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）