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

 2  3 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

 2  3 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）