EL表达式
什么是EL表达式
EL的作用域对象
EL表达式的输出
JSTL
JSTL是什么
2.2 下载JSTL标签库
JSTL的标签库种类
引用JSTL核心库
Example1
package com.jesse.jstl;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class JstlServlet
*/
@WebServlet("/jstl")
public class JstlServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public JstlServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setAttribute("score", 78);
request.setAttribute("grade", "B");
request.getRequestDispatcher("/core.jsp").forward(request, response);
}
}
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri = "http://java.sun.com/jsp/jstl/core" prefix = "c" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>${requestScope.score}</h1>
<c:if test="${score >= 60 }">
<h1 style = "color:green">恭喜，你已通过测试</h1>
</c:if>
<c:if test="${score < 60 }">
<h1 style = "color:red">对不起，再接再厉</h1>
</c:if>
<!-- choose when otherwise -->
${grade}
<c:choose>
<c:when test="${grade == 'A'}">
<h2>你很优秀</h2>
</c:when>
<c:when test="${grade == 'B' }">
<h2>不错呦</h2>
</c:when>
<c:when test="${grade == 'C' }">
<h2>水平一般，需要提高</h2>
</c:when>
<c:otherwise>
<h2>一切随缘吧</h2>
</c:otherwise>
</c:choose>
</body>
</html>
Example2
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
request.setAttribute("amt", 1987654.326);
request.setAttribute("now", new java.util.Date());
request.setAttribute("html", "<a href='index.html'>index</a>");
request.setAttribute("nothing", null);
%>
<h2>${now }</h2>
<!-- formateDate pattern
yyyy - 四位年
MM - 两位月
dd - 两位日
HH - 24小时制
hh - 12小时制
mm - 分钟
ss - 秒数
SSS - 毫秒
-->
<h2>
<fmt:formatDate value="${requestScope.now }" pattern="yyyy年MM月dd日HH时mm分ss秒SSS毫秒"/>
</h2>
<h2>${amt }</h2>
<h2>
¥<fmt:formatNumber value = "${amt }" pattern = "0,000.00"></fmt:formatNumber>元
</h2>
<h2>null默认值：<c:out value="${nothing }" default="无"></c:out></h2>
<h2><c:out value="${html }" escapeXml="true"></c:out></h2>
</body>
</html>
案例：员工信息表
package com.jesse.employee;
public class Employee {
private Integer empno;
private String ename;
private String department;
private String job;
private Float salary;
public Employee(Integer empno, String ename, String department, String job, Float salary) {
super();
this.empno = empno;
this.ename = ename;
this.department = department;
this.job = job;
this.salary = salary;
}
public Integer getEmpno() {
return empno;
}
public void setEmpno(Integer empno) {
this.empno = empno;
}
public String getEname() {
return ename;
}
public void setEname(String ename) {
this.ename = ename;
}
public String getDepartment() {
return department;
}
public void setDepartment(String department) {
this.department = department;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public Float getSalary() {
return salary;
}
public void setSalary(Float salary) {
this.salary = salary;
}
}
package com.jesse.employee;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class ListServlet
*/
@WebServlet("/list")
public class ListServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ListServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext context = request.getServletContext();
if(context.getAttribute("employees") == null) {
List<Employee> list = new ArrayList<Employee>();
list.add(new Employee(1100, "孔金星", "Java工程师", "项目经理", 20000f));
list.add(new Employee(1101, "张东方", "光学工程师", "研发经理", 25000f));
context.setAttribute("employees", list);
}
request.getRequestDispatcher("/employee.jsp").forward(request, response);
}
}
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>员工列表</title>
<link href="css/bootstrap.css" type="text/css" rel="stylesheet"></link>
<script type="text/javascript" src="js/jquery-1.11.1.min.js"></script>
<script type="text/javascript" src="js/bootstrap.js"></script>
<style type="text/css">
.pagination {
margin: 0px
}
.pagination > li > a, .pagination > li > span {
margin: 0 5px;
border: 1px solid #dddddd;
}
.glyphicon {
margin-right: 3px;
}
.form-control[readonly] {
cursor: pointer;
background-color: white;
}
#dlgPhoto .modal-body{
text-align: center;
}
.preview{
max-width: 500px;
}
</style>
<script>
$(function () {
$("#btnAdd").click(function () {
$('#dlgForm').modal()
});
})
</script>
</head>
<body>
<div class="container">
<div class="row">
<h1 style="text-align: center">JESSE员工信息表</h1>
<div class="panel panel-default">
<div class="clearfix panel-heading ">
<div class="input-group" style="width: 500px;">
<button class="btn btn-primary" id="btnAdd"><span class="glyphicon glyphicon-zoom-in"></span>新增
</button>
</div>
</div>
<table class="table table-bordered table-hover">
<thead>
<tr>
<th>序号</th>
<th>员工编号</th>
<th>姓名</th>
<th>部门</th>
<th>职务</th>
<th>工资</th>
<th> </th>
</tr>
</thead>
<tbody>
<c:forEach items = "${applicationScope.employees }" var = "emp" varStatus="idx">
<tr>
<td>${idx.index+1 }</td>
<td>${emp.empno }</td>
<td>${emp.ename }</td>
<td>${emp.department }</td>
<td>${emp.job }</td>
<td style="color: red;font-weight: bold">￥<fmt:formatNumber value = "${emp.salary }" pattern="0,000.00"></fmt:formatNumber> </td>
</tr>
</c:forEach>
</tbody>
</table>
</div>
</div>
</div>
<!-- 表单 -->
<div class="modal fade" tabindex="-1" role="dialog" id="dlgForm">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span>
</button>
<h4 class="modal-title">新增员工</h4>
</div>
<div class="modal-body">
<form action="/employee/create" method="post" >
<div class="form-group">
<label for="empno">员工编号</label>
<input type="text" name="empno" class="form-control" id="empno" placeholder="请输入员工编号">
</div>
<div class="form-group">
<label for="ename">员工姓名</label>
<input type="text" name="ename" class="form-control" id="ename" placeholder="请输入员工姓名">
</div>
<div class="form-group">
<label>部门</label>
<select id="dname" name="department" class="form-control">
<option selected="selected">请选择部门</option>
<option value="市场部">市场部</option>
<option value="研发部">研发部</option>
<option value="后勤部">后勤部</option>
</select>
</div>
<div class="form-group">
<label>职务</label>
<input type="text" name="job" class="form-control" id="sal" placeholder="请输入职务">
</div>
<div class="form-group">
<label for="sal">工资</label>
<input type="text" name="salary" class="form-control" id="sal" placeholder="请输入工资">
</div>
<div class="form-group" style="text-align: center;">
<button type="submit" class="btn btn-primary">保存</button>
</div>
</form>
</div>
</div><!-- /.modal-content -->
</div><!-- /.modal-dialog -->
</div><!-- /.modal -->
</body>
</html>
package com.jesse.employee;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class CreateServlet
*/
@WebServlet("/create")
public class CreateServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public CreateServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
String empno = request.getParameter("empno");
String ename = request.getParameter("ename");
String department = request.getParameter("department");
String job = request.getParameter("job");
String salary = request.getParameter("salary");
Employee emp = new Employee(Integer.parseInt(empno), ename, department, job, Float.parseFloat(salary));
ServletContext context = request.getServletContext();
List employees = (List)context.getAttribute("employees");
employees.add(emp);
context.setAttribute("employees", employees);
request.getRequestDispatcher("/employee.jsp").forward(request, response);
}
}
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