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 ... %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
分类:
1. page: 配置JSP页面的
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" %>
:只能注释html代码片段<%-- --%>
:可以注释所有
M:Model,模型。JavaBean
V:View,视图。JSP
C:Controller,控制器。Servlet
优缺点:
优点:
缺点:
jsp默认支持el表达式的。如果要忽略el表达式
\${表达式}
:忽略当前这个el表达式${empty list}
:判断字符串、集合、数组对象是否为null或者长度为0${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>Titletitle>
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>
${域名称.键名}
:从指定域中获取指定键的值
${requestScope.name}
${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}
${sessionScope.name}
body>
html>
对象:${域名称.键名.属性名}
List集合:${域名称.键名[索引]}
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>
${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>
${pageContext.request.contextPath}
<%
%>
body>
html>
是由Apache组织提供的开源的免费的jsp标签 <标签>
<%@ taglib %>
1. if:相当于java代码的if语句
<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>if标签title>
head>
<body>
<c:if test="true">
<h1>我是真...h1>
c:if>
<br>
<%
//判断request域中的一个list集合是否为空,如果不为null则显示遍历集合
List list = new ArrayList();
list.add("aaaa");
request.setAttribute("list",list);
request.setAttribute("number",4);
%>
<c:if test="${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}">
${number}为偶数
c:if>
body>
html>
2. choose:相当于java代码的switch语句
使用choose标签声明 相当于switch声明
使用when标签做判断 相当于case
使用otherwise标签做其他情况的声明 相当于default
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>choose标签title>
head>
<body>
<%
request.setAttribute("number",51);
%>
<c:choose>
<c:when test="${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} ${str}<br>
c:forEach>
body>
html>
4. 练习:
需求:在request域中有一个存有User对象的List集合。需要使用jstl+el将list集合数据展示到jsp页面的表格table中
<%@ page import="cn.itcast.domain.User" %>
<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ page import="java.util.Date" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>testtitle>
head>
<body>
<%
List list = new ArrayList();
list.add(new User("张三",23,new Date()));
list.add(new User("李四",24,new Date()));
list.add(new User("王五",25,new Date()));
request.setAttribute("list",list);
%>
<table border="1" width="500" align="center">
<tr>
<th>编号th>
<th>姓名th>
<th>年龄th>
<th>生日th>
tr>
<%--数据行--%>
<c:forEach items="${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>
技术选型:Servlet+JSP+MySQL+JDBCTempleat+Duird+BeanUtilS+tomcat
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)
);
环境搭建
编码
UserListServlet代码
package cn.itcast.web.servlet;
import cn.itcast.domain.User;
import cn.itcast.service.UserService;
import cn.itcast.service.impl.UserServiceImpl;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;
@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);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
list.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="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>用户信息管理系统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>
<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>QQth>
<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.html">修改a> <a class="btn btn-default btn-sm" href="">删除a>td>
tr>
c:forEach>
<tr>
<td colspan="8" align="center"><a class="btn btn-primary" href="add.html">添加联系人a>td>
tr>
table>
div>
body>
html>
UserService代码
package cn.itcast.service;
import cn.itcast.domain.User;
import java.util.List;
/**
* 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();
}
UserServiceImpl代码
package cn.itcast.service.impl;
import cn.itcast.dao.UserDao;
import cn.itcast.dao.impl.UserDaoImpl;
import cn.itcast.domain.User;
import cn.itcast.service.UserService;
import java.util.List;
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();
}
}
UserDao
package cn.itcast.dao;
import cn.itcast.domain.User;
import java.util.List;
/**
* 用户操作的DAO
*/
public interface UserDao {
public List<User> findAll();
}
UserDaoImpl
package cn.itcast.dao.impl;
import cn.itcast.dao.UserDao;
import cn.itcast.domain.User;
import cn.itcast.util.JDBCUtils;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import java.util.List;
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;
}
}