JSP快速入门（案例:增删改查回显）

编程语言 2023-06-05 21:24:44 阅读次数: 0

目录

一、JSP概述

二、JSP快速入门

​ 三、JSP原理

​四、JSP脚本

五、 JSP缺点

六、EL表达式

七、JSTL标签

 八、MVC模式和三层架构

九、案例练习

9.1 环境准备

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9.2 查询所有

 9.3 添加数据

9.4 回显数据

9.5 修改数据

9.6 删除数据

一、JSP概述

二、JSP快速入门

 三、JSP原理

四、JSP脚本

五、 JSP缺点

六、EL表达式

七、JSTL标签

C标签： 

 

 八、MVC模式和三层架构

 MVC模式：

 三层架构：

 两者之间的关系：

九、案例练习

9.1 环境准备

引坐标：

 <packaging>war</packaging>
 

    <!--依赖-->
    <dependencies>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>

        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.34</version>
        </dependency>

        <!--servlet-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <!--jsp-->
        <dependency>
            <groupId>org.glassfish.web</groupId>
            <artifactId>jsp</artifactId>
            <version>2.2</version>
            <scope>provided</scope>
        </dependency>

        <!--jstl-->
        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <!--standard库-->
        <dependency>
            <groupId>taglibs</groupId>
            <artifactId>standard</artifactId>
            <version>1.1.2</version>
        </dependency>

    </dependencies>


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

 创建三层架构的包结构：

 Mybatis基础环境：

Mybatis-config.xml

<?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>
    <!--起别名-->
    <typeAliases>
        <package name="com.itheima.pojo"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///db1?useSSL=false&amp;useServerPrepStmts=true"/>
                <property name="username" value="root"/>
                <property name="password" value=""/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--扫描mapper-->
        <package name="com.itheima.mapper"/>
    </mappers>
</configuration>

BrandMapper.xml

<?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.itheima.mapper.BrandMapper">

</mapper>

BrandMapper接口：

package com.itheima.mapper;

public interface BrandMapper {
    
}

9.2 查询所有

Mapper接口(Dao层):

   /**
     * 查询所有
     * @return
     */
    @Select("select * from tb_brand")
//    @ResultMap("brandResultMap")
    List<Brand> selectAll();

Service层: 

        //1.获取SqlSessionFactory对象
        SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();
        //2.获取SqlSession对象
        SqlSession sqlSession = factory.openSession();

        //3.获取BrandMapper对象
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4.调用方法
        List<Brand> brands = mapper.selectAll();

        //5.关闭资源
        sqlSession.close();

        return brands;

 Web层:

@WebServlet("/selectAllServlet")
public class SelectAllServlet extends HttpServlet {

    private  BrandService service = new BrandService();
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //1.调用BrandService查询数据,并封装为List对象

        List<Brand> brands = service.selectAll();

        //2.将数据存到request域中
        request.setAttribute("brands",brands);

        //3.转发到brand.jsp
        request.getRequestDispatcher("/brand.jsp").forward(request,response);

    }

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

注意:

在BrandMapper.xml里 设置resultMap来解决数据库和java的名称命名不一致,即映射属性名和数据库中的字段名

在mapper接口中记得添加注解使用 

另一种方法:在mybatis-config.xml中设置

    <!--开启驼峰命名自动映射-->
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>

 9.3 添加数据

Mapper接口(Dao层): 

    @Insert("insert into tb_brand values(null,#{brandName},#{companyName},#{ordered},#{description},#{status})")
//    @ResultMap("brandResultMap")
    void add(Brand brand);

 Service层:

     /**
     * 添加
     * @param brand
     */
    public  void add(Brand brand){
        //1.获取SqlSessionFactory对象
        SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();

        //2.获取sqlSession对象
        SqlSession sqlSession = factory.openSession();

        //3.获取BrandMapper对象
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4.调用方法
        mapper.add(brand);

        //5.增删改需要提交事务
        sqlSession.commit();

        //6.释放资源
        sqlSession.close();

Web层:

@WebServlet("/addServlet")
public class AddServlet extends HttpServlet {

    private BrandService service = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //解决Post中文乱码问题
        request.setCharacterEncoding("utf-8");
        //1.接受表单提交的数据并将其封装为一个Brand对象
        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");

        //封装为Brand对象
        Brand brand = new Brand();
        brand.setBrandName(brandName);
        brand.setCompanyName(companyName);
        brand.setOrdered(Integer.parseInt(ordered));//将字符类型转为Int类型
        brand.setDescription(description);
        brand.setStatus(Integer.parseInt(status));

        //2.调用service完成添加操作
        service.add(brand);

        //3.转发到查询所有Servlet
        request.getRequestDispatcher("/selectAllServlet").forward(request,response);


    }

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

注意:

中文乱码问题:post请求只需要在AddServlet中添加一行代码

  //解决Post中文乱码问题
  request.setCharacterEncoding("utf-8");

MySQL中增删改操作需要提交事务

可以在获取sqlSession对象设置为自动提交:

//2.获取sqlSession对象
SqlSession sqlSession = factory.openSession(true);

也可以手动提交:

     //5.增删改需要提交事务
        sqlSession.commit();

9.4 回显数据

Mapper接口(Dao层):

    /**
     * 根据id查询
     * @param id
     * @return
     */
    @Select("select * from tb_brand where id = #{id}")
    Brand selectById(int id);

Service层:

    /**
     * 根据id查询
     * @param id
     * @return
     */
    public Brand selectById(int id){
        //调用BrandselectAll()

        //1.获取SqlSessionFactory对象
        SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();

        //2.获取SqlSession对象
        SqlSession sqlSession = factory.openSession();

        //3.获取BrandMapper对象
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4.调用方法
        Brand brand = mapper.selectById(id);

        //5.关闭资源
        sqlSession.close();

        return brand;

    }

Web层:

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

    private  BrandService service = new BrandService();
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //1.接受id
        String id = request.getParameter("id");

        //2.调用Service查询
        Brand brand = service.selectById(Integer.parseInt(id));

        //3.存储到request域中
        request.setAttribute("brand", brand);

        //4.转发到update.jsp中
        request.getRequestDispatcher("/update.jsp").forward(request, response);



    }

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

9.5 修改数据

Mapper接口(Dao层):

     /**
     * 修改操作
     * @param brand
     */
    @Update("update tb_brand set brand_name = #{brandName}," +
            "                    company_name = #{companyName}," +
            "                    ordered = #{ordered}," +
            "                    description = #{description}," +
            "                    status = #{status} " +
            "                    where id = #{id}")
    void update(Brand brand);

 Service层:

     /**
     * 修改
     * @param brand
     */
    public  void update(Brand brand){

        //1.获取SqlSessionFactory对象
        SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();

        //2.获取sqlSession对象
        SqlSession sqlSession = factory.openSession();

        //3.获取BrandMapper对象
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4.调用方法
        mapper.update(brand);

        //5.增删改需要提交事务
        sqlSession.commit();

        //6.释放资源
        sqlSession.close();
    }

 Web层:

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

    private BrandService service = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //解决Post中文乱码问题
        request.setCharacterEncoding("utf-8");
        //1.接受表单提交的数据并将其封装为一个Brand对象
        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");


        //封装为Brand对象
        Brand brand = new Brand();
        brand.setId(Integer.parseInt(id));
        brand.setBrandName(brandName);
        brand.setCompanyName(companyName);
        brand.setOrdered(Integer.parseInt(ordered));//将字符类型转为Int类型
        brand.setDescription(description);
        brand.setStatus(Integer.parseInt(status));

        //2.调用service完成修改操作
        service.update(brand);

        //3.转发到查询所有Servlet
        request.getRequestDispatcher("/selectAllServlet").forward(request,response);


    }

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

brand.jsp: 

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html lang="en">


<head>
    <meta charset="UTF-8">
    <title>修改品牌</title>

</head>
<body>
<h3>修改品牌</h3>
<form action="/brand-demo/updateServlet" method="post">

    <%--隐藏域提交id--%>
    <input type="hidden" name="id" value="${brand.id}">

    品牌名称：<input name="brandName" value="${brand.brandName}"><br>
    企业名称：<input name="companyName" value="${brand.companyName}"><br>
    排序：<input name="ordered" value="${brand.ordered}"><br>
    描述信息：<textarea rows="5" cols="20" name="description" >${brand.description}</textarea><br>
    状态：
    <c:if test="${brand.status == 0}">
        <input type="radio" name="status" value="0" checked>禁用
        <input type="radio" name="status" value="1">启用<br>
    </c:if>
    <c:if test="${brand.status == 1}">
        <input type="radio" name="status" value="0" >禁用
        <input type="radio" name="status" value="1" checked>启用<br>
    </c:if>


    <input type="submit" value="提交">
</form>
</body>
</html>

注意:

处理"启用/禁用"状态时使用<c>标签,需要在头部引入

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

通过隐藏域将id传到Servlet中

 <%--隐藏域提交id--%>
 <input type="hidden" name="id" value="${brand.id}">

9.6 删除数据

Mapper接口(Dao层):

    /**
     * 删除
     * @param id
     */
    @Delete("delete from tb_brand where id = #{id}")
    void deleteById(int id);

Service层:

 /**
     * 根据id删除
     * @param id
     */
    public void deleteById(int id){
        //调用BrandselectAll()

        //2.获取SqlSession对象
        SqlSession sqlSession = factory.openSession();

        //3.获取BrandMapper对象
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);

        //4.调用方法
        mapper.deleteById(id);

        //5.提交事务
        sqlSession.commit();

        //6.关闭资源
        sqlSession.close();

    }

Web层:

@WebServlet("/deleteByIdServlet")
public class DeleteByIdServlet extends HttpServlet {

    private BrandService service = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //解决Post中文乱码问题
        request.setCharacterEncoding("utf-8");
        //1.接受表单提交的数据获取id
        String id = request.getParameter("id");

        //2.调用service完成修改操作
        service.deleteById(Integer.parseInt(id));

        //3.转发到查询所有Servlet
        request.getRequestDispatcher("/selectAllServlet").forward(request,response);


    }

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

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