20220720

本例在已经有项目代码基础上扩展，
参考本贴的准备工作部分
完成后结构图
brand-demo模块

因为要用到JSON语句，所以要导入JSON的坐标，maven的pom.xml最后如下

    4.0.0

    org.example
    brand-demo
    1.0-SNAPSHOT

    war

    
        8
        8
    


    
        
            org.mybatis
            mybatis
            3.5.10
        
        
            mysql
            mysql-connector-java
            8.0.29
        
        
            javax.servlet
            javax.servlet-api
            4.0.1
            provided
        
        
            javax.servlet.jsp
            jsp-api
            2.2
            provided
        

        
        
            jstl
            jstl
            1.2
        
        
            taglibs
            standard
            1.1.2
        
        
        
            com.alibaba
            fastjson
            2.0.7
        

    

    
        
            
                org.apache.tomcat.maven
                tomcat7-maven-plugin
                2.2
            
        
    
    

mybatis-config.xml也给一个，数据库的数据自行准备

写对应的查询servlet

package com.diy.web;

import com.alibaba.fastjson.JSON;
import com.diy.pojo.Brand;
import com.diy.service.BrandService;

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

@WebServlet("/queryAllServlet")
public class queryAllServlet extends HttpServlet {
    //get a service object
    private BrandService bsr = new BrandService();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //query all brand info
        List brands = bsr.selectAll();
        //convert it to json, serialization
        String jsonBrands = JSON.toJSONString(brands);
        //response to html
        resp.setContentType("text/json;charset=utf-8");
        resp.getWriter().write(jsonBrands);

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}

写好servlet如果访问http://localhost:8080/brand-demo/servlet可以看到

list数据经json传给网页后，输出是一个数组的格式
访问http

    
    


添加品牌

    品牌名称：

    企业名称：

    排序：

    描述信息：

    状态：
    禁用
    启用


    
    
    

对应的servlet

package com.diy.web;

import com.alibaba.fastjson2.JSON;
import com.diy.pojo.Brand;
import com.diy.service.BrandService;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.BufferedReader;
import java.io.IOException;

@WebServlet("/addServlet")
public class addServlet extends HttpServlet {
    //get a service object
    private BrandService bsr = new BrandService();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
//        String brandName = req.getParameter("brandName");
//        System.out.println(brandName);

        //1.through right way receive data in post
        req.setCharacterEncoding("utf-8");

        BufferedReader reader = req.getReader();
        String data = reader.readLine();//no matter how long the data is ,it is one line

        //2.convert to brand ob
        Brand brand = JSON.parseObject(data, Brand.class);
        System.out.println(brand);

        //3.insert into database
        bsr.add(brand);
        //4.if no exception
        resp.getWriter().write("1");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}

访问添加功能的网址

提交后idea的控制台根据代码输出

有乱码，是我的系统环境原因，无法解决，但提交后的网页正常，因为代码里对应乱码有代码
数据库里也是正常的
直接在数据库改了一下内容

完