Get free jdbi ResultSetMapper if your class has a constructor from a ResultSet

ConstructorResultSetMapperFactory.java

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Optional;
import lombok.extern.slf4j.Slf4j;
import org.skife.jdbi.v2.ResultSetMapperFactory;
import org.skife.jdbi.v2.StatementContext;
import org.skife.jdbi.v2.tweak.ResultSetMapper;

/**
 * Automatically create a ResultSetMapper if the type has a constructor that accepts a ResultSet
 */
@Slf4j
public class ConstructorResultSetMapperFactory implements ResultSetMapperFactory {

  private static Optional<Constructor<?>> getConstructor(Class type) {
    try {
      return Optional.of(type.getConstructor(ResultSet.class));
    } catch (NoSuchMethodException | SecurityException ex) {
      return Optional.empty();
    }
  }

  
  private static class ConstructorResultSetMapper implements ResultSetMapper {

    private final Constructor constructor;
    
    public ConstructorResultSetMapper(Constructor constructor) {
      this.constructor = constructor;
    }
    
    @Override
    public Object map(int i, ResultSet rs, StatementContext sc) throws SQLException {
      try {
        return constructor.newInstance(rs);
      } catch(InvocationTargetException ex) {
        Throwable cause = ex.getCause();
        // Don't mangle useful exceptions!
        if(cause != null && cause instanceof SQLException) {
          throw (SQLException) cause;
        } else {
          throw new RuntimeException(ex);
        }
      } catch (InstantiationException | IllegalAccessException | IllegalArgumentException ex) {
        throw new RuntimeException(ex);
      }
    }
    
  }
  
  @Override
  public boolean accepts(Class type, StatementContext sc) {
    return getConstructor(type).isPresent();
  }

  private static ResultSetMapper fromConstructor(Constructor constructor) {
    log.debug("Automatically creating ResultSetMapper<{}> from constructor.", constructor.getDeclaringClass().getSimpleName());
    return new ConstructorResultSetMapper(constructor);
  }

  @Override
  public ResultSetMapper mapperFor(Class type, StatementContext sc) {
    return getConstructor(type)
      .map(ConstructorResultSetMapperFactory::fromConstructor)
      .orElseThrow(RuntimeException::new);
  }
}