核心标签库：
![]()
1 <%@ page
2 language="java"
3 import="java.util.*"
4 pageEncoding="utf-8"
5 session="true"
6 %>
7
8 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
9 <html>
10 <head>
11 <title>page指令</title>
12 </head>
13
14 <body>
15 <%
16 //String name = null;
17 //name.charAt(1);
18 int i = 100/0;
19
20 HttpSession session1 = request.getSession();
21 //session.getId();
22 %>
23 </body>
24 </html>
25 <%@ page language="java" import="java.util.*" pageEncoding="utf-8" buffer="1kb"%><%
26 for(int i=1;i<=1024;i++){
27 out.write("a");
28 }
29 //查看缓存区大小
30 System.out.println("当前缓存区大小："+out.getBufferSize());
31 //查看缓存区剩余大小
32 System.out.println("缓存区剩余大小："+out.getRemaining());
33 //刷新缓存
34 //out.flush();
35 response.getWriter().write("123");
36 %>
37 </body>
38 </html>
39 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
40
41 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
42 <html>
43 <head>
44 <title>从四个域中获取数据</title>
45 </head>
46
47 <body>
48 page域：<%=pageContext.getAttribute("message",PageContext.PAGE_SCOPE) %><br/>
49 request域： <%=pageContext.getAttribute("message",PageContext.REQUEST_SCOPE) %><br/>
50 session域： <%=pageContext.getAttribute("message",PageContext.SESSION_SCOPE) %><br/>
51 context域：<%=pageContext.getAttribute("message",PageContext.APPLICATION_SCOPE) %><br/>
52 </body>
53 </html>
54 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
55
56 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
57 <html>
58 <head>
59 <title>EL语法</title>
60 </head>
61
62 <body>
63 <%
64 String name = "rose";
65 //放入域中
66 //pageContext.setAttribute("name",name);
67 pageContext.setAttribute("name",name,PageContext.REQUEST_SCOPE);
68 %>
69 <%=name %>
70 <br/>
71 <%--
72 1)从四个域自动搜索
73 --%>
74 EL表达式： ${name }
75 <%--
76 ${name } 等价于
77 <%=pageContext.findAttribute("name")%>
78 --%>
79 <%--
80 2） 从指定的域中获取数据
81 --%>
82 EL表达式： ${pageScope.name }
83 <%--
84 ${pageScope.name } 等价于
85 <%= pageContext.getAttribute("name",PageContext.PAGE_SCOPE)%>
86
87 --%>
88 </body>
89 </html>
90 <%@ page language="java" import="java.util.*,gz.itcast.b_entity.*" pageEncoding="utf-8"%>
91
92 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
93 <html>
94 <head>
95 <title>EL输出不同类型的数据</title>
96 </head>
97
98 <body>
99 <%--
100 1)EL输出对象的属性
101 --%>
102 <%
103 //保存数据
104 Student student = new Student("eric",20);
105 //放入域中
106 pageContext.setAttribute("student",student);
107
108 //List
109 List<Student> list = new ArrayList<Student>();
110 list.add(new Student("rose",18));
111 list.add(new Student("jack",28));
112 list.add(new Student("lucy",38));
113 //放入域中
114 pageContext.setAttribute("list",list);
115
116 //Map
117 Map<String,Student> map = new HashMap<String,Student>();
118 map.put("100",new Student("mark",20));
119 map.put("101",new Student("maxwell",30));
120 map.put("102",new Student("narci",40));
121 //放入域中
122 pageContext.setAttribute("map",map);
123
124 %>
125
126 <%--使用EL获取对象 --%>
127 ${student.name} - ${student.age }
128 <%--
129 ${student.name} 等价于 （点相对于调用getXX（）方法）
130 <%=((Student)pageContext.findAttribute("student")).getName()%>
131 --%>
132
133 <hr/>
134 <%--使用EL获取List对象 --%>
135 ${list[0].name } - ${list[0].age }<br/>
136 ${list[1].name } - ${list[1].age }<br/>
137 ${list[2].name } - ${list[2].age }
138 <%--
139 list[0]等价于 (中括号相对于调用get(参数)方法)
140 ((List)pageContext.findAttribute("list")).get(0)
141 --%>
142 <hr/>
143 <%--使用EL获取Map对象 --%>
144 ${map['100'].name } - ${map['100'].age }<br/>
145 ${map['101'].name } - ${map['101'].age }<br/>
146 ${map['102'].name } - ${map['102'].age }<br/>
147 </body>
148 </html>
149 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
150
151 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
152 <html>
153 <head>
154 <title>EL表达式计算</title>
155 </head>
156
157 <body>
158 <%--
159 1)算术表达式
160 + - * /
161 --%>
162 ${10+5 }<br/>
163 ${10*5 }
164 <hr/>
165 <%--
166 2)比较运算
167 > < >= <= == !=
168 --%>
169 ${10>5 }<br/>
170 ${10<5 }<br/>
171 ${10!=10 }
172 <hr/>
173 <%--
174 3)逻辑运算
175 && || !
176 --%>
177 ${true && false }<br/>
178 ${true || false }<br/>
179 ${!false }<br/>
180 <hr/>
181 <%--
182 4)判空
183 null 或 空字符串: empty
184 --%>
185 <%
186 //String name = "eric";
187 //String name = null;
188 String name = "";
189 pageContext.setAttribute("name",name);
190 %>
191 判断null： ${name==null }<br/>
192 判断空字符： ${name=="" }<br/>
193 判空： ${name==null || name=="" }
194 另一种判空写法： ${empty name }
195
196
197 </body>
198 </html>
199 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
200
201 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
202 <html>
203 <head>
204 <title>动作标签</title>
205 </head>
206
207 <body>
208 <%--转发 --%>
209 <%
210 //request.getRequestDispatcher("/09.action2.jsp?name=eric").forward(request,response);
211 %>
212 <%-- 参数 --%>
213 <%--
214 <jsp:forward page="/09.action2.jsp">
215 <jsp:param value="jacky" name="name"/>
216 <jsp:param value="123456" name="password"/>
217 </jsp:forward>
218 --%>
219
220 <%--包含 --%>
221 <%--
222 <jsp:include page="/common/header.jsp">
223 <jsp:param value="lucy" name="name"/>
224 </jsp:include>
225 --%>
226 <%@include file="common/header.jsp" %>
227 主页的内容
228
229 </body>
230 </html>
231 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
232
233 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
234 <html>
235 <head>
236 <title>动作标签</title>
237 </head>
238
239 <body>
240 <%--转发 --%>
241 <%
242 //request.getRequestDispatcher("/09.action2.jsp?name=eric").forward(request,response);
243 %>
244 <%-- 参数 --%>
245 <%--
246 <jsp:forward page="/09.action2.jsp">
247 <jsp:param value="jacky" name="name"/>
248 <jsp:param value="123456" name="password"/>
249 </jsp:forward>
250 --%>
251
252 <%--包含 --%>
253 <%--
254 <jsp:include page="/common/header.jsp">
255 <jsp:param value="lucy" name="name"/>
256 </jsp:include>
257 --%>
258 <%@include file="common/header.jsp" %>
259 主页的内容
260
261 </body>
262 </html>
View Code