调用rest api时，无论是否使用lomboks @Data，方法均未定义

Question

I have Spring web application in Maven with rest api. Project compiles and Tomcat server starts without problems, but when I call some rest service from browser I get error that getter method is undefined, the method that shoud be generated by Lombok.

I delombok-ed the class with this getter to see if Lombok have generated getter correctly and it did, the getter is there, but when the method is invoked by rest api call, then I get exception.

Lombok-ed class:

@XmlRootElement
@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table
public class HeroEntity
{
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @Version
    private int version;

    @Column
    private String name;

    @ManyToMany(mappedBy = "heroes")
    private List<ComicBookEntity> comicBooks;
}

Method that throws an exception:

@Override
    public HeroEntity add(HeroEntity heroEntity) throws DuplicateResourceException
    {
        try {
            return _heroRepository.save(heroEntity);
        }catch(final DataIntegrityViolationException e) {
            throw new DuplicateResourceException(ResourceType.HERO,
                    "Hero with id: "+heroEntity.getId()+" already exists");
        }
    }

Exception is thrown in the add method on the heroEntity.getId() call. That getter should be generated by Lombok, which it is as I delombok-ed the class and everything is fine, but I still get an exception.

pom.xml:

             <plugin>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok-maven-plugin</artifactId>
                <version>1.18.0.0</version>
                <executions>
                    <execution>
                        <phase>generate-sources</phase>
                        <goals>
                            <goal>delombok</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>



<dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.20</version>
            <scope>provided</scope>
        </dependency>

Answer 1

AFAIK Lombok "works" (ie generates methods, etc.) only during the compilation phase. All its annotations have a retention policy "SOURCE". Once lombok finishes method generation, its impossible in runtime to "distinguish" between native methods and the methods generated by lombok.

On the other hand, other annotations (JPA, JAXB here) get processed during runtime, so they won't interfere or something.

So I assume that, if in runtime the JVM complains that the method doesn't exist, it indeed not there.

Now if in runtime the method is not there, it's probably indeed not there :) The real question is whether Lombok didn't work at all or it generated something that JPA/Hibernate doesn't recognize as a valid method.

How to check this?

I suggest just to physically open your war file (again, I implicitly assume you have a WAR file in tomcat), locate the HeroEntity.class inside WEB-INF/lib/one-of-your-jars.jar and run it through some sort of Disassembler, like JAD or javap - just to see whats get generated. If you see that there is some getter, maybe its return type doesn't match Hibernate expectations (Long vs long, and so forth)

Alternatively, if there is no any getter at all, then Lombok didn't work and you should check your build

I know this is more a speculation rather than areal and precise answer, but It looks like there is not enough information here, not because the question is bad or something, but because that the chances are that there are much more configurations under the hood of your project that can influence the answer.