kolobok

Java Annotation Processor for Spring. It contains a set of annotations that makes working with Spring easier. It is inspired by Lombok.

@FindWithOptionalParams

Usually Spring Data Repository interface includes find methods. Something like

@Repository
public interface PersonRepo extends PagingAndSortingRepository<Person, Long> {
    Iterable<Person> findByFirstNameAndLastNameAndCityId(String firstName, String lastName, Long cityId);
}

But if you want to find only by cityId and lastName (without specifying firstName) you need to add new method

    Iterable<Person> findByLastNameAndCityId(String lastName, Long cityId);

@FindWithOptionalParams annotation allows you to use original findByFirstNameAndLastNameAndCityId method with null values for params which should not be used in search criteria.

@Repository
public interface PersonRepo extends PagingAndSortingRepository<Person, Long> {
    @FindWithOptionalParams
    Iterable<Person> findByFirstNameAndLastNameAndCityId(String firstName, String lastName, Long cityId);
}

So now you can call

    Iterable<Person> persons = personRepo.findByFirstNameAndLastNameAndCityId(null, "Smith", 1L);

How it works?

It generates all possible find methods for search params.

  Iterable<Person> cityId(Long cityId);
  Iterable<Person> lastName(String lastName);
  Iterable<Person> lastNameAndCityId(String lastName, Long cityId);
  Iterable<Person> firstName(String firstName);
  Iterable<Person> firstNameAndCityId(String firstName, Long cityId);
  Iterable<Person> firstNameAndLastName(String firstName, String lastName);
  Iterable<Person> firstNameAndLastNameAndCityId(String firstName, String lastName, Long cityId);

Also it generates default implementation of findByFirstNameAndLastNameAndCityId method that checks which params are null and calls corresponded method.

    default Iterable<Person> findByFirstNameAndLastNameAndCityId(String firstName, String lastName, Long cityId) {
      if(firstName == null) {
        if(lastName == null) {
          if(cityId == null) {
            return findAll();
          } else {
            return cityId(cityId);
          }
        } else {
          if(cityId == null) {
            return lastName(lastName);
          } else {
            return lastNameAndCityId(lastName, cityId);
          }
        }
      } else {
        if(lastName == null) {
          if(cityId == null) {
            return firstName(firstName);
          } else {
            return firstNameAndCityId(firstName, cityId);
          }
        } else {
          if(cityId == null) {
            return firstNameAndLastName(firstName, lastName);
          } else {
            return firstNameAndLastNameAndCityId(firstName, lastName, cityId);
          }
        }
      }
    }

@CompileTime

If you need to know when a class has been compiled, you can use this annotation and mark long/java.lang.Long fields with this annotation. Variable is going to be initialized with value from System.currentTimeMillis().

import org.kolobok.annotation.CompileTime;

public class Main {
    @CompileTime
    static long ct;
    
    public static void main(String args[]) {
        System.out.println("Class has been compiled at " + new Date(ct));
    } 
}

Output is

Class has been compiled at Sun Jan 26 12:31:04 MSK 2020

@BuildNumber

You can increment a field in a class every time when somebody compiles your application. You need a HTTP service that returns incrementing build number by every time when it's being called. You can use Backendless for this.

@import org.kolobok.annotation.BuildNumber;

public class Main {
    @BuildNumber(url = "https://api.backendless.com/${APP_ID}/${API_KEY}/counters/build/increment/get", method = "PUT")
    static long bn;
    
    public static void main(String args[]) {
        System.out.println("Build number = " + bn);
    } 
}

Output is

Build number = 1

After recompilation

Build number = 2

How to use Kolobok?

Just include kolobok library in your project. Maven:

  <dependency>
    <groupId>com.github.ukman</groupId>
    <artifactId>kolobok</artifactId>
    <version>0.1.5</version>
    <scope>compile</scope>  
  </dependency>

Gradle:

compileOnly 'com.github.ukman:kolobok:0.1.5'