1 <%@ page import="java.util.List" %>
2 <%@ page import="java.util.ArrayList" %><%--
3 Created by IntelliJ IDEA.
4 User: yubaby
5 Date: 2021/7/3
6 Time: 19:33
7 To change this template use File | Settings | File Templates.
8 --%>
9 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
10 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
11
12 <html>
13 <head>
14 <title>JSTL常用标签：if</title>
15 </head>
16 <body>
17
18 <%--
19 c:if标签
20 1. 属性：
21 * test 必须属性，接受boolean表达式
22 * 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
23 * 一般情况下，test属性值会结合el表达式一起使用
24 2. 注意：
25 * 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
26 --%>
27 <c:if test="true">
28 <h1>真的</h1>
29 </c:if>
30 <c:if test="flase">
31 <h1>假的</h1>
32 </c:if>
33
34
35 <%
36 //判断request域中的一个list集合是否为空，若不为null则显示遍历该集合
37
38 List list = new ArrayList();
39 list.add("aaa");
40 list.add("bbb");
41 request.setAttribute("list", list);
42
43 request.setAttribute("num", 3);
44 %>
45
46 <c:if test="${not empty list}">
47 ${requestScope.list}
48 </c:if>
49 <br>
50
51 <c:if test="${num % 2 != 0}">
52 ${num}是奇数
53 </c:if>
54 <c:if test="${num % 2 == 0}">
55 ${num}是偶数
56 </c:if>
57
58 </body>
59 </html>
1 <%--
2 Created by IntelliJ IDEA.
3 User: yubaby
4 Date: 2021/7/3
5 Time: 20:12
6 To change this template use File | Settings | File Templates.
7 --%>
8 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
9 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
10
11 <html>
12 <head>
13 <title>JSTL常用标签：choose</title>
14 </head>
15 <body>
16
17 <%--
18 完成数字编号对应星期几案例
19 1.域中存储一数字
20 2.使用choose标签取出数字 相当于switch声明
21 3.使用when标签做数字判断 相当于case
22 4.otherwise标签做其他情况的声明 相当于default
23 --%>
24
25 <%
26 request.setAttribute("num", 3);
27 %>
28 <c:choose>
29 <c:when test="${num == 1}">星期一</c:when>
30 <c:when test="${num == 2}">星期二</c:when>
31 <c:when test="${num == 3}">星期三</c:when>
32 <c:when test="${num == 4}">星期四</c:when>
33 <c:when test="${num == 5}">星期五</c:when>
34 <c:when test="${num == 6}">星期六</c:when>
35 <c:when test="${num == 7}">星期天</c:when>
36 <c:otherwise>输入有误</c:otherwise>
37 </c:choose>
38
39 </body>
40 </html>
1 <%@ page import="java.util.List" %>
2 <%@ page import="java.util.ArrayList" %><%--
3 Created by IntelliJ IDEA.
4 User: yubaby
5 Date: 2021/7/3
6 Time: 20:19
7 To change this template use File | Settings | File Templates.
8 --%>
9 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
10 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
11 <html>
12 <head>
13 <title>JSTL常用标签：foreach</title>
14 </head>
15 <body>
16
17 <%--
18
19 foreach:相当于java代码的for语句
20 1. 完成重复的操作
21 for(int i = 0; i < 10; i++){}
22 * 属性：
23 begin：开始值
24 end：结束值
25 var：临时变量
26 step：步长
27 varStatus:循环状态对象
28 index:容器中元素的索引，从0开始
29 count:循环次数，从1开始
30 2. 遍历容器
31 List<User> list;
32 for(User user: list){}
33 * 属性：
34 items:容器对象
35 var:容器中元素的临时变量
36 varStatus:循环状态对象
37 index:容器中元素的索引，从0开始
38 count:循环次数，从1开始
39 --%>
40
41 <c:forEach begin="1" end="10" var="i" step="1"> <%--属性顺序严格--%>
42 ${i}<br>
43 </c:forEach>
44 <hr>
45
46 <c:forEach begin="1" end="10" var="i" step="2">
47 ${i}<br>
48 </c:forEach>
49 <hr>
50
51 <c:forEach begin="1" end="10" var="i" step="2" varStatus="s">
52 ${i} ${s.index} ${s.count}<br>
53 </c:forEach>
54 <hr>
55
56
57 <%
58 List list = new ArrayList();
59 list.add("aaa");
60 list.add("bbb");
61 list.add("ccc");
62 request.setAttribute("list", list);
63 %>
64 <c:forEach items="${list}" var="str" varStatus="s">
65 ${str} ${s.index} ${s.count}<br>
66 </c:forEach>
67
68 </body>
69 </html>
1 package com.haifei.domain;
2
3 import java.text.SimpleDateFormat;
4 import java.util.Date;
5
6 public class User {
7 private String name;
8 private int age;
9 private Date birthday;
10
11 /**
12 * 逻辑视图
13 * (并没有专门对应的成员属性birthdayStr，而仅仅是处理一下birthday方便页面展示)
14 * @return
15 */
16 public String getBirthdayStr(){
17 //格式化日期对象
18 if (birthday != null){
19 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
20 /*String birthdayStr = sdf.format(birthday);
21 return birthdayStr;*/
22 return sdf.format(birthday);
23 }else{
24 return "";
25 }
26 }
27
28 public User() {
29 }
30
31 public User(String name, int age, Date birthday) {
32 this.name = name;
33 this.age = age;
34 this.birthday = birthday;
35 }
36
37 public String getName() {
38 return name;
39 }
40
41 public int getAge() {
42 return age;
43 }
44
45 public Date getBirthday() {
46 return birthday;
47 }
48
49 public void setName(String name) {
50 this.name = name;
51 }
52
53 public void setAge(int age) {
54 this.age = age;
55 }
56
57 public void setBirthday(Date birthday) {
58 this.birthday = birthday;
59 }
60 }
1 <%@ page import="java.util.List" %>
2 <%@ page import="java.util.ArrayList" %>
3 <%@ page import="com.haifei.domain.User" %>
4 <%@ page import="java.util.Date" %><%--
5 Created by IntelliJ IDEA.
6 User: yubaby
7 Date: 2021/7/3
8 Time: 20:36
9 To change this template use File | Settings | File Templates.
10 --%>
11 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
12 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
13 <html>
14 <head>
15 <title>el+jstl案例</title>
16 </head>
17 <body>
18 <%
19 List list = new ArrayList();
20 list.add(new User("zhangsan", 23, new Date()));
21 list.add(new User("lisi", 22, new Date()));
22 list.add(new User("wangwu", 24, new Date()));
23 request.setAttribute("list", list);
24 %>
25
26 <table border="1" width="500" align="center">
27 <tr>
28 <th>编号</th>
29 <th>姓名</th>
30 <th>年龄</th>
31 <th>生日</th>
32 </tr>
33 <%--数据行--%>
34 <c:forEach items="${list}" var="user" varStatus="s">
35 <c:if test="${s.count % 2 == 0}">
36 <tr bgcolor="red">
37 <td>${s.count}</td>
38 <td>${user.name}</td>
39 <td>${user.age}</td>
40 <td>${user.birthdayStr}</td>
41 </tr>
42 </c:if>
43 <c:if test="${s.count % 2 != 0}">
44 <tr bgcolor="green">
45 <td>${s.count}</td>
46 <td>${user.name}</td>
47 <td>${user.age}</td>
48 <td>${user.birthdayStr}</td>
49 </tr>
50 </c:if>
51 </c:forEach>
52 </table>
53 </body>
54 </html>