javascript html json 前端 java servlet mybatis 前后端功能实现——查询所有

目录

1、需求

2、步骤

1）创建模块 引入坐标

2）创建结构 实现三层架构

3）创建表 brand 

4）创建实体类 Brand

5）创建MyBatis配置文件

6）创建映射文件

7）创建工具类 SqlSessionFactoryUtils

8）创建BrandService类

9）创建SelectAllServlet类

10）后端启动测试

________________

11）创建brand.html

12）加入JS：绑定事件、发送异步请求、处理响应数据

1、需求

前后端以JSON格式进行数据传递：此功能前端发送Ajax请求不需要携带参数，而后端响应数据需要JSON格式数据。

2、步骤

分析：

1）创建模块 引入坐标

创建模块或project

分析需要哪些依赖：

操作数据库用MySQL的驱动、MyBatis框架；Web应用用到Servlet、fastjson。

pom.xml：

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

4.0.0

com.example

brandCRUD

1.0-SNAPSHOT

brandCRUD

war

UTF-8

1.8

1.8

5.8.1

javax.servlet

javax.servlet-api

4.0.1

provided

mysql

mysql-connector-java

8.0.33

org.mybatis

mybatis

3.5.5

com.alibaba

fastjson

1.2.83

org.junit.jupiter

junit-jupiter-api

${junit.version}

test

org.junit.jupiter

junit-jupiter-engine

${junit.version}

test

org.apache.maven.plugins

maven-war-plugin

3.3.2

2）创建结构 实现三层架构

3）创建表 brand 

-- 创建brand表

create table brand

(

-- id 主键

id int primary key auto_increment,

-- 品牌名称

brand_name varchar(20),

-- 简介

brand_intro varchar(200),

-- 排序字段

ordered int,

-- 状态：0：禁用 1：启用

status int

);

-- 添加数据

insert into brand (brand_name, brand_intro, ordered, status)

values ('洲际酒店', '知行天下', 100, 0),

('希尔顿', '带着目的去旅行，带着故事回家', 10, 1),

('哈斯利酒店', '罗马的静谧绿洲，悠久的历史与现代的奢华完美融合', 1000, 1);

SELECT * FROM brand;

4）创建实体类 Brand

在 pojo 中创建Brand类：

package com.example.brandcrud.pojo;

public class Brand {

// id 主键

private Integer id;

private String brandName; // 品牌名称

private String brandIntro; // 简介

private Integer ordered; // 排序

private Integer status; // 状态:0:禁用 1:启用

public Brand() {

}

public Brand(Integer id, String brandName, String brandIntro, Integer ordered, Integer status) {

this.id = id;

this.brandName = brandName;

this.brandIntro = brandIntro;

this.ordered = ordered;

this.status = status;

}

public Integer getId() {

return id;

}

public void setId(Integer id) {

this.id = id;

}

public String getBrandName() {

return brandName;

}

public void setBrandName(String brandName) {

this.brandName = brandName;

}

public String getBrandIntro() {

return brandIntro;

}

public void setBrandIntro(String brandIntro) {

this.brandIntro = brandIntro;

}

public Integer getOrdered() {

return ordered;

}

public void setOrdered(Integer ordered) {

this.ordered = ordered;

}

public Integer getStatus() {

return status;

}

public void setStatus(Integer status) {

this.status = status;

}

@Override

public String toString() {

return "Brand{" +

"id=" + id +

", brandName='" + brandName + '\'' +

", brandIntro='" + brandIntro + '\'' +

", ordered=" + ordered +

", status=" + status +

'}';

}

}

5）创建MyBatis配置文件

resources中创建Mybatis-config.xml文件：

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd">

6）创建映射文件

resources中创建映射配置文件目录：com/example/brandcrud/mapper，

在这个文件夹中创建映射文件 BrandMapper.xml：

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

7）创建工具类 SqlSessionFactoryUtils

utils中创建SqlSessionFactoryUtils类：

public class SqlSessionFactoryUtils {

private static SqlSessionFactory sqlSessionFactory;

static { //静态代码块会随着类的加载而自动执行，且只执行一次 try {

String resource = "mybatis-config.xml";

InputStream inputStream = null;

try {

inputStream = Resources.getResourceAsStream(resource);

sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

} catch (IOException ex) {

ex.printStackTrace();

}

}

public static SqlSessionFactory getSqlSessionFactory(){

return sqlSessionFactory;

}

}

8）创建BrandMapper接口

在mapper文件夹中创建接口，在接口中定义 selectAll() 方法：

public interface BrandMapper {

/**

* 查询所有

*/

@Select("select * from brand")

List selectAll();

}

9）创建BrandService类

service中创建BrandService类，进行逻辑处理：

public class BrandService {

//获取SqlSessionFactory

SqlSessionFactory factory= SqlSessionFactoryUtils.getSqlSessionFactory();

/**

* 查询所有

*/

public List selectAll(){

//调用mapper层的selectAll方法

//获取sqlSession对象

SqlSession sqlSession=factory.openSession();

//获取BrandMapper

BrandMapper mapper=sqlSession.getMapper(BrandMapper.class);

//调用方法

List brands=mapper.selectAll();

sqlSession.close();

return brands;

}

}

10）创建SelectAllServlet类

web中创建一个Servlet类：

@WebServlet("/selectAll")

public class SelectAllServlet extends HttpServlet {

private BrandService brandService=new BrandService();

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

//调用service层的selectAll()方法 进行查询所有的逻辑处理

List brands=brandService.selectAll();

//将集合转换为JSON数据：序列化

//如果是将JSON数据转换为Java对象，称为反序列化

String jsonString= JSON.toJSONString(brands);

//将JSON数据响应给浏览器 要设置响应数据的类型及字符集

response.setContentType("text/json;charset=utf-8");

response.getWriter().write(jsonString);

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

this.doPost(request, response);

}

}

后端启动测试

数据表中的品牌名、简介没有显示：

因为查询到的字段名和实体类对象的属性名没有一一对应，要在映射配置文件中使用resultMap定义映射关系。BrandMapper.xml修改为：

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

并且要在 BrandMapper 接口中的 selectAll() 上使用 @ResuleMap 注解指定使用该映射：

BrandMapper接口修改为：

public interface BrandMapper {

/**

* 查询所有

*/

@Select("select * from brand")

@ResultMap("brandResultMap")

List selectAll();

}

或者使用起别名的方式：

在BrandMapper.xml中的sql语句：

select id, brand_name as brandName, brand_intro as brandIntro, ordered,status from brand;

_________________

11）创建brand.html

webapp中创建（此处放到了project的webapp目录中，没有使用模块的webapp文件夹）

12）加入JS：绑定事件、发送异步请求、处理响应数据

webapp中新建js文件夹，存入axios的js文件，文件名为axios-0.18.0.js：

/* axios v0.18.0 | (c) 2018 by Matt Zabriskie */

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*

* @author Feross Aboukhadijeh

* @license MIT

*/

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//# sourceMappingURL=axios.min.map

继续编写brand.html，加入JavaScript部分：

将数据与表格拼接的思路：

拼接字符串：将表格中的所有的 tr 拼接到一个字符串中，然后使用 document.getElementById("brandTable").innerHTML = 拼接好的字符串，就可以动态的展示数据。而表头行是固定的，先定义初始值是表头行数据的字符串。

启动访问：

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