企业erp完成查询订单功能

完成查询所有订单并在页面上显示

1.首先，准备一个订单数据库 

2.创建一个实体类Orders 该类要与数据库对应 

package com.itheima.pojo;

public class Orders {
    private int order_id;
    private String customer_id;
    private String product_code;
    private String product;
    private int quantity;
    String order_date;
    String delivery_date;

    public int getOrder_id() {
        return order_id;
    }

    public void setOrder_id(int order_id) {
        this.order_id = order_id;
    }

    public String getCustomer_id() {
        return customer_id;
    }

    public void setCustomer_id(String customer_id) {
        this.customer_id = customer_id;
    }

    public String getProduct_code() {
        return product_code;
    }

    public void setProduct_code(String product_code) {
        this.product_code = product_code;
    }

    public String getProduct() {
        return product;
    }

    public void setProduct(String product) {
        this.product = product;
    }

    public int getQuantity() {
        return quantity;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }

    public String getOrder_date() {
        return order_date;
    }

    public void setOrder_date(String order_date) {
        this.order_date = order_date;
    }

    public String getDelivery_date() {
        return delivery_date;
    }

    public void setDelivery_date(String delivery_date) {
        this.delivery_date = delivery_date;
    }

    public Orders(int order_id, String customer_id, String product_code, String product, int quantity, String order_date, String delivery_date) {
        this.order_id = order_id;
        this.customer_id = customer_id;
        this.product_code = product_code;
        this.product = product;
        this.quantity = quantity;
        this.order_date = order_date;
        this.delivery_date = delivery_date;
    }

    public Orders() {

    }

    @Override
    public String toString() {
        return "Orders{" +
                "order_id=" + order_id +
                ", customer_id='" + customer_id + '\'' +
                ", product_code='" + product_code + '\'' +
                ", product='" + product + '\'' +
                ", quantity=" + quantity +
                ", order_date='" + order_date + '\'' +
                ", delivery_date='" + delivery_date + '\'' +
                '}';
    }
}

3.创建一个ordersMapper.xml 文件用来完成sql语句映射，简单的sql也可以用注释来操作

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.itheima.mapper.ordersMapper">

    <select id="selectOrders" resultType="com.itheima.pojo.Orders">
        select * from orders
    </select>


</mapper>

4.创建一个接口类ordersMapper 用来声明一些数据库操作的函数

package com.itheima.mapper;

import com.itheima.pojo.Orders;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;

import java.util.List;



public interface ordersMapper {

    List<Orders> selectOrders();

}

5. 接着完成创建DataService 该类用来实现ordersMapper里声明的函数具体功能

package com.itheima.Service;

import com.itheima.Util.MyBatisUtils;
import com.itheima.mapper.userMapper;
import com.itheima.mapper.ordersMapper;
import com.itheima.mapper.partsMapper;
import com.itheima.mapper.processesMapper;
import com.itheima.pojo.Orders;
import com.itheima.pojo.Parts;
import com.itheima.pojo.Processes;
import com.itheima.pojo.employees;
import org.apache.ibatis.session.SqlSession;

import java.util.List;

public class DataService {

    SqlSession sqlSession = MyBatisUtils.getSqlSession();

    /*
    * 获得订单信息
    * */
    public List<Orders> getOrders(){
        //第一步   获取sqlsession对象
        //第二步  执行sql
        ordersMapper ordersMapper =sqlSession.getMapper(ordersMapper.class);
        List<Orders>orders = ordersMapper.selectOrders();
        System.out.println(orders);
        sqlSession.close();
        return orders;
    }

}

6.接着创建一个OrderServlet 用来给前端传送数据

package com.itheima.Servlet;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.itheima.Service.DataService;
import com.itheima.pojo.Orders;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

@WebServlet("/OrderServlet")
public class OrderServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        DataService dataService = new DataService();
        List<Orders> orders = dataService.getOrders();

        /*
        * 使用FastJson将list转化成JSON
        * */
        String jsonDate = JSON.toJSONString(orders, SerializerFeature.WriteMapNullValue);
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");

        PrintWriter out = response.getWriter();//获取PrintWriter对象
        out.print(jsonDate);//将jsonDate这个json数据写入到PrintWriter中 实际上数据发送到与客户端相关联的输出流。
        out.flush();//方法用于强制将缓冲区中的内容发送到客户端



    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doGet(request,response);
    }
}

到此，查询订单的后端代码就写完了。

剩下在前端界面写ajax接受数据并显示。