigate this problem, I created another Maven project with an annotation (@ValidDTO) and its processor that finds if a DTO annotated with @ValidDTO has @Entity annotated fields.

This is my annotation.

@Retention(RetentionPolicy.CLASS)
@Target(ElementType.TYPE)
public @interface ValidDTO {}

And, this is my processor.

@SupportedAnnotationTypes("com.aj.annotations.ValidDTO")
@SupportedSourceVersion(SourceVersion.RELEASE_11)
public class ValidDTOProcessor extends AbstractProcessor {

    @Override
    public boolean process(Set<? extends TypeElement> set,
                           RoundEnvironment roundEnv) {

        List<Entity> entityFields = roundEnv.getElementsAnnotatedWith(ValidDTO.class)
                .stream()
                .filter(element -> element.getKind()==ElementKind.CLASS || element.getKind()==ElementKind.INTERFACE)
                .map(Element::getEnclosedElements)
                .flatMap(List::stream)
                .filter(element -> element.getKind()==ElementKind.FIELD)
                .map(element -> element.getAnnotation(Entity.class))
                .collect(Collectors.toList());

            if (!entityFields.isEmpty()) {
            processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, "Types annotated with ValidDTO " +
                    "cannot have member variables that are @Entity annotated");
        }

        return true;
    }
}

This is how my POM.xml looks for the Maven project with the annotation and its processor

 <groupId>com.aj</groupId>
    <artifactId>aj-annotations</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                    <generatedSourcesDirectory>${project.build.directory}/generated-sources/
                    </generatedSourcesDirectory>
                    <proc>none</proc>
                    <annotationProcessors>
                        <annotationProcessor>
                            com.aj.annotations.processors.ValidDTOProcessor
                        </annotationProcessor>
                    </annotationProcessors>
                    <debug>true</debug>
                </configuration>
            </plugin>
        </plugins>
    </build>

So, I installed this package as a dependency in another projected and annotated a DTO with it. I purposefully added couple of entities as member variables to see the error.

@ValidDTO
public class FacilityDTO {
  private User user;
  private List<User> users;
}

where,

@Entity
@Table("User")
public class User {} 

is an entity.

Now, my custom annotation works perfectly good when I run mvn clean install or build project. I can see the expected "Types annotated with ValidDTO cannot have member variables that are @Entity annotated" in the terminal.

However, I do not see the error in the editor of the IDE. I've tried both Intellij and Eclipse and I do not see any red squiggly line underneath the annotation telling me that the DTO is invalid.

The closest expected desired behavior I can reference is a compile error when using @FunctionalInterface on an interface that has more than one abstract method.

I just need help configuring my IDE. Any help is appreciated!

Answer 1

In IntelliJ you can create custom inspections. These can be used to alert you to the presence of custom search patterns in your code ( https://www.jetbrains.com/help/idea/creating-custom-inspections.html ).

For your case: Go to settings -> Editor -> Inspections. Activate "Structural search inspection" and add a "Search Template":

(UPDATE 06/2020: "Structural search" is not under "General" anymore but is now a separate topic)

Add following structural search:

You may change "Severity" to "Error" to get the red squiggly lines. :)