spring data jpa 关联join查询出自定义实体java bean的坑

repository接口如下：

package cn.detao.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;

import cn.detao.domain.Role;
import cn.detao.domain.User;
import java.lang.String;
import java.util.List;

public interface UserRepository  extends JpaRepository<User, Integer>  {
	
	User findByName(String name);

	User findByUsername(String username);
	
	@Query(value = "SELECT new cn.detao.domain.Role(r.id,r.name,r.nameZh) FROM User u INNER JOIN UserRole ur ON u.id = ur.userId INNER JOIN Role r ON ur.roleId = r.id WHERE u.id = ?1")
	List<Role> findRolesByUser(Integer UserId);

}

role实体：

package cn.detao.domain;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

import lombok.Data;

@Entity
@Data
public class Role {

	@Id // 主键
	@GeneratedValue(strategy = GenerationType.IDENTITY) // 自增长策略
	private Integer id;

	@Column
	private String name;
	@Column
	private String nameZh;

	public Role(Integer id, String name, String nameZh) {
		super();
		this.id = id;
		this.name = name;
		this.nameZh = nameZh;
	}
	
	public Role() {
		
	}

}

注意大坑：

SELECT new cn.detao.domain.Role(r.id,r.name,r.nameZh) FROM User u INNER JOIN UserRole ur ON u.id = ur.userId INNER JOIN Role r ON ur.roleId = r.id WHERE u.id = ?1

查询语句中的所有表名必须是 javaBean 实体名，不能是mysql表名；字段名也必须是javaBean实体里的属性名，不能是mysql表里的字段名。