Spring Date JPA实现增删改查

1.新建一个Cart类

package com.entity;

public class Cart {
    private int id;
    private int userId;
    private int medicineId;
    private int count;
    private int price;
    private String medicineName;
    private String medicineSize;
    private int status;
}

2.添加注解

@Entity //表示是一个实体类
@Table(name = "tbl_cart") //指定数据库中对应的表
public class Cart {

    @Id //指定主键
    @GeneratedValue(strategy = GenerationType.IDENTITY) //自增
    private int id;
    private int userId;
    private int medicineId;
    private int count;
    private int price;
    private String medicineName;
    private String medicineSize;
    private int status;
}

后面添加get、set方法和toString方法

3.创建实体类的CartRepository接口

package com.Dao;

import com.entity.Cart;
import org.springframework.data.jpa.repository.JpaRepository;

public interface CartRepository extends JpaRepository<Cart,Integer> {
}

接口继承JpaRepository<操作的实体类，主键类型>

接口默认实现了增删改查等一些简单的操作，其他操作可以参考Spring Data JPA根据属性名查询在接口类中直接创建。

4.创建CartService类

创建CartService类然后添加service层注解，然后在类中实现各种方法。

package com.service;

import com.Dao.CartRepository;
import com.entity.Cart;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;

@Service
public class CartService {

    @Resource
    CartRepository cartRepository;

    //查询全部
    public List<Cart> findAll(){
        return this.cartRepository.findAll();
    }
}

5.创建CartController

RestController只能返回String类型的数据

package com.controller;

import com.entity.Cart;
import com.google.gson.Gson;
import com.service.CartService;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.List;

@RestController
@RequestMapping("/cart")
public class CartController {

    @Resource
    CartService cartService;
    Gson gson = new Gson();

    //获取所有购物车信息
    @RequestMapping(value = "/list")
    public String list()
    {
        List<Cart> cartList = this.cartService.findAll();
        String result = gson.toJson(cartList);
        return result;
    }
}

6.通过post或者get请求访问服务器

http://localhost:8070/onepill/cart/list

参考：JPA概述