QueryByExampleExecutor

可以通过实体进行简单的查询。比如我们查询用于昵称是超级开头的用户。

@RestController
@RequestMapping("/user")
public class UserController {

    @Resource
    private SysUserRepository sysUserRepository;

    @GetMapping("/findAll")
    @Transactional
    public List<SysUser> findAll() {
        SysUser sysUser = new SysUser();
        sysUser.setNickName("超级");
        ExampleMatcher exampleMatcher = ExampleMatcher.matching()
                .withMatcher("nickName", ExampleMatcher.GenericPropertyMatchers.startsWith())
                .withIgnorePaths("focus");
        Example<SysUser> sysUserExample = Example.of(sysUser, exampleMatcher);
        return sysUserRepository.findAll(sysUserExample);
    }

}

其实跟MyBatis-Plus类似，功能比较简单，只能拼接and查询，一般使用不是很多。

JpaSpecificationExecutor

使用Specification的要点就是CriteriaBuilder，通过这个对象来创建条件，之后返回一个Predicate对象。这个对象中就有了相应的查询需求，我们同样可以定义多个Specification，之后通过Specifications对象将其连接起来。

修改接口

public interface SysUserRepository extends JpaRepository<SysUser, Long>, JpaSpecificationExecutor<SysUser> {


}

测试

@RestController
@RequestMapping("/user")
public class UserController {

    @Resource
    private SysUserRepository sysUserRepository;

    @GetMapping("/findAll")
    @Transactional
    public List<SysUser> findAll() {
        return sysUserRepository.findAll((root, criteriaQuery, criteriaBuilder) -> {
            Predicate p1 = criteriaBuilder.like(root.get("nickName"), "%超级%");
            Predicate p2 = criteriaBuilder.equal(root.get("userName"), "admin");
            Predicate p3 = criteriaBuilder.equal(root.get("email"),"ry@163.com");
            return criteriaBuilder.and(p1, p2);
        });
    }

}