详解Spring Data JPA系列之投影（Projection）的用法

Select C from Customer c

select c.firstName as firstName,c.lastName as lastName from Customer c

package com.example.demo.dto;

import org.springframework.beans.factory.annotation.Value;

/**
 * Created by Administrator on 2017/7/9 0009.
 */
public interface CustomerProjection {
  @Value("#{target.firstName + ' ' + target.lastName}")
  String getFullName();

  String getFirstName();

  String getLastName();
}

  @Query("SELECT c.firstName as firstName,c.lastName as lastName from Customer c")
  Collection<CustomerProjection> findAllProjectedBy();

  /**
   * find by projections
   */
  @RequestMapping("/findAllProjections")
  public void findAllProjections(){
    Collection<CustomerProjection> projections = repository.findAllProjectedBy();
    System.out.println(projections);
    System.out.println(projections.size());
    for (CustomerProjection projection:projections){
      System.out.println("FullName:"+projection.getFullName());
      System.out.println("FirstName:"+projection.getFirstName());
      System.out.println("LastName:"+projection.getLastName());
    }
  }