JavaWeb16.4【Cookie&Session：JSP入门】
2021/7/2 22:23:15
本文主要是介绍JavaWeb16.4【Cookie&Session：JSP入门】，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！
index.jsp
1 <%--
2 Created by IntelliJ IDEA.
3 User: yubaby
4 Date: 2021/7/2
5 Time: 14:35
6 To change this template use File | Settings | File Templates.
7 --%>
8 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
9 <html>
10 <head>
11 <title>$Title$</title>
12 </head>
13 <body>
14
15 <%
16 System.out.println("hello jsp, i'm back"); //输出到IDEA控制台
17 %>
18 <h1>hi,jsp</h1> <%--输出到浏览器页面--%>
19
20
21 <% response.getWriter().write("response....."); %>
22
23 <% //在Servlet的service方法中
24 System.out.println("hello jsp, i'm back");
25 int i = 5;
26
27 String contextPath = request.getContextPath(); //request、response、out为内置对象，不用声明，可以直接用，因为servlet类中定义了
28 out.print(contextPath); // /day16
29 %>
30 <%! //在Servlet类的成员位置
31 int i = 3;
32 %>
33 <%= //输出到页面上
34 i //5，因为就近原则，service方法中定义的局部变量i的作用域较小
35 %>
36 <%= "hello" %>
37
38 <% response.getWriter().write("response*****"); %>
39 </body>
40 </html>
index_jsp.java
1 /*
2 * Generated by the Jasper component of Apache Tomcat
3 * Version: Apache Tomcat/8.5.31
4 * Generated at: 2021-07-02 12:33:12 UTC
5 * Note: The last modified time of this file was set to
6 * the last modified time of the source file after
7 * generation to assist with modification tracking.
8 */
9 package org.apache.jsp;
10
11 import javax.servlet.*;
12 import javax.servlet.http.*;
13 import javax.servlet.jsp.*;
14
15 public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase
16 implements org.apache.jasper.runtime.JspSourceDependent,
17 org.apache.jasper.runtime.JspSourceImports {
18
19 //在Servlet类的成员位置
20 int i = 3;
21
22 private static final javax.servlet.jsp.JspFactory _jspxFactory =
23 javax.servlet.jsp.JspFactory.getDefaultFactory();
24
25 private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;
26
27 private static final java.util.Set<java.lang.String> _jspx_imports_packages;
28
29 private static final java.util.Set<java.lang.String> _jspx_imports_classes;
30
31 static {
32 _jspx_imports_packages = new java.util.HashSet<>();
33 _jspx_imports_packages.add("javax.servlet");
34 _jspx_imports_packages.add("javax.servlet.http");
35 _jspx_imports_packages.add("javax.servlet.jsp");
36 _jspx_imports_classes = null;
37 }
38
39 private volatile javax.el.ExpressionFactory _el_expressionfactory;
40 private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;
41
42 public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
43 return _jspx_dependants;
44 }
45
46 public java.util.Set<java.lang.String> getPackageImports() {
47 return _jspx_imports_packages;
48 }
49
50 public java.util.Set<java.lang.String> getClassImports() {
51 return _jspx_imports_classes;
52 }
53
54 public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
55 if (_el_expressionfactory == null) {
56 synchronized (this) {
57 if (_el_expressionfactory == null) {
58 _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
59 }
60 }
61 }
62 return _el_expressionfactory;
63 }
64
65 public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
66 if (_jsp_instancemanager == null) {
67 synchronized (this) {
68 if (_jsp_instancemanager == null) {
69 _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
70 }
71 }
72 }
73 return _jsp_instancemanager;
74 }
75
76 public void _jspInit() {
77 }
78
79 public void _jspDestroy() {
80 }
81
82 public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
83 throws java.io.IOException, javax.servlet.ServletException {
84
85 final java.lang.String _jspx_method = request.getMethod();
86 if (!"GET".equals(_jspx_method) && !"POST".equals(_jspx_method) && !"HEAD".equals(_jspx_method) && !javax.servlet.DispatcherType.ERROR.equals(request.getDispatcherType())) {
87 response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "JSPs only permit GET POST or HEAD");
88 return;
89 }
90
91 final javax.servlet.jsp.PageContext pageContext;
92 javax.servlet.http.HttpSession session = null;
93 final javax.servlet.ServletContext application;
94 final javax.servlet.ServletConfig config;
95 javax.servlet.jsp.JspWriter out = null;
96 final java.lang.Object page = this;
97 javax.servlet.jsp.JspWriter _jspx_out = null;
98 javax.servlet.jsp.PageContext _jspx_page_context = null;
99
100
101 try {
102 response.setContentType("text/html;charset=UTF-8");
103 pageContext = _jspxFactory.getPageContext(this, request, response,
104 null, true, 8192, true);
105 _jspx_page_context = pageContext;
106 application = pageContext.getServletContext();
107 config = pageContext.getServletConfig();
108 session = pageContext.getSession();
109 out = pageContext.getOut();
110 _jspx_out = out;
111
112 out.write("\n");
113 out.write("\n");
114 out.write("<html>\n");
115 out.write(" <head>\n");
116 out.write(" <title>$Title$</title>\n");
117 out.write(" </head>\n");
118 out.write(" <body>\n");
119 out.write("\n");
120 out.write(" ");
121
122 System.out.println("hello jsp, i'm back"); //输出到IDEA控制台
123
124 out.write("\n");
125 out.write(" <h1>hi,jsp</h1> ");
126 out.write("\n");
127 out.write("\n");
128 out.write("\n");
129 out.write(" ");
130 response.getWriter().write("response.....");
131 out.write("\n");
132 out.write("\n");
133 out.write(" ");
134 //在Servlet的service方法中
135 System.out.println("hello jsp, i'm back");
136 int i = 5;
137
138 String contextPath = request.getContextPath(); //request、response、out为内置对象，不用声明，可以直接用，因为servlet类中定义了
139 out.print(contextPath); // /day16
140
141 out.write("\n");
142 out.write(" ");
143 out.write("\n");
144 out.write(" ");
145 out.print( //输出到页面上
146 i //5，因为就近原则，service方法中定义的局部变量i的作用域较小
147 );
148 out.write("\n");
149 out.write(" ");
150 out.print( "hello" );
151 out.write("\n");
152 out.write("\n");
153 out.write(" ");
154 response.getWriter().write("response*****");
155 out.write("\n");
156 out.write(" </body>\n");
157 out.write("</html>\n");
158 } catch (java.lang.Throwable t) {
159 if (!(t instanceof javax.servlet.jsp.SkipPageException)){
160 out = _jspx_out;
161 if (out != null && out.getBufferSize() != 0)
162 try {
163 if (response.isCommitted()) {
164 out.flush();
165 } else {
166 out.clearBuffer();
167 }
168 } catch (java.io.IOException e) {}
169 if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
170 else throw new ServletException(t);
171 }
172 } finally {
173 _jspxFactory.releasePageContext(_jspx_page_context);
174 }
175 }
176 }
apache-tomcat-8.5.31-src tomcat部分源码
HttpJspBase.java
1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.jasper.runtime;
19
20 import java.io.IOException;
21
22 import javax.servlet.ServletConfig;
23 import javax.servlet.ServletException;
24 import javax.servlet.http.HttpServlet;
25 import javax.servlet.http.HttpServletRequest;
26 import javax.servlet.http.HttpServletResponse;
27 import javax.servlet.jsp.HttpJspPage;
28
29 import org.apache.jasper.compiler.Localizer;
30
31 /**
32 * This is the super class of all JSP-generated servlets.
33 *
34 * @author Anil K. Vijendran
35 */
36 public abstract class HttpJspBase extends HttpServlet implements HttpJspPage {
37
38 private static final long serialVersionUID = 1L;
39
40 protected HttpJspBase() {
41 }
42
43 @Override
44 public final void init(ServletConfig config)
45 throws ServletException
46 {
47 super.init(config);
48 jspInit();
49 _jspInit();
50 }
51
52 @Override
53 public String getServletInfo() {
54 return Localizer.getMessage("jsp.engine.info");
55 }
56
57 @Override
58 public final void destroy() {
59 jspDestroy();
60 _jspDestroy();
61 }
62
63 /**
64 * Entry point into service.
65 */
66 @Override
67 public final void service(HttpServletRequest request, HttpServletResponse response)
68 throws ServletException, IOException
69 {
70 _jspService(request, response);
71 }
72
73 @Override
74 public void jspInit() {
75 }
76
77 public void _jspInit() {
78 }
79
80 @Override
81 public void jspDestroy() {
82 }
83
84 protected void _jspDestroy() {
85 }
86
87 @Override
88 public abstract void _jspService(HttpServletRequest request,
89 HttpServletResponse response)
90 throws ServletException, IOException;
91 }
1 <%@ page import="java.net.URLDecoder" %>
2 <%@ page import="java.util.Date" %>
3 <%@ page import="java.text.SimpleDateFormat" %>
4 <%@ page import="java.net.URLEncoder" %><%--
5 Created by IntelliJ IDEA.
6 User: yubaby
7 Date: 2021/7/2
8 Time: 20:49
9 To change this template use File | Settings | File Templates.
10 --%>
11 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
12 <html>
13 <head>
14 <title>Title</title>
15 </head>
16 <body>
17
18 <%
19 //设置响应的消息体的数据格式以及编码，防止中文乱码
20 // response.setContentType("text/html;charset=utf-8");
21
22 //1 获取所有cookie
23 Cookie[] cookies = request.getCookies();
24 boolean flag = false; //false表示没有名为lastTime的cookie
25
26 //2 遍历cookie数组
27 if (cookies!=null && cookies.length>0){
28 for (Cookie cookie : cookies) {
29 //3 获取cookie的名称
30 String name = cookie.getName();
31 //4 判断cookie名称是否为"lastTime"
32 if ("lastTime".equals(name)){
33 //有该cookie，说明不是第一次访问
34 flag = true;
35
36 //(1) 响应数据
37 String value = cookie.getValue();
38 //-----------------------------------------
39 //URL解码
40 System.out.println("解码前：" + value);
41 value = URLDecoder.decode(value, "utf-8");
42 System.out.println("解码后：" + value);
43 //-----------------------------------------
44 // response.getWriter().write("<h1>欢迎回来，您上次访问时间为:" + value + "</h1>");
45 // out.write("<h1>欢迎回来，您上次访问时间为:" + value + "</h1>"); //采用out输出不会影响页面布局
46 %> <%--jsp代码可以截断--%>
47
48 <h1>欢迎回来，您上次访问时间为:<%=value%></h1>
49
50 <%
51 //(2) 写回Cookie
52 Date date = new Date();
53 SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
54 String str_date = sdf.format(date);
55 //-----------------------------------------
56 //URL编码（在tomcat8之后，cookie支持中文数据，但如空格等特殊字符还是不支持）
57 System.out.println("编码前：" + str_date);
58 str_date = URLEncoder.encode(str_date, "utf-8");
59 System.out.println("编码后：" + str_date);
60 //-----------------------------------------
61 cookie.setValue(str_date);
62 cookie.setMaxAge(60 * 60 * 24 * 30); //设置缓存一个月
63 response.addCookie(cookie);
64
65 break;
66 }
67 }
68 }
69
70 if (cookies==null || cookies.length==0 || flag==false){
71 //无该cookie，说明是第一次访问
72 flag = true;
73
74 //(1) 响应数据
75 // response.getWriter().write("<h1>您好，欢迎您首次访问</h1>");
76 // out.write("<h1>您好，欢迎您首次访问</h1>");
77 %>
78
79 <h1>您好，欢迎您首次访问</h1>
80
81 <%
82 //(2) 写回Cookie
83 Date date = new Date();
84 SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
85 String str_date = sdf.format(date);
86 //-----------------------------------------
87 //URL编码
88 System.out.println("编码前：" + str_date);
89 str_date = URLEncoder.encode(str_date, "utf-8");
90 System.out.println("编码后：" + str_date);
91 //-----------------------------------------
92 Cookie c = new Cookie("lastTime", str_date);
93 c.setMaxAge(60 * 60 * 24 * 30); //设置缓存一个月
94 response.addCookie(c);
95 }
96 %>
97
98 </body>
99 </html>
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