11、Javaweb_JSPMVCELJSTL三层架构用户列表案例

JSP:

1. 指令
   * 作用：用于配置JSP页面，导入资源文件
   * 格式：
       <%@ 指令名称属性名1=属性值1 属性名2=属性值2 ... %>
   * 分类：
       1. page       ：配置JSP页面的
           * contentType：等同于response.setContentType()
               1. 设置响应体的mime类型以及字符集
               2. 设置当前jsp页面的编码（只能是高级的IDE才能生效，如果使用低级工具，则需要设置pageEncoding属性设置当前页面的字符集）
           * import：导包
           * errorPage：当前页面发生异常后，会自动跳转到指定的错误页面
           * isErrorPage：标识当前也是是否是错误页面。
               * true：是，可以使用内置对象exception
               * false：否。默认值。不可以使用内置对象exception

发生异常，跳转错误页面

<%@ page import="java.util.ArrayList" %>
<%@ page import="java.util.List" %>
<%@ page contentType="text/html;charset=gbk" errorPage="500.jsp"   pageEncoding="GBK" language="java" buffer="16kb" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
  <%

    List list = new ArrayList();
    int i = 3/0;

  %>
  </body>
</html>

被跳转的错误页面：

<%@ page contentType="text/html;charset=UTF-8" isErrorPage="true" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

    <h1>服务器正忙...</h1>
    <%
        String message = exception.getMessage();
        out.print(message);

    %>
</body>
</html>

2. include   ：页面包含的。导入页面的资源文件
           * <%@include file="top.jsp"%>
       3. taglib   ：导入资源
           * <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
               * prefix：前缀，自定义的
2. 注释:
   1. html注释：
       :只能注释html代码片段,并且注释信息会发送到响应体中
   2. jsp注释：推荐使用
       <%-- --%>：可以注释所有,并且注释信息不回发送到响应体中

导入资源文件

<%@ page contentType="text/html;charset=UTF-8" language="java"  %>
<%@include file="top.jsp"%>
<html>
<head>
    <title>Title</title>
</head>
<body>

    <!--
        <h1>hello</h1>
    -->
    <%--
        <%
            System.out.println("hi~~~~");
        %>
    --%>
<%--

    <input>
--%>
    <%
        pageContext.setAttribute("msg","hello");

    %>
    <%=pageContext.getAttribute("msg")%>

</body>
</html>

被导入资源文件：top.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<h1>页面logo页面标题</h1>

3. 内置对象
   * 在jsp页面中不需要创建，直接使用的对象
//C:\Users\Administrator\AppData\Local\JetBrains\IntelliJIdea2022.3\tomcat\bc4f368a-2989-4a92-9ce4-f5e65d925d89\work\Catalina\localhost\ROOT\org\apache\jsp\_500_jsp.java
   * 一共有9个：
           变量名                   真实类型                       作用
       * pageContext               PageContext                   当前页面共享数据，还可以获取其他八个内置对象
       * request                   HttpServletRequest           一次请求访问的多个资源(转发)
       * session                   HttpSession                   一次会话的多个请求间
       * application               ServletContext               所有用户间共享数据
       * response                   HttpServletResponse           响应对象
       * page                       Object                       当前页面(Servlet)的对象 this
       * out                       JspWriter                   输出对象，数据输出到页面上
       * config                   ServletConfig               Servlet的配置对象
       * exception                   Throwable                   异常对象

MVC：开发模式

1. jsp演变历史
   1. 早期只有servlet，只能使用response输出标签数据，非常麻烦
   2. 后来又jsp，简化了Servlet的开发，如果过度使用jsp，在jsp中即写大量的java代码，有写html表，造成难于维护，难于分工协作
   例如:在jsp中把HTML,CSS，JavaScript,Java代码写在一个页面,并且html嵌套在Java代码中,html还嵌套在for循环中,前端人员不易读懂代码,只有开发人员自己能够维护. 只有开发人员自己写的时候方便,不利于分工协作
   3. 再后来，java的web开发，借鉴mvc开发模式，使得程序的设计更加合理性

2. MVC：
   1. M：Model，模型。JavaBean
       * 完成具体的业务操作，如：查询数据库，封装对象
   2. V：View，视图。JSP
       * 展示数据
   3. C：Controller，控制器。Servlet
       * 获取用户的输入
       * 调用模型
       * 将数据交给视图进行展示

* 优缺点：
       1. 优点：
           1. 耦合性低，方便维护，可以利于分工协作
           2. 重用性高

2. 缺点：
1. 使得项目架构变得复杂，对开发人员要求高

EL表达式

1. 概念：Expression Language 表达式语言
2. 作用：替换和简化jsp页面中java代码的编写
3. 语法：${表达式}
4. 注意：
   * jsp默认支持el表达式的。如果要忽略el表达式
       1. 设置jsp中page指令中：isELIgnored="true" 忽略当前jsp页面中所有的el表达式
       2. \${表达式} ：忽略当前这个el表达式

5. 使用：
   1. 运算：
       * 运算符：
           1. 算数运算符： + - * /(div) %(mod)
           2. 比较运算符： > < >= <= == !=
           3. 逻辑运算符： &&(and) ||(or) !(not)
           4. 空运算符： empty
               * 功能：用于判断字符串、集合、数组对象是否为null或者长度是否为0
               * ${empty list}:判断字符串、集合、数组对象是否为null或者长度为0
               * ${not empty str}:表示判断字符串、集合、数组对象是否不为null 并且长度>0

<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ page contentType="text/html;charset=UTF-8" language="java"   %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    ${3 > 4}

    \${3 > 4}
<hr>
    <h3>算数运算符</h3>
    ${3 + 4}<br>
    ${3 / 4}<br>
    ${3 div 4}<br>
    ${3 % 4}<br>
    ${3 mod 4}<br>
    <h3>比较运算符</h3>
    ${3 == 4}<br>

    <h3>逻辑运算符</h3>
    ${3 > 4  && 3 < 4}<br>
    ${3 > 4  and 3 < 4}<br>
    
    <h4>empty运算符</h4>
<%

    String str = "";
    request.setAttribute("str",str);

    List list = new ArrayList();
    request.setAttribute("list",list);

%>
    ${not empty str}

    ${not empty list}
</body>
</html>

   2. 获取值
       1. el表达式只能从域对象中获取值
       2. 语法：
           1. ${域名称.键名}：从指定域中获取指定键的值
               * 域名称：
                   1. pageScope       --> pageContext
                   2. requestScope    --> request
                   3. sessionScope    --> session
                   4. applicationScope --> application（ServletContext）
               * 举例：在request域中存储了name=张三
               * 获取：${requestScope.name}

2. ${键名}：表示依次从最小的域中查找是否有该键对应的值，直到找到为止。

<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>el获取域中的数据</title>
</head>
<body>


    <%
        //在域中存储数据
        session.setAttribute("name","李四");

        request.setAttribute("name","张三");
        session.setAttribute("age","23");

        request.setAttribute("str","");

    %>

<h3>el获取值</h3>
${requestScope.name}
${sessionScope.age}
${sessionScope.haha}

${name}
${sessionScope.name}




</body>
</html>

    3. 获取对象、List集合、Map集合的值
               1. 对象：${域名称.键名.属性名}
                   * 本质上会去调用对象的getter方法

2. List集合：${域名称.键名[索引]}

               3. Map集合：
                   * ${域名称.键名.key名称}
                   * ${域名称.键名["key名称"]}

<%@ page import="cn.itcast.domain.User" %>
<%@ page import="java.util.*" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>el获取数据</title>
</head>
<body>

    <%
        User user = new User();
        user.setName("张三");
        user.setAge(23);
        user.setBirthday(new Date());


        request.setAttribute("u",user);


        List list = new ArrayList();
        list.add("aaa");
        list.add("bbb");
        list.add(user);

        request.setAttribute("list",list);


        Map map = new HashMap();
        map.put("sname","李四");
        map.put("gender","男");
        map.put("user",user);

        request.setAttribute("map",map);

    %>

<h3>el获取对象中的值</h3>
${requestScope.u}<br>

<%--
    * 通过的是对象的属性来获取
        * setter或getter方法，去掉set或get，在将剩余部分，首字母变为小写。
        * setName --> Name --> name
--%>

    ${requestScope.u.name}<br>
    ${u.age}<br>
    ${u.birthday}<br>
    ${u.birthday.month}<br>

    ${u.birStr}<br>

    <h3>el获取List值</h3>
    ${list}<br>
    ${list[0]}<br>
    ${list[1]}<br>
    ${list[10]}<br>

    ${list[2].name}

    <h3>el获取Map值</h3>
    ${map.gender}<br>
    ${map["gender"]}<br>
    ${map.user.name}

</body>
</html>

3. 隐式对象：
       * el表达式中有11个隐式对象
       * pageContext：
           * 获取jsp其他八个内置对象
               * ${pageContext.request.contextPath}：动态获取虚拟目录

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>el隐式对象</title>
</head>
<body>


    ${pageContext.request}<br>
    <h4>在jsp页面动态获取虚拟目录</h4>
    ${pageContext.request.contextPath}

<%


%>
</body>
</html>

JSTL

1. 概念：JavaServer Pages Tag Library JSP标准标签库
* 是由Apache组织提供的开源的免费的jsp标签 <标签>

2. 作用：用于简化和替换jsp页面上的java代码

3. 使用步骤：
1. 导入jstl相关jar包

jstl-impl.jar
javax.servlet.jsp.jstl.jar

2. 引入标签库：taglib指令： <%@ taglib %>
3. 使用标签

4. 常用的JSTL标签
   1. if:相当于java代码的if语句
       1. 属性：
            * test 必须属性，接受boolean表达式
                * 如果表达式为true，则显示if标签体内容，如果为false，则不显示标签体内容
                * 一般情况下，test属性值会结合el表达式一起使用
        2. 注意：
              * c:if标签没有else情况，想要else情况，则可以在定义一个c:if标签

<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<html>
<head>
    <title>if标签</title>
</head>
<body>

    <%--

    c:if标签
        1. 属性：
            * test 必须属性，接受boolean表达式
                * 如果表达式为true，则显示if标签体内容，如果为false，则不显示标签体内容
                * 一般情况下，test属性值会结合el表达式一起使用

        2. 注意：c:if标签没有else情况，想要else情况，则可以在定义一个c:if标签


    --%>

    <c:if test="true">
        <h1>我是真...</h1>
    </c:if>
    <br>

    <%
        //判断request域中的一个list集合是否为空，如果不为null则显示遍历集合

        List list = new ArrayList();
        list.add("aaaa");
        request.setAttribute("list",list);

        request.setAttribute("number",4);

    %>

    <c:if test="${not empty list}">
        遍历集合...

    </c:if>
    <br>

    <c:if test="${number % 2 != 0}">

            ${number}为奇数

    </c:if>

    <c:if test="${number % 2 == 0}">

        ${number}为偶数

    </c:if>

</body>
</html>

   2. choose:相当于java代码的switch语句
       1. 使用choose标签声明                    相当于switch声明
        2. 使用when标签做判断                    相当于case
        3. 使用otherwise标签做其他情况的声明       相当于default

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

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

<html>
<head>
    <title>choose标签</title>
</head>
<body>

    <%--
        完成数字编号对应星期几案例
            1.域中存储一数字
            2.使用choose标签取出数字         相当于switch声明
            3.使用when标签做数字判断         相当于case
            4.otherwise标签做其他情况的声明  相当于default
    --%>

    <%
        request.setAttribute("number",51);
    %>

    <c:choose>
        <c:when test="${number == 1}">星期一</c:when>
        <c:when test="${number == 2}">星期二</c:when>
        <c:when test="${number == 3}">星期三</c:when>
        <c:when test="${number == 4}">星期四</c:when>
        <c:when test="${number == 5}">星期五</c:when>
        <c:when test="${number == 6}">星期六</c:when>
        <c:when test="${number == 7}">星期天</c:when>

        <c:otherwise>数字输入有误</c:otherwise>
    </c:choose>


</body>
</html>

3. foreach:相当于java代码的for语句

<%@ page import="java.util.ArrayList" %>
<%@ page import="java.util.List" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>

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

<html>
<head>
    <title>foreach标签</title>
</head>
<body>

<%--

    foreach:相当于java代码的for语句
        1. 完成重复的操作
            for(int i = 0; i < 10; i ++){

            }
            * 属性：
                begin：开始值
                end：结束值
                var：临时变量
                step：步长
                varStatus:循环状态对象
                    index:容器中元素的索引，从0开始
                    count:循环次数，从1开始
        2. 遍历容器
            List<User> list;
            for(User user : list){

            }

            * 属性：
                items:容器对象
                var:容器中元素的临时变量
                varStatus:循环状态对象
                    index:容器中元素的索引，从0开始
                    count:循环次数，从1开始


--%>

<c:forEach begin="1" end="10" var="i" step="2" varStatus="s">
    ${i} <h3>${s.index}<h3> <h4> ${s.count} </h4><br>

</c:forEach>

    <hr>


    <%
        List list = new ArrayList();
        list.add("aaa");
        list.add("bbb");
        list.add("ccc");

        request.setAttribute("list",list);


    %>

    <c:forEach items="${list}" var="str" varStatus="s">

            ${s.index} ${s.count} ${str}<br>

    </c:forEach>


</body>
</html>

5. 练习：
* 需求：在request域中有一个存有User对象的List集合。需要使用jstl+el将list集合数据展示到jsp页面的表格table中

<%@ page import="cn.itcast.domain.User" %>
<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ page import="java.util.Date" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<html>
<head>
    <title>test</title>
</head>
<body>

<%

    List list = new ArrayList();
    list.add(new User("张三",23,new Date()));
    list.add(new User("李四",24,new Date()));
    list.add(new User("王五",25,new Date()));

    request.setAttribute("list",list);


%>

<table border="1" width="500" align="center">
    <tr>
        <th>编号</th>
        <th>姓名</th>
        <th>年龄</th>
        <th>生日</th>
    </tr>
    <%--数据行--%>
    <c:forEach items="${list}" var="user" varStatus="s">

        <c:if test="${s.count % 2 != 0}">

            <tr bgcolor="red">
                <td>${s.count}</td>
                <td>${user.name}</td>
                <td>${user.age}</td>
                <td>${user.birStr}</td>
            </tr>
        </c:if>

        <c:if test="${s.count % 2 == 0}">

            <tr  bgcolor="green">
                <td>${s.count}</td>
                <td>${user.name}</td>
                <td>${user.age}</td>
                <td>${user.birStr}</td>
            </tr>
        </c:if>




    </c:forEach>

</table>






</body>
</html>

三层架构：软件设计架构

1. 界面层(表示层)：用户看的得界面。用户可以通过界面上的组件和服务器进行交互
2. 业务逻辑层：处理业务逻辑的。
3. 数据访问层：操作数据存储文件。

案例：用户信息列表展示

1. 需求：用户信息的增删改查操作

导入包

bootstrap.css
bootstrap-theme.css
bootstrap.js
bootstrap.min.js
jquery-2.1.0.min.js

glyphicons-halflings-regular.eot
glyphicons-halflings-regular.svg
glyphicons-halflings-regular.ttf
glyphicons-halflings-regular.woff
glyphicons-halflings-regular.woff2

导入jar包
spring-tx-4.2.4.RELEASE.jar
spring-jdbc-4.2.4.RELEASE.jar
spring-core-4.2.4.RELEASE.jar
spring-beans-4.2.4.RELEASE.jar
mysql-connector-java-8.0.18.jar
mysql-connector-java-5.1.18-bin.jar
jstl-impl.jar
javax.servlet.jsp.jstl.jar
druid-1.0.9.jar
commons-logging-1.1.1.jar
commons-beanutils-1.8.3.jar
c3p0-0.9.1.2.jar
2. 设计：
   1. 技术选型：Servlet+JSP+MySQL+JDBCTempleat+Duird+BeanUtilS+tomcat
   2. 数据库设计：
       create database day17; -- 创建数据库
       use day17;                -- 使用数据库

create table user(   -- 创建表
            id int primary key auto_increment,
            name varchar(20) not null,
            gender varchar(5),
            age int,
            address varchar(32),
            qq    varchar(20),
            email varchar(50),
            username varchar(32),
            password varchar(32)
        );

insert into user(name,gender,age,address,qq,email,username,password) values
("张三","男",27,"广东","2345857","123@qq.com","zhangsan","123456"),
("李四","男",37,"北京","23458572","1223@qq.com","lisi","123456"),
("王五","男",29,"上海","2345817","1883@qq.com","wangwu","123456"),
("小七","女",22,"广东","2345257","1111@qq.com","xiaoqi","123456"),
("小九","女",23,"四川","23225257","x666@qq.com","xiaojiu","123456"),
("大九","女",23,"四川","23225257","d666@qq.com","dajiu","123456"),
("三九","女",23,"四川","23225257","s666@qq.com","sanjiu","123456"),
("四九","女",23,"四川","23225257","ss666@qq.com","sijiu","123456"),
("五九","女",23,"四川","23225257","w666@qq.com","wujiu","123456"),
("六九","女",23,"四川","23225257","l666@qq.com","liujiu","123456"),
("七九","女",23,"四川","23225257","q666@qq.com","qijiu","123456"),
("八九","女",23,"四川","23225257","b666@qq.com","bajiu","123456");

3. 开发：
   1. 环境搭建
       1. 创建数据库环境
       2. 创建项目，导入需要的jar包

2. 编码

4. 测试
5. 部署运维

视图资源

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="utf-8"/>
  <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
  <meta name="viewport" content="width=device-width, initial-scale=1"/>
  <title>首页</title>

  <!-- 1. 导入CSS的全局样式 -->
  <link href="css/bootstrap.min.css" rel="stylesheet">
  <!-- 2. jQuery导入，建议使用1.9以上的版本 -->
  <script src="js/jquery-2.1.0.min.js"></script>
  <!-- 3. 导入bootstrap的js文件 -->
  <script src="js/bootstrap.min.js"></script>
  <script type="text/javascript">
  </script>
</head>
<body>
<div align="center">
  <a
          href="${pageContext.request.contextPath}/userListServlet" style="text-decoration:none;font-size:33px">查询所有用户信息
  </a>
</div>
</body>
</html>

list.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

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

<!DOCTYPE html>
<!-- 网页使用的语言 -->
<html lang="zh-CN">
<head>
    <!-- 指定字符集 -->
    <meta charset="utf-8">
    <!-- 使用Edge最新的浏览器的渲染方式 -->
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <!-- viewport视口：网页可以根据设置的宽度自动进行适配，在浏览器的内部虚拟一个容器，容器的宽度与设备的宽度相同。
    width: 默认宽度与设备的宽度相同
    initial-scale: 初始的缩放比，为1:1 -->
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ -->
    <title>用户信息管理系统</title>

    <!-- 1. 导入CSS的全局样式 -->
    <link href="css/bootstrap.min.css" rel="stylesheet">
    <!-- 2. jQuery导入，建议使用1.9以上的版本 -->
    <script src="js/jquery-2.1.0.min.js"></script>
    <!-- 3. 导入bootstrap的js文件 -->
    <script src="js/bootstrap.min.js"></script>
    <style type="text/css">
        td, th {
            text-align: center;
        }
    </style>
</head>
<body>
<div class="container">
    <h3 style="text-align: center">用户信息列表</h3>
    <table border="1" class="table table-bordered table-hover">
        <tr class="success">
            <th>编号</th>
            <th>姓名</th>
            <th>性别</th>
            <th>年龄</th>
            <th>籍贯</th>
            <th>QQ</th>
            <th>邮箱</th>
            <th>操作</th>
        </tr>

        <c:forEach items="${users}" var="user" varStatus="s">
            <tr>
                <td>${s.count}</td>
                <td>${user.name}</td>
                <td>${user.gender}</td>
                <td>${user.age}</td>
                <td>${user.address}</td>
                <td>${user.qq}</td>
                <td>${user.email}</td>
<%--                <td><a class="btn btn-default btn-sm" href="update.jsp">修改</a>&nbsp;--%>
                <td><a class="btn btn-default btn-sm" href="${pageContext.request.contextPath}/userFindServlet?name=${user.name}">修改</a>&nbsp;
                    <a class="btn btn-default btn-sm" href="${pageContext.request.contextPath}/userDeleteServlet?name=${user.name}">删除</a></td>
            </tr>

        </c:forEach>


        <tr>
            <td colspan="8" align="center"><a class="btn btn-primary" href="${pageContext.request.contextPath}/add.jsp">添加联系人</a></td>
        </tr>
    </table>
</div>
</body>
</html>

add.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!-- HTML5文档-->
<!DOCTYPE html>
<!-- 网页使用的语言 -->
<html lang="zh-CN">
<head>
    <!-- 指定字符集 -->
    <meta charset="utf-8">
    <!-- 使用Edge最新的浏览器的渲染方式 -->
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <!-- viewport视口：网页可以根据设置的宽度自动进行适配，在浏览器的内部虚拟一个容器，容器的宽度与设备的宽度相同。
    width: 默认宽度与设备的宽度相同
    initial-scale: 初始的缩放比，为1:1 -->
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ -->
    <title>添加用户</title>

    <!-- 1. 导入CSS的全局样式 -->
    <link href="css/bootstrap.min.css" rel="stylesheet">
    <!-- 2. jQuery导入，建议使用1.9以上的版本 -->
    <script src="js/jquery-2.1.0.min.js"></script>
    <!-- 3. 导入bootstrap的js文件 -->
    <script src="js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
    <center><h3>添加联系人页面</h3></center>
    <form action="${pageContext.request.contextPath}/userAddServlet" method="post">
        <div class="form-group">
            <label for="name">姓名：</label>
            <input type="text" class="form-control" id="name" name="name" placeholder="请输入姓名">
        </div>

        <div class="form-group">
            <label>性别：</label>
            <input type="radio" name="gender" value="男" checked="checked"/>男
            <input type="radio" name="gender" value="女"/>女
        </div>

        <div class="form-group">
            <label for="age">年龄：</label>
            <input type="text" class="form-control" id="age" name="age" placeholder="请输入年龄">
        </div>

        <div class="form-group">
            <label for="address">籍贯：</label>
            <select name="address" class="form-control" id="address">
                <option value="广东">广东</option>
                <option value="广西">广西</option>
                <option value="湖南">湖南</option>
            </select>
        </div>

        <div class="form-group">
            <label for="qq">QQ：</label>
            <input type="text" class="form-control" id="qq" name="qq" placeholder="请输入QQ号码"/>
        </div>

        <div class="form-group">
            <label for="email">Email：</label>
            <input type="text" class="form-control" id="email" name="email" placeholder="请输入邮箱地址"/>
        </div>

        <div class="form-group" style="text-align: center">
            <input class="btn btn-primary" type="submit" value="提交" />
            <input class="btn btn-default" type="reset" value="重置" />
            <input class="btn btn-default" type="button" value="返回" />
        </div>
    </form>
</div>
</body>
</html>

update.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<!-- 网页使用的语言 -->
<html lang="zh-CN">
    <head>

<%--    	<base href="<%=basePath%>"/>--%>
        <!-- 指定字符集 -->
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>修改用户</title>

        <link href="css/bootstrap.min.css" rel="stylesheet">
        <script src="js/jquery-2.1.0.min.js"></script>
        <script src="js/bootstrap.min.js"></script>
        
    </head>
    <body>
        <div class="container" style="width: 400px;">
        <h3 style="text-align: center;">修改联系人</h3>
        <form action="${pageContext.request.contextPath}/userUpdateServlet" method="post">
          <div class="form-group">
            <label for="name">姓名：</label>
            <input type="text" class="form-control" id="name" name="name"  readonly="readonly" value="${user.name}" placeholder="${user.name}" />
          </div>

          <div class="form-group">
            <label>性别：</label>
              <input type="radio" name="gender" value="男"    <c:if test="${user.gender=='男'}">checked</c:if>/>男
                <input type="radio" name="gender" value="女" <c:if test="${user.gender=='女'}">checked</c:if> />女
          </div>

          <div class="form-group">
            <label for="age">年龄：</label>
            <input type="text" class="form-control" id="age"  name="age" placeholder="请输入年龄" value="${user.age}" />
          </div>

          <div class="form-group">
            <label for="address">籍贯：</label>
             <select id="address" name="address" class="form-control" >
                <option value="广东">广东</option>
                <option value="广西">广西</option>
                <option value="湖南">湖南</option>
                 <option value="北京">北京</option>
                 <option value="上海">上海</option>
            </select>
          </div>

          <div class="form-group">
            <label for="qq">QQ：</label>
            <input type="text" class="form-control" id="qq" name="qq" placeholder="请输入QQ号码" value="${user.qq}"/>
          </div>

          <div class="form-group">
            <label for="email">Email：</label>
            <input type="text" class="form-control" id="email" name="email" value="${user.email}" placeholder="请输入邮箱地址"/>
          </div>

             <div class="form-group" style="text-align: center">
                <input class="btn btn-primary" type="submit" value="提交" />
                <input class="btn btn-default" type="reset" value="重置" />
                <input class="btn btn-default" type="button" value="返回"/>
             </div>
        </form>
        </div>
    </body>
</html>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="zh-CN">
  <head>
    <meta charset="utf-8"/>
    <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
    <meta name="viewport" content="width=device-width, initial-scale=1"/>
    <title>管理员登录</title>

    <!-- 1. 导入CSS的全局样式 -->
    <link href="css/bootstrap.min.css" rel="stylesheet">
    <!-- 2. jQuery导入，建议使用1.9以上的版本 -->
    <script src="js/jquery-2.1.0.min.js"></script>
    <!-- 3. 导入bootstrap的js文件 -->
    <script src="js/bootstrap.min.js"></script>
    <script type="text/javascript">
    </script>
  </head>
  <body>
  <script>
        window.onload = function(){
            document.getElementById("img").onclick = function(){
                this.src="${pageContext.request.contextPath}/checkCodeServlet?time="+new Date().getTime();
            }
        }


    </script>
  	<div class="container" style="width: 400px;">
  		<h3 style="text-align: center;">管理员登录</h3>
        <form action="${pageContext.request.contextPath}/loginServlet" method="post">
	      <div class="form-group">
	        <label for="user">用户名：</label>
	        <input type="text" name="user" class="form-control" id="user" placeholder="请输入用户名"/>
	      </div>
	      
	      <div class="form-group">
	        <label for="password">密码：</label>
	        <input type="password" name="password" class="form-control" id="password" placeholder="请输入密码"/>
	      </div>
	      
	      <div class="form-inline">
	        <label for="vcode">验证码：</label>
	        <input type="text" name="verifycode" class="form-control" id="verifycode" placeholder="请输入验证码" style="width: 120px;"/>
	        <a href="javascript:refreshCode()"><img id="img" src="${pageContext.request.contextPath}/checkCodeServlet" title="看不清点击刷新" id="vcode"/></a>
	      </div>
	      <hr/>
	      <div class="form-group" style="text-align: center;">
	        <input class="btn btn btn-primary" type="submit" value="登录">
	       </div>
	  	</form>
		
		<!-- 出错显示的信息框 -->
	  	<div class="alert alert-warning alert-dismissible" role="alert">
		  <button type="button" class="close" data-dismiss="alert" >
		  	<span>&times;</span></button>
		   <strong>登录失败!</strong>
			<div><%=request.getAttribute("cc_error") == null ? "" : request.getAttribute("cc_error")%></div>
			<div><%=request.getAttribute("login_error") == null ? "" : request.getAttribute("login_error") %></div>
		</div>
  	</div>
  </body>
</html>

druid.properties jdbc配置文件

#driverClassName=com.mysql.jdbc.Driver
driverClassName=com.mysql.cj.jdbc.Driver
#url=jdbc:mysql:///day17
url=jdbc:mysql:///db?serverTimezone=UTC
username=root
password=123456
initialSize=5
maxActive=10
maxWait=3000

JDBCUtils 工具类

/**
 * JDBC工具类 使用Durid连接池
 */
public class JDBCUtils {

    private static DataSource ds ;

    static {

        try {
            //1.加载配置文件
            Properties pro = new Properties();
            //使用ClassLoader加载配置文件，获取字节输入流
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);
            //2.初始化连接池对象
            ds = DruidDataSourceFactory.createDataSource(pro);

        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接池对象
     */
    public static DataSource getDataSource(){
        return ds;
    }


    /**
     * 获取连接Connection对象
     */
    public static Connection getConnection() throws SQLException {
        return  ds.getConnection();
    }
}

User类

public class User {
    private int id;
    private String name;
    private String gender;
    private int age;
    private String address;
    private String qq;
    private String email;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getQq() {
        return qq;
    }

    public void setQq(String qq) {
        this.qq = qq;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                ", qq='" + qq + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

UserDao 接口

/**
 * 用户操作的DAO
 */
public interface UserDao {
    public List<User> findAll();
    public User userAdd(User u);
    public String userDelete(String name);
    public Map<String, Object> userFind(String name);
    public boolean userUpdate(User user);
}

UserDaoImpl 实现类

public class UserDaoImpl implements UserDao {

    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    @Override
    public List<User> findAll() {
        //使用JDBC操作数据库...
        //1.定义sql
        String sql = "select * from user";
        List<User> users = template.query(sql, new BeanPropertyRowMapper<User>(User.class));

        return users;
    }
    @Override
    public Map<String, Object> userFind(String name) {
        String sql="select name,gender,age,address,qq,email from user where name = ?";
        Map<String, Object> map = template.queryForMap(sql, name);
        return map;
    }

    @Override
    public User userAdd(User adduser) {
        String sql = "insert into user (name,gender,age,address,qq,email) values(?,?,?,?,?,?)";
        template.update(sql, adduser.getName(),adduser.getGender(),adduser.getAge(),
                adduser.getAddress(),adduser.getQq(),adduser.getEmail());
        return null;
    }

    @Override
    public String userDelete(String name) {
        String sql="delete from user where name = ?";
        template.update(sql,name);
        return null;
    }
    @Override
    public boolean userUpdate(User user) {
        String sql = "update user set gender = ?,age=?,address=?,qq=?,email=? where name = ?";
        template.update(sql,user.getGender(),user.getAge(),user.getAddress(),user.getQq(),user.getEmail(),user.getName());
        return true;
    }

}

UserService 业务接口

/**
 * 用户管理的业务接口
 */
public interface UserService {

    /**
     * 查询所有用户信息
     * @return
     */
    public List<User> findAll();
    public User userAdd(User u);
    public String userDelete(String name);
    public Map<String, Object> userFind(String name);
    public boolean userUpdate(User user);

}

UserServiceImpl 实现类

public class UserServiceImpl implements UserService {
    private UserDao dao = new UserDaoImpl();

    @Override
    public List<User> findAll() {
        //调用Dao完成查询
        return dao.findAll();
    }

    @Override
    public User userAdd(User u) {
        return dao.userAdd(u);
    }

    @Override
    public String userDelete(String name) {
        return dao.userDelete(name);
    }

    @Override
    public Map<String, Object> userFind(String name) {
        return dao.userFind(name);
    }

    @Override
    public boolean userUpdate(User user) {
        return dao.userUpdate(user);
    }
}

UserListServlet 查询所有

@WebServlet("/userListServlet")
public class UserListServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.调用UserService完成查询
        UserService service = new UserServiceImpl();
        List<User> users = service.findAll();
        //2.将list存入request域
        request.setAttribute("users",users);

        //3.转发到list.jsp

        request.getRequestDispatcher("/list.jsp").forward(request,response);

        HttpSession session = request.getSession();
        Cookie c = new Cookie("JSESSIONID", session.getId());
        c.setMaxAge(60*30);
        response.addCookie(c);
        session.setAttribute("users",users);
    }

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

UserAddServlet 添加联系人

@WebServlet("/userListServlet")
public class UserListServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.调用UserService完成查询
        UserService service = new UserServiceImpl();
        List<User> users = service.findAll();
        //2.将list存入request域
        request.setAttribute("users",users);

        //3.转发到list.jsp

        request.getRequestDispatcher("/list.jsp").forward(request,response);

        HttpSession session = request.getSession();
        Cookie c = new Cookie("JSESSIONID", session.getId());
        c.setMaxAge(60*30);
        response.addCookie(c);
        session.setAttribute("users",users);
    }

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

UserDeleteServlet

@WebServlet(name = "userAddServlet", value = "/userAddServlet")
class UserAddServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

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

        request.setCharacterEncoding("utf-8");
        Map<String, String[]> map = request.getParameterMap();
        User u = new User();
        try {
            BeanUtils.populate(u,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        UserServiceImpl service = new UserServiceImpl();
        service.userAdd(u);

    }
}

UserFindServlet 查询单个联系人

@WebServlet(name = "userFindServlet", value = "/userFindServlet")
public class UserFindServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        String name = request.getParameter("name");
        //1.调用UserService完成查询
        HttpSession session = request.getSession();
        List<User> users =(List<User>) session.getAttribute("users");
        if (users != null){
            for (User u:users){
                if(name.equals(u.getName())){
                    request.setAttribute("user",u);
                    request.getRequestDispatcher("/update.jsp").forward(request,response);
                    return ;
                }
            }
        }else{
            UserServiceImpl service = new UserServiceImpl();

            Map<String, Object> map = service.userFind(name);
            User user = new User();
            try {
                BeanUtils.populate(user,map);
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            }
            request.setAttribute("user",user);
            request.getRequestDispatcher("/index.jsp").forward(request,response);
        }
    }
}

UserUpdateServlet 修改联系人信息

@WebServlet(name = "userUpdateServlet", value = "/userUpdateServlet")
public class UserUpdateServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        Map<String, String[]> map = request.getParameterMap();
        User u = new User();
        try {
            BeanUtils.populate(u,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        UserServiceImpl service = new UserServiceImpl();
        service.userUpdate(u);
        request.getRequestDispatcher("/index.jsp").forward(request,response);
    }
}

LoginServlet 登录登录未连数据库，只有验证码刷新

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.设置request编码
        request.setCharacterEncoding("utf-8");
        //2.获取参数
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String checkCode = request.getParameter("checkCode");
        //3.先获取生成的验证码
        HttpSession session = request.getSession();
        String checkCode_session = (String) session.getAttribute("checkCode_session");
        //删除session中存储的验证码
        session.removeAttribute("checkCode_session");
        //3.先判断验证码是否正确
        if(checkCode_session!= null && checkCode_session.equalsIgnoreCase(checkCode)){
            //忽略大小写比较
            //验证码正确
            //判断用户名和密码是否一致
            if("zhangsan".equals(username) && "123".equals(password)){//需要调用UserDao查询数据库
                //登录成功
                //存储信息，用户信息
                session.setAttribute("user",username);
                //重定向到success.jsp
                response.sendRedirect(request.getContextPath()+"/success.jsp");
            }else{
                //登录失败
                //存储提示信息到request
                request.setAttribute("login_error","用户名或密码错误");
                //转发到登录页面
                request.getRequestDispatcher("/login.jsp").forward(request,response);
            }


        }else{
            //验证码不一致
            //存储提示信息到request
            request.setAttribute("cc_error","验证码错误");
            //转发到登录页面
            request.getRequestDispatcher("/login.jsp").forward(request,response);

        }

    }

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

CheckCodeServlet 验证码

@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


        int width = 100;
        int height = 50;

        //1.创建一对象，在内存中图片(验证码图片对象)
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);


        //2.美化图片
        //2.1 填充背景色
        Graphics g = image.getGraphics();//画笔对象
        g.setColor(Color.PINK);//设置画笔颜色
        g.fillRect(0,0,width,height);

        //2.2画边框
        g.setColor(Color.BLUE);
        g.drawRect(0,0,width - 1,height - 1);

        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
        //生成随机角标
        Random ran = new Random();
        StringBuilder sb = new StringBuilder();
        for (int i = 1; i <= 4; i++) {
            int index = ran.nextInt(str.length());
            //获取字符
            char ch = str.charAt(index);//随机字符
            sb.append(ch);

            //2.3写验证码
            g.drawString(ch+"",width/5*i,height/2);
        }
        String checkCode_session = sb.toString();
        //将验证码存入session
        request.getSession().setAttribute("checkCode_session",checkCode_session);

        //2.4画干扰线
        g.setColor(Color.GREEN);

        //随机生成坐标点

        for (int i = 0; i < 10; i++) {
            int x1 = ran.nextInt(width);
            int x2 = ran.nextInt(width);

            int y1 = ran.nextInt(height);
            int y2 = ran.nextInt(height);
            g.drawLine(x1,y1,x2,y2);
        }


        //3.将图片输出到页面展示
        ImageIO.write(image,"jpg",response.getOutputStream());


    }

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