springboot jpa 多条件查询（单表）

需要实现的功能：

多个搜索输入框；全部不填，则查出所有列表；填了条件，就按条件查找；填的条件个数不定。

方法实现的核心：jpa自带的Specification<T>

（目前只需要单表，多表其实差不多）

话不多说，直接上代码。

实体类

 import lombok.Data;

 import javax.persistence.Entity;

 import javax.persistence.Id;

 /**

  * Created by 孙义朗 on 2017/11/14 0014.

  */

 @Entity

 @Data

 public class Employee {

     @Id

     private String id;

     private String name;

     private String age;

 }

接口

   import org.springframework.data.jpa.domain.Specification;

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

 import java.util.List;

 /**

  * Created by 孙义朗 on 2017/11/14 0014.

  */

 public interface EmployeeRepository extends JpaRepository<Employee, String>{

     List<Employee> findAll(Specification<Employee> spc, Pageable pageable);

 }

控制器

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

 import org.springframework.data.domain.PageRequest;

 import org.springframework.data.domain.Pageable;

 import org.springframework.data.jpa.domain.Specification;

 import org.springframework.web.bind.annotation.*;

 import javax.persistence.criteria.*;

 import java.util.ArrayList;

 import java.util.List;

 /**

  * Created by 孙义朗 on 2017/11/14 0014.

  */

 @RestController

 public class EmployeeController {

     @Autowired

     EmployeeRepository employeeRepository;

     //查询所有Employee

     @PostMapping(value = "/getEmployee/{pageNum}/{pageSize}")

     public List<Employee> getEmployee(@PathVariable("pageNum") Integer pageNum,

                                       @PathVariable("pageSize") Integer pageSize,

                                       @RequestBody Employee employee) {

         Pageable pageable = new PageRequest(pageNum, pageSize);

         List<Employee> eList = employeeRepository.findAll(new Specification<Employee>() {

             @Override

             public Predicate toPredicate(Root<Employee> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder cb) {

                 Path<String> id = root.get("id");

                 Path<String> name = root.get("name");

                 Path<String> age = root.get("age");

                 List<Predicate> predicates = new ArrayList<>();

                 if (employee.getId() != null && !employee.getId().equals("")) {

                     predicates.add(cb.like(id.as(String.class), "%" + employee.getId() + "%"));

                 }

                 if (employee.getName() != null && !employee.getName().equals("")) {

                     predicates.add(cb.like(name.as(String.class), "%" + employee.getName() + "%"));

                 }

                 if (employee.getAge() != null && !employee.getAge().equals("")) {

                     predicates.add(cb.like(age.as(String.class), "%" + employee.getAge() + "%"));

                 }

                 Predicate[] pre = new Predicate[predicates.size()];

                 criteriaQuery.where(predicates.toArray(pre));

                 return cb.and(predicates.toArray(pre));

             }

         }, pageable);

         return eList;

     }

 }

postman测试效果

（多表查询http://www.cnblogs.com/arrrrrya/p/7865090.html）