20220715_JaveWeb_MVC模式_三层架构案例

原创 已于 2022-07-16 01:10:54 修改 · 702 阅读 · 0 ·
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文章标签：

#mvc #架构 #mybatis

于 2022-07-16 00:51:10 首次发布
本文详细介绍了使用JavaWeb、MVC模式、MyBatis实现品牌数据库的增删改查操作。通过实例展示了如何配置Maven、MyBatis核心配置文件、Brand类、Mapper接口和映射文件，以及Service类、Servlet和JSP页面的交互，解决乱码问题，完成数据的完整生命周期操作。

JavaWeb实现品牌数据库的增删改查案例
涉及mybatis，servlet， jsp等

文章目录


准备工作部分

先准备一个数据库

show databases ;
use mybatis;
show tables ;

drop table if exists brand;
create table brand
(
    id      int primary key auto_increment,
    brand_name    varchar(20),
    company_name varchar(20),
    ordered int, -- 用于将来手动排序
    description varchar(100),
    status int -- 0 禁用 1 启用
);


insert into brand(brand_name, company_name, ordered, description, status)
values ('马大帅', '马大帅打工子弟小学', 5, '一个情儿字活一生', 0),
       ('依然范德彪', '维多利亚玉乐广场', 10, '我曾经年少轻狂', 1),
       ('罗翔说刑法', '厚大法考', 20, '女生宿舍居然有哑铃', 1);

select *
from brand;

图
请添加图片描述
本例完整结构图
请添加图片描述
maven的pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>MVC_Demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>war</packaging>

    <properties>
        <maven.compiler.source>18</maven.compiler.source>
        <maven.compiler.target>18</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.10</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.29</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
            <scope>provided</scope>
        </dependency>

        <!--jstl tags-->
        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>taglibs</groupId>
            <artifactId>standard</artifactId>
            <version>1.1.2</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
            </plugin>
        </plugins>
    </build>
</project>

mybatis的核心配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <typeAliases>
        <!--配置别名之后，全限名的包名就可以省略了-->
        <package name="com.diy.pojo"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <!--数据库链接信息-->
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///mybatis?useSSl=false&amp;useServerPrepStmts=true"/>
                <property name="username" value="root"/>
                <property name="password" value="1234"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--此处加载sql的映射文件-->
        <package name="com.diy.mapper"/>
    </mappers>
</configuration>

用于封装的品牌类

package com.diy.pojo;

/**
 * 品牌实体类
 */

public class Brand {
    // id 主键
    private Integer id;
    // 品牌名称
    private String brandName;
    // 企业名称
    private String companyName;
    // 排序字段
    private Integer ordered;
    // 描述信息
    private String description;
    // 状态：0：禁用  1：启用
    private Integer status;


    public Brand() {
    }

    public Brand(Integer id, String brandName, String companyName, String description) {
        this.id = id;
        this.brandName = brandName;
        this.companyName = companyName;
        this.description = description;
    }

    public Brand(Integer id, String brandName, String companyName, Integer ordered, String description, Integer status) {
        this.id = id;
        this.brandName = brandName;
        this.companyName = companyName;
        this.ordered = ordered;
        this.description = description;
        this.status = status;
    }

    public Integer getId() {
//        System.out.println("getId method has be invoked~~~");
        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 getCompanyName() {
        return companyName;
    }

    public void setCompanyName(String companyName) {
        this.companyName = companyName;
    }

    public Integer getOrdered() {
        return ordered;
    }

    public void setOrdered(Integer ordered) {
        this.ordered = ordered;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public Integer getStatus() {
        return status;
    }

    public void setStatus(Integer status) {
        this.status = status;
    }

    @Override
    public String toString() {
        return "Brand{" +
                "id=" + id +
                ", brandName='" + brandName + '\'' +
                ", companyName='" + companyName + '\'' +
                ", ordered=" + ordered +
                ", description='" + description + '\'' +
                ", status=" + status +
                '}';
    }
}

用于生成sql会话工厂的类，静态代码块一次生成，复数调用

package com.diy.util;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class SqlSessFactUtils {
    private static SqlSessionFactory ssf;

    static {

        try {
            String resource = "mybatis-config.xml";
            InputStream ins = Resources.getResourceAsStream(resource);
            ssf = new SqlSessionFactoryBuilder().build(ins);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSessionFactory getSsf(){
        return ssf;
    }

}

文章目录


开始编写需求对应的代码
第一步，显示所有品牌数据
写一个项目地址默认就会访问的html页面，index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Start Page</title>
</head>
<body>
    <a href="/MVC_Demo/selectAllServlet"> Query all Brands Info</a>
</body>
</html>

此首页点击超链接会提交给第一个servlet

package com.diy.web;

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("/selectAllServlet")
public class SelectAllServlet extends HttpServlet {
    /**
     * multi usage service object, so we put it here as a static resource
     */
    private BrandService bse = new BrandService();
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // invoke method in service to query
        List<Brand> brs = bse.selectAll();

        // result deposit into request domain
        request.setAttribute("Brands", brs);
        // forwarding to jsp
        request.getRequestDispatcher("/allBrand.jsp").forward(request,response);
    }

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

}

执行这个servlet需要先准备相应查询语句和方法
在BrandMapper接口中添加方法，因为java命名时驼峰模式，而数据库查询到的名字有下划线隔断，所以加上第二个注解

package com.diy.mapper;

import com.diy.pojo.Brand;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface BrandMapper {

    /**
     * query all brand info and display to user
     */
    @Select("select * from mybatis.brand")
    @ResultMap("BrandResultMap")// for resolve the brand_name with brandName problem
    List<Brand> selectAll();

}

针对@ResultMap注解，必须在如图路径的sql映射文件中
请添加图片描述
加上相应的标签

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

    <!--resolve the brand_name with brandName problem, type is the table name in database-->
    <resultMap id="BrandResultMap" type="brand">
        <result column="brand_name" property="brandName"></result>
        <result column="company_name" property="companyName"></result>
    </resultMap>

</mapper>

映射文件和接口代理准备完毕后，准备服务类

package com.diy.service;

import com.diy.mapper.BrandMapper;
import com.diy.pojo.Brand;
import com.diy.util.SqlSessFactUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.List;

public class BrandService {

    /**
     * create a sql factory here as a static resource
     */
    SqlSessionFactory ssf = SqlSessFactUtils.getSsf();

    public List<Brand> selectAll(){
        //get session
        SqlSession sqlSession = ssf.openSession();

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

        //through mapper invoke the real selectAll method
        List<Brand> brands = mapper.selectAll();

        sqlSession.close();

        return brands;
    }
}

查询所有的servlet执行完毕会将查询到的数据库数据通过request域对象转发给jsp页面

本jsp中已经包含后续添加功能所需的script代码，和修改，删除的标签完整属性值
实际这部分内容是后续编码中才写入

<%--
  Created by IntelliJ IDEA.
  User: you
  Date: 2022/07/15
  Time: 15:12
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
    <title>All Brand</title>
</head>
<body>

<input type="button" id="add" value="Add New"><br>
<hr>
<table border="1" cellspacing="0" width="1000">
    <tr>
        <th>NO.</th>
        <th>Brand Name</th>
        <th>Company Name</th>
        <th>Ordered</th>
        <th>Description</th>
        <th>Status</th>
        <th>Operation</th>
    </tr>

    <c:forEach items="${Brands}" var="brand" varStatus="id">
        <tr align="center">
                <%--<td>${brand.id}</td>--%>
                <%--<td>${id.index}</td>--%>
            <td>${id.count}</td>
            <td>${brand.brandName}</td>
            <td>${brand.companyName}</td>
            <td>${brand.ordered}</td>
            <td>${brand.description}</td>
            <c:if test="${brand.status == 1}">
                <td>Enable</td>
            </c:if>
            <c:if test="${brand.status == 0}">
                <td>Disable</td>
            </c:if>
                <%--<td>${brand.status}</td>--%>

            <td>
                <a href="/MVC_Demo/selectByIdServlet?id=${brand.id}">Edit</a>
                <a href="/MVC_Demo/deleteByIdServlet?id=${brand.id}" onclick="return confirm('确认删除吗？')">Delete</a>
            </td>
        </tr>
    </c:forEach>
</table>
<hr>
<c:forEach begin="1" end="10" step="1" var="i">
    <a href="#">${i}</a>
</c:forEach>

<script>
    document.getElementById("add").onclick = function (){
        location.href="/MVC_Demo/addNew.jsp"
    }

</script>

</body>
</html>

首次访问的效果图
请添加图片描述
如果没加@ResultMap的注解，此处品牌名和公司名会显示为空，因从数据库来的数据列名对不上java的Brand类的成员变量名
请添加图片描述
左下角选页的超链接与本例无关，是之前案例遗留代码，懒得删除了

文章目录


添加操作
首先代理接口添加方法，之前的BrandMapper变为

package com.diy.mapper;

import com.diy.pojo.Brand;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface BrandMapper {

    /**
     * query all brand info and display to user
     */
    @Select("select * from mybatis.brand")
    @ResultMap("BrandResultMap")// for resolve the brand_name with brandName problem
    List<Brand> selectAll();

    @Insert("insert into mybatis.brand values (null, #{brandName},#{companyName},#{ordered},#{description},#{status})")
    void add(Brand brand);
}

BrandService类也相应添加方法，累加后变成

package com.diy.service;

import com.diy.mapper.BrandMapper;
import com.diy.pojo.Brand;
import com.diy.util.SqlSessFactUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.List;

public class BrandService {

    /**
     * create a sql factory here as a static resource
     */
    SqlSessionFactory ssf = SqlSessFactUtils.getSsf();

    public List<Brand> selectAll(){
        //get session
        SqlSession sqlSession = ssf.openSession();

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

        //through mapper invoke the real selectAll method
        List<Brand> brands = mapper.selectAll();

        sqlSession.close();

        return brands;
    }

    public void add(Brand br){
        //get session
        SqlSession sess = ssf.openSession();

        //get mapper
        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        //use mapper method
        mpe.add(br);

        sess.commit();

        sess.close();

    }
}

之前的显示所有品牌的jsp中有添加Add New按钮，和相应JavaScript代码，点击添加会转到添加的jsp页面

<%--
  Created by IntelliJ IDEA.
  User: you
  Date: 2022/07/15
  Time: 15:52
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Add New Brand</title>
</head>
<body>
    <form action="/MVC_Demo/AddBrandServlet" method="post">
        Brand Name:<input name="brandName"><br>
        Company Name:<input name="companyName"><br>
        Ordered:<input name="ordered"><br>
        Description:<textarea rows="5" cols="20" name="description"></textarea><br>
        Status:
        <input type="radio" name="status" value="0">Disable
        <input type="radio" name="status" value="1">Enable<br>
        <input type="submit" value="sub">
    </form>
</body>
</html>

请添加图片描述
截这张图时还没有调整描述信息文本框的大小，本页填完，提交给AddBrandServlet类

package com.diy.web;

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;

@WebServlet("/AddBrandServlet")
public class AddBrandServlet extends HttpServlet {

    private BrandService bse = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // solve garbled char problem first
        request.setCharacterEncoding("utf-8");

        //get a brand object submitted by user
        String brandName = request.getParameter("brandName");
        String companyName = request.getParameter("companyName");
        String ordered = request.getParameter("ordered");
        String description = request.getParameter("description");
        String status = request.getParameter("status");

        Brand br = new Brand();
        br.setBrandName(brandName);
        br.setCompanyName(companyName);
        br.setOrdered(Integer.parseInt(ordered));
        br.setDescription(description);
        br.setStatus(Integer.parseInt(status));

        // invoke by service object
        bse.add(br);

        //forwarding to all brand info page
        request.getRequestDispatcher("/selectAllServlet").forward(request,response);
    }

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

这个servlet执行完又转发到查询所有的servlet，查询所有的servlet又再次查询过，立刻跳到显示全部的jsp，效果就是点击提交后，立刻就看到新添加的表项了，但是
请添加图片描述
新提交的显示为乱码，因为网页提交过去的中文，后台解析成乱码了，数据库接收到的就是乱码
请添加图片描述

所以我们在之前执行添加的servlet中补上了解决乱码的一句

request.setCharacterEncoding("utf-8");

之前的乱码表项不删除，直接重新提交
请添加图片描述

文章目录


修改操作
修改操作首先，进入修改页面，要看得见该表项的数据，所以这个jsp要根据id查询相应品牌信息并回显
注意品牌的id是数据库主键，在网页不显示，属于隐藏数据，在上图页面，鼠标停留在修改栏，可以在浏览器左下角看到对应 id值，截图省略了
一，实现回显
点击编辑后，会请求到对应servlet，这个servlet要根据id查询数据并传给修改的jsp，执行这个servlet之前，要如下准备
BrandMapper接口类添加方法，累加如下，注意这里也要@ResultMap

package com.diy.mapper;

import com.diy.pojo.Brand;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface BrandMapper {

    /**
     * query all brand info and display to user
     */
    @Select("select * from mybatis.brand")
    @ResultMap("BrandResultMap")// for resolve the brand_name with brandName problem
    List<Brand> selectAll();

    @Insert("insert into mybatis.brand values (null, #{brandName},#{companyName},#{ordered},#{description},#{status})")
    void add(Brand brand);

    /**
     * here is for edit time, display the info of brand will be edited
     */
    @Select("select * from mybatis.brand where id = #{id}")
    @ResultMap("BrandResultMap")
    Brand selectById(int id);
}

BrandService类相应添加方法，累加如下

package com.diy.service;

import com.diy.mapper.BrandMapper;
import com.diy.pojo.Brand;
import com.diy.util.SqlSessFactUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.List;

public class BrandService {

    /**
     * create a sql factory here as a static resource
     */
    SqlSessionFactory ssf = SqlSessFactUtils.getSsf();

    public List<Brand> selectAll(){
        //get session
        SqlSession sqlSession = ssf.openSession();

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

        //through mapper invoke the real selectAll method
        List<Brand> brands = mapper.selectAll();

        sqlSession.close();

        return brands;
    }

    public void add(Brand br){
        //get session
        SqlSession sess = ssf.openSession();

        //get mapper
        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        //use mapper method
        mpe.add(br);

        sess.commit();

        sess.close();

    }

    public Brand selectById(int id) {
        SqlSession sess = ssf.openSession();

        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        Brand br = mpe.selectById(id);

        sess.close();

        return br;
    }
}

servlet类如下

package com.diy.web;

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;

@WebServlet("/selectByIdServlet")
public class SelectByIdServlet extends HttpServlet {

    private BrandService bse = new BrandService();
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //receive brand id
        String id = request.getParameter("id");

        //query by id get the brand
        Brand br = bse.selectById(Integer.parseInt(id));

        //deposit brand into edit jsp
        request.setAttribute("brand",br);

        //forward to that jsp
        request.getRequestDispatcher("/editBrand.jsp").forward(request,response);

    }

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

这个servlet转到编辑页的jsp，输入框例已经有现有值的回显，隐藏数据，也就是id会自动提交

<%--
  Created by IntelliJ IDEA.
  User: you
  Date: 2022/07/15
  Time: 16:50
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
    <title>Edit Brand Info</title>
</head>
<body>
<form action="/MVC_Demo/updateServlet" method="post">

    <input type="hidden" name="id" value="${brand.id}">

    Brand Name:<input name="brandName" value="${brand.brandName}"><br>
    Company Name:<input name="companyName" value="${brand.companyName}"><br>
    Ordered:<input name="ordered" value="${brand.ordered}"><br>
    Description:<textarea rows="5" cols="20" name="description">${brand.description}</textarea><br>
    Status:
    <c:if test="${brand.status == 1}">
        <input type="radio" name="status" value="0">Disable
        <input type="radio" name="status" value="1" checked>Enable<br>
    </c:if>
    <c:if test="${brand.status == 0}">
        <input type="radio" name="status" value="0" checked>Disable
        <input type="radio" name="status" value="1">Enable<br>
    </c:if>
    <input type="submit" value="Submit">
</form>
</body>
</html>

此处我修改了之前乱码的一项
请添加图片描述
请添加图片描述
上面的jsp页面提交会交给updateServlet处理，这个servlet就要update数据库里的表项了
执行它需要首先
BrandMapper，添加方法，累加如下

package com.diy.mapper;

import com.diy.pojo.Brand;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface BrandMapper {

    /**
     * query all brand info and display to user
     */
    @Select("select * from mybatis.brand")
    @ResultMap("BrandResultMap")// for resolve the brand_name with brandName problem
    List<Brand> selectAll();

    @Insert("insert into mybatis.brand values (null, #{brandName},#{companyName},#{ordered},#{description},#{status})")
    void add(Brand brand);

    /**
     * here is for edit time, display the info of brand will be edited
     */
    @Select("select * from mybatis.brand where id = #{id}")
    @ResultMap("BrandResultMap")
    Brand selectById(int id);

    @Update("update mybatis.brand set brand_name = #{brandName}, company_name = #{companyName},ordered = #{ordered}, description = #{description}, status = #{status} where id = #{id}")
    void update(Brand brand);
}

BrandService类也要对应，累加如下

package com.diy.service;

import com.diy.mapper.BrandMapper;
import com.diy.pojo.Brand;
import com.diy.util.SqlSessFactUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.List;

public class BrandService {

    /**
     * create a sql factory here as a static resource
     */
    SqlSessionFactory ssf = SqlSessFactUtils.getSsf();

    public List<Brand> selectAll(){
        //get session
        SqlSession sqlSession = ssf.openSession();

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

        //through mapper invoke the real selectAll method
        List<Brand> brands = mapper.selectAll();

        sqlSession.close();

        return brands;
    }

    public void add(Brand br){
        //get session
        SqlSession sess = ssf.openSession();

        //get mapper
        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        //use mapper method
        mpe.add(br);

        sess.commit();

        sess.close();

    }

    public Brand selectById(int id) {
        SqlSession sess = ssf.openSession();

        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        Brand br = mpe.selectById(id);

        sess.close();

        return br;
    }

    public void update(Brand brand){
        SqlSession sess = ssf.openSession();

        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        mpe.update(brand);

        sess.commit();

        sess.close();
    }
}

然后servlet如下，注意也要应对乱码问题

package com.diy.web;

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;

@WebServlet("/updateServlet")
public class UpdateServlet extends HttpServlet {

    private BrandService bse = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // solve garbled char problem first
        request.setCharacterEncoding("utf-8");

        //get a brand object submitted by user
        String id = request.getParameter("id");
        String brandName = request.getParameter("brandName");
        String companyName = request.getParameter("companyName");
        String ordered = request.getParameter("ordered");
        String description = request.getParameter("description");
        String status = request.getParameter("status");

        Brand br = new Brand();
        br.setId(Integer.parseInt(id));
        br.setBrandName(brandName);
        br.setCompanyName(companyName);
        br.setOrdered(Integer.parseInt(ordered));
        br.setDescription(description);
        br.setStatus(Integer.parseInt(status));

        bse.update(br);

        request.getRequestDispatcher("/selectAllServlet").forward(request,response);

    }

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

这个servlet执行完毕后会转到查询全部的servlet，查询全部的servlet就会再次查询，得到更新后的全部信息，转到显示全部的jsp
请添加图片描述
请添加图片描述

文章目录


删除操作
删除操作直接删除后显示全部表项，由于速度太快，观感不好，所以按照现有知识点，添加了一个跳转提示的页面，但也没能完美解决，
需要手动点alert弹出框之后，才会触发等待3000毫秒跳转的效果
要让alert自动关闭，超纲，且代码增多过度，所以本次放弃，将就了

BrandMapper累加如下，最后形态

package com.diy.mapper;

import com.diy.pojo.Brand;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface BrandMapper {

    /**
     * query all brand info and display to user
     */
    @Select("select * from mybatis.brand")
    @ResultMap("BrandResultMap")// for resolve the brand_name with brandName problem
    List<Brand> selectAll();

    @Insert("insert into mybatis.brand values (null, #{brandName},#{companyName},#{ordered},#{description},#{status})")
    void add(Brand brand);

    /**
     * here is for edit time, display the info of brand will be edited
     */
    @Select("select * from mybatis.brand where id = #{id}")
    @ResultMap("BrandResultMap")
    Brand selectById(int id);

    @Update("update mybatis.brand set brand_name = #{brandName}, company_name = #{companyName},ordered = #{ordered}, description = #{description}, status = #{status} where id = #{id}")
    void update(Brand brand);

    @Delete("delete from mybatis.brand where id = #{id}")
    void deleteById(int id);

}

BrandService最后形态

package com.diy.service;

import com.diy.mapper.BrandMapper;
import com.diy.pojo.Brand;
import com.diy.util.SqlSessFactUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.List;

public class BrandService {

    /**
     * create a sql factory here as a static resource
     */
    SqlSessionFactory ssf = SqlSessFactUtils.getSsf();

    public List<Brand> selectAll(){
        //get session
        SqlSession sqlSession = ssf.openSession();

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

        //through mapper invoke the real selectAll method
        List<Brand> brands = mapper.selectAll();

        sqlSession.close();

        return brands;
    }

    public void add(Brand br){
        //get session
        SqlSession sess = ssf.openSession();

        //get mapper
        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        //use mapper method
        mpe.add(br);

        sess.commit();

        sess.close();

    }

    public Brand selectById(int id) {
        SqlSession sess = ssf.openSession();

        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        Brand br = mpe.selectById(id);

        sess.close();

        return br;
    }

    public void update(Brand brand){
        SqlSession sess = ssf.openSession();

        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        mpe.update(brand);

        sess.commit();

        sess.close();
    }

    public void deleteById(int id){
        SqlSession sess = ssf.openSession();

        BrandMapper mpe = sess.getMapper(BrandMapper.class);

        mpe.deleteById(id);

        sess.commit();

        sess.close();
    }

}

在显示全表信息的jsp页，点击delete超链接会弹出确认框请添加图片描述
为了试验代码，已经删除添加多次了，所以现在数据就变成上图了，点击ok之后会提交给删除对应的servlet

package com.diy.web;

import com.diy.service.BrandService;

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

@WebServlet("/deleteByIdServlet")
public class DeleteByIdServlet extends HttpServlet {
    private BrandService bse = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //receive brand id
        String id = request.getParameter("id");

        //invoke service and delete
        bse.deleteById(Integer.parseInt(id));

        //jump to allBrand page
        request.getRequestDispatcher("/afterDelete.jsp").forward(request,response);
    }

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

这个servlet执行完删除后会转到一个跳转效果的jsp

<%--
  Created by IntelliJ IDEA.
  User: you
  Date: 2022/07/15
  Time: 22:02
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Transiting...</title>

</head>
<body>
    <script>
        alert("Deleting data for you...")
        // setTimeout(function (){
        // }, 3000)
        setTimeout("window.location.href = 'index.html'", 3000)
    </script>
</body>
</html>

这个跳转页点击过alert弹出框，不点不会自动关闭，目前放弃解决这个问题，等3000毫秒会跳转到项目的默认访问页，最初的index.html
请添加图片描述
也就是这个
请添加图片描述
点进去
请添加图片描述
王司徒已经被删除了
请添加图片描述

全文完

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