springboot对jpa的支持

导入相关pom依赖

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

application.yml文件配置

spring:
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true

自动建表相关代码

package com.zking.springboot04.entity;

import javax.persistence.*;

/**
 * @author Zhang
 * @site www.zhangmage.com
 * @company zking
 * @create 2019-02-21 16:01
 */
@Entity
@Table(name = "t_springboot_order")
public class Order {
    @Id
    @GeneratedValue
    private Integer oid;
    @Column(length = 100)
    private String orderName;
    @Column
    private Float total;

    public Integer getOid() {
        return oid;
    }

    public void setOid(Integer oid) {
        this.oid = oid;
    }

    public String getOrderName() {
        return orderName;
    }

    public void setOrderName(String orderName) {
        this.orderName = orderName;
    }

    public Float getTotal() {
        return total;
    }

    public void setTotal(Float total) {
        this.total = total;
    }

}

数据库自动建表截图

会创建一个序列以及t_springboot_order表

jpa的增删改查

dao层

* 只要继承JpaRepository，通常所用的增删查改方法都有
 *  第一个参数：操作的实体类
 *  第二个参数：实体类对应数据表的主键
 */
public interface JpaDao extends JpaRepository<Order, Integer> {
}

service层

service：
package com.zking.springboot04.service;

import com.zking.springboot04.entity.Order;

import java.util.List;

/**
 * @author Zhang
 * @site www.zhangmage.com
 * @company zking
 * @create 2019-02-21 16:10
 */
public interface OrderService {
    public Order save(Order order);
    public void deleteById(Integer id);
    public List<Order> list(Order order);
}



serviceimpl

package com.zking.springboot04.service.impl;

import com.zking.springboot04.dao.OrderDao;
import com.zking.springboot04.entity.Order;
import com.zking.springboot04.service.OrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Service;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import java.util.List;

/**
 * @author Zhang
 * @site www.zhangmage.com
 * @company zking
 * @create 2019-02-21 16:12
 */
@Service
public class OrderServiceImpl implements OrderService {
    @Autowired
    private OrderDao orderDao;
    @Override
    public Order save(Order order) {
        return orderDao.save(order);
    }

    @Override
    public void deleteById(Integer id) {
    orderDao.deleteById(id);
    }

controller层

package com.zking.springboot04.controller;

import com.zking.springboot04.entity.Order;
import com.zking.springboot04.service.OrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * @author Zhang
 * @site www.zhangmage.com
 * @company zking
 * @create 2019-02-21 16:24
 */
@RestController
public class OrderController {
    @Autowired
    private OrderService orderService;
    @RequestMapping("/order/list")
    public List<Order> list(Order order){
        return orderService.list(order);
    }

    @RequestMapping("/order/add")
    public Order add(Order order){
        return orderService.save(order);
    }

    @RequestMapping("/order/edit")
    public Order edit(Order order){
        return orderService.save(order);
    }

    @RequestMapping("/order/del")
    public String del(Order order){
        orderService.deleteById(order.getOid());
        return "success";
    }

在浏览器中输入请求进行测试

jpa复杂查询

dao层

 *  要使用高级查询必须继承
 * org.springframework.data.jpa.repository.JpaSpecificationExecutor<T>接口
 */
public interface JpaDao extends JpaRepository<Order, Integer>, JpaSpecificationExecutor<Order> {
}

service层

service
public List<Order> list(Order order)


serviceimpl
 @Override
    public List<Order> list(Order order) {
        //这个方法就是用来重写他的一个查询，带什么条件都在里面写
        return orderDao.findAll(new Specification<Order>() {
            @Override
            public Predicate toPredicate(Root<Order> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                Predicate predicate=criteriaBuilder.conjunction();
                if(order!=null&&order.getOrderName()!=null&&!"".equals(order.getOrderName())){

                    predicate.getExpressions().add(criteriaBuilder.like(root.get("orderName"),"%"+order.getOrderName()+"%"));

                }
                return predicate;
            }
        });
    }

jpa查单个

service层

service 
public Order getOne(Integer id);


serviceimpl
 @Override
    public Order getOne(Integer id) {
        return orderDao.findById(id).get();
    }

controller层 

 @RequestMapping("/order/getOne")
    public Order getOne(Order order){
        return orderService.getOne(order.getOid());
    }

要注意的点：

springboot的jpa可以自动生成表（hibernate本质也是可以的）
jpa如果只是普通的增删查改只要继承jpaRepository就可以了
jpa要用到复杂的查询需要用到jpaSpecificationExecutor

在springboot2之前springboot它的getOne是可以用的

在springboot2之后springboot它的getOne变成懒加载了