JSP快速入门（案例:增删改查回显）

谁践踏了优雅 2024-03-27 11:06 78阅读 0赞

**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

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 ##

![207b4ad794e545c0a9b5c4f0c913b387.png][]

## 二、JSP快速入门 ##

## ![a4520bd176ee471da83104f5f8531f26.png][] 三、JSP原理 ##

## ![88525d2ce56945e69231743fff62fdf8.png][]四、JSP脚本 ##

![192e07516b494c7085eac4c101c01cfc.png][]

## 五、 JSP缺点 ##

![d10eb5097ddb44b686dad2aea255a348.png][]

## 六、EL表达式 ##

## ![df751440d0ca42c8a7cbc3e74cd098db.png][] ##

## 七、JSTL标签 ##

![e63703fc04bc4d91a20e3c0112ebccc7.png][]

**C标签：**

![9a97414e7582417c8893105ff812e7e5.png][] ![66f8d16eb81645dc84a67dae196a800f.png][]

## 八、MVC模式和三层架构 ##

MVC模式：![bf5ab4b22ab948d185ba9d5c56b20d17.png][]

三层架构：

![83bbc76be5c24186a5df69241d7da785.png][]

两者之间的关系：

![be3aee27afac4c82942085e43dd6fefd.png][]

## 九、案例练习 ##

### 9.1 环境准备 ###

![4eec07db4a7646569a1a14a49abb114f.png][]

引坐标：

<packaging>war</packaging>
     
    
        
        <dependencies>
            
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.5.5</version>
            </dependency>
    
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.34</version>
            </dependency>
    
            
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>javax.servlet-api</artifactId>
                <version>3.1.0</version>
                <scope>provided</scope>
            </dependency>
    
            
            <dependency>
                <groupId>org.glassfish.web</groupId>
                <artifactId>jsp</artifactId>
                <version>2.2</version>
                <scope>provided</scope>
            </dependency>
    
            
            <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>

创建三层架构的包结构：

![d8d712b395374a278c475e381582140c.png][]

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>
        
        <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&useServerPrepStmts=true"/>
                    <property name="username" value="root"/>
                    <property name="password" value=""/>
                </dataSource>
            </environment>
        </environments>
        <mappers>
            
            <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 ###

![49b9d6cc185d4152a4768997fca86e3e.png][]

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

![1a502ed9e08f42458b309d1ecc108b49.png][]

在mapper接口中记得添加注解使用

![287bf4d3730c4e8e9040fde5438caeed.png][]

另一种方法:在mybatis-config.xml中设置

<settings>
            <setting name="mapUnderscoreToCamelCase" value="true"/>
        </settings>

### 9.3 添加数据 ###

![9bc9ba9246664c1ebb48f10c115eee07.png][]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 ###

![59858ffd123a4fa3810f899d23a0748c.png][]

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 ###

![443758164f384d8f881219a2cb9300c1.png][]

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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