SpringBoot+ Bean Seracher + mysql使用带条件查询

要在SpringBoot中使用BeanSeracher和MySQL进行带条件查询，可以按照以下步骤：

1. 首先，在pom.xml中添加以下依赖：

<dependency>
    <groupId>com.github.wenhao</groupId>
    <artifactId>jpa-spec</artifactId>
    <version>1.1.0</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

2. 在实体类中定义需要查询的属性，并在Repository接口中继承JpaSpecificationExecutor接口：

@Entity
@Table(name = "user")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private Integer age;
    private String email;
    // getter/setter省略

}

@Repository
public interface UserRepository extends JpaRepository<User, Long>, JpaSpecificationExecutor<User> {

}

3. 在Controller中定义查询接口，并使用BeanSeracher构造查询条件：

@RestController
@RequestMapping("/users")
public class UserController {
    @Autowired
    private UserRepository userRepository;

    @GetMapping("/search")
    public List<User> search(@RequestParam(required = false) String name,
                             @RequestParam(required = false) Integer age,
                             @RequestParam(required = false) String email) {
        Specification<User> specification = (root, query, criteriaBuilder) -> {
            List<Predicate> predicates = new ArrayList<>();
            if (name != null) {
                predicates.add(criteriaBuilder.like(root.get("name"), "%" + name + "%"));
            }
            if (age != null) {
                predicates.add(criteriaBuilder.equal(root.get("age"), age));
            }
            if (email != null) {
                predicates.add(criteriaBuilder.equal(root.get("email"), email));
            }
            return criteriaBuilder.and(predicates.toArray(new Predicate[0]));
        };
        return userRepository.findAll(specification);
    }
}

4. 使用Postman等工具测试查询接口，可以按照name、age、email等属性进行查询。例如：

GET http://localhost:8080/users/search?name=Tom&age=20

以上就是使用SpringBoot+ Bean Seracher + mysql实现带条件查询的步骤