十二月 20, 2015 19:59:17
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处理cookie
? ? ? 1.Http协议的无连接性要求一种保存C/S间状态的机制
? ? ? 2.Coolie:保存到客户端的一个文本文件，与特定客户无关
? ? ? 3.Cookie以“名--值”对的形式保存数据
? ? ? 4.创建Cookie:new Cookie(name，value)
? ? ? 5.可以使用Cookie 的serXXX方法来设定一些相应的值
? ? ? ? ?5.1 setName(String name)/getName()
? ? ? ? ?5.2 setValue(String value)/getValue()
? ? ? ? ?5.3 setMaxAge(int age)/getMaxAge()
? ? ? ? ?5.4 利用HttpServletResponse的addCookie(Cookie)方法将它设置到客户端
? ? ? ? ?5.5 利用HttpServletRequest的getCookies()方法来读取客户端的所有的cookie。
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一、cookie原理:
基本原理:
1.服务器可以向客户端写的内容，
2.只能是文本文档
3.客户端可以阻止不让写
4.只能拿自己的webapp写的东西(一个浏览器的标记)
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? ? ?是服务器在本地写的内容，可以进行阻止写入cookie，
在internet选项-->隐私-->高（阻止所有cookie）
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cookie在本地的地址:
? C盘.....C:\Documents and Settings\Administrator\Cookies
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Documents and Settings\Administrator\Cookies
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server向client端的cookies；
1.如果设置周期时，写在本地；
2.未设置或者为-1时，是写在client端的内存里；关掉本窗口，就没了。
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5.cookie分为两种
? ? 属于窗口/子窗口
? ? 属于文本
6.一个servlet/jsp设置的cookies能够被同一个路径下面或者子路径下面的servlet/jsp读到(路径=url)
（路径！=真实文件路径）
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二、cookie代码案例
SetCookies.java
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 设置Cookie到客户端
* @author jukey
*
*/
public class SetCookies extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 向客户端写入Cookie，共6个
for(int i = 0; i < 3; i++) {
// 3个没设置时间的Cookie，属于本窗口及其子窗口
Cookie cookie = new Cookie("Session-Cookie-" + i, "Cookie-Value-S" + i);
response.addCookie(cookie);
// 以下3个Cookie设置了时间（3600秒，1小时，属于文本，别的窗口也可以访问到这些Cookie
cookie = new Cookie("Persistent-Cookie-" + i, "Cookie-Value-P" + i);
cookie.setMaxAge(3600);
response.addCookie(cookie);
}
response.setContentType("text/html;charset=gb2312");
PrintWriter out = response.getWriter();
String title = "Setting Cookies";
out.println("<html><head><title>设置Cookie</title></head>"
+ "<body>" + title + "<br>"
+ "There are six cookies associates with this page.<br>"
+ "to see them,visit the <a href=\"ShowCookies\">\n"
+ "<code>ShowCookies</code> servlet</a>"
+ "</body></html>");
}
}
?ShowCookies
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 读取客户端的Cookies
*/
public class ShowCookies extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=gb2312");
PrintWriter pw = response.getWriter();
String title = "Active Cookies";
pw.println("init");
pw.println("<html><head><title>读取客户端</title></head>"
+ title
+ "\n" + "<table border=1 align=center>\n"
+ "<TH>Cookie Name<TH>Cookie Value" + "<br>");
// 读取客户端的所Cookie
Cookie[] cookies = request.getCookies();
if(cookies != null) {
Cookie cookie;
for(int i = 0; i < cookies.length; i++) {
cookie = cookies[i];
pw.println("<tr>\n" + "<td>" + cookie.getName() +"</td>\n"
+ "<td>" + cookie.getValue() +"</td></tr>\n");
}
}
pw.println("</table>\n<body><html>");
}
}
?web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>HelloServlet</servlet-name>
<servlet-class>HelloServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>ServletLifeCycle</servlet-name>
<servlet-class>ServletLifeCycle</servlet-class>
</servlet>
<servlet>
<servlet-name>ThreeParams</servlet-name>
<servlet-class>ThreeParams</servlet-class>
</servlet>
<servlet>
<servlet-name>ShowParameters</servlet-name>
<servlet-class>ShowParameters</servlet-class>
</servlet>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>SetCookies</servlet-name>
<servlet-class>SetCookies</servlet-class>
</servlet>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>ShowCookies</servlet-name>
<servlet-class>ShowCookies</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloServlet</servlet-name>
<url-pattern>/httpServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>ServletLifeCycle</servlet-name>
<url-pattern>/ServletLifeCycle</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>ThreeParams</servlet-name>
<url-pattern>/ThreeParams</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>ShowParameters</servlet-name>
<url-pattern>/servlet/ShowParameters</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>SetCookies</servlet-name>
<url-pattern>/servlet/SetCookies</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>ShowCookies</servlet-name>
<url-pattern>/servlet/ShowCookies</url-pattern>
</servlet-mapping>
</web-app>
?结果:
本地cookies存在的
Persistent-Cookie-0
Cookie-Value-P0
localhost/TestServlet01/servlet/
1536
1530043264
30489391
4193558928
30489382
*
Persistent-Cookie-1
Cookie-Value-P1
localhost/TestServlet01/servlet/
1536
1530043264
30489391
4193558928
30489382
*
Persistent-Cookie-2
Cookie-Value-P2
localhost/TestServlet01/servlet/
1536
1530043264
30489391
4193558928
30489382
*
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三、会话跟踪 Session
? 3.1 在某段时间一连串客户端与服务器端的交易
? 3.2 在Jsp/Servlet中，如果浏览器不支持Cookie，可以通过URL重写来实现，就试讲一些额外数据追加到表示会话的每个URL末尾，
? ? ? ? 服务器在该标识符与其存储的有关的该会话的数据之间建立关联。
? ? ? ? ?如: ?hello.jsp?jsessionid=1234
? 3.3 可以通过程序来终止一个会话。如果客户端在一定时间内没有操作，服务器会自动终止会话。
? 3.3 通过HttpSession来读写Session
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规则:
? ?1.如果浏览器支持Cookie，创建Session的还好会把SessionID保存在Cookie里
? ? 2.如果不支持Cookie，必须自己变成使用URL重写的方式实现Session
? ? ? ? ?2.1 response.encodeURL()
? ? ? ? ? ? ? ?转码
? ? ? ? ? ? ? ?URL后面加入SessionId
? ? ? ? ?2.2Session不像Cookie拥有路径访问的问题
? ? ? ? ? ? ?同一个application下的servet/jsp可以共享同一个session，前提是同一客户端窗口。
?
session是和窗口关联起来的，窗口关了这个sessionid就没了
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?
?
HttpServletRequest中的Session管理方法
1.getRequestSessionId()：
? ? ?返回随客户端请求到来的会话ID。可能与当前的会话ID相同，也可能不同。
?2.getSession(boolean isNew): 如果会话已存在一个HttpSession，如果不存在并且isNew()为true，则会创建一个HttpSession。
?3.isRequestedSessionIdFromCookie()：当前的session ID如果是从cookie获得，为true。
?4.isRequestedSessionIdValid()： 如果客户端的会话ID代表的是有效会话，则返回true。否则(比如，会话国企或根本不存在)，返回false。
?5.HttpSession的常用方法:
? ? ?5.1getAtrributeNames()/getAttribute()
? ? ?5.2getCreateTime()
? ? ?5.3getId()
? ? ?5.4 getMaxInactiveInterval()
? ? ?5.5invalidate()
? ? ?5.6 isNew()
? ? ?5.7 setAttribuye()
? ? ?5.8 setMaxInactivateInterval()?
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refresh后jsessionid=45F4C3391CB26DAE6B28C104B6571A12
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?out.println("<a href=" + response.encodeURL("SessionInfoServlet") + ">refresh</a>");
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http://localhost:8080/TestServlet01/servlet/SessionInfoServlet;jsessionid=45F4C3391CB26DAE6B28C104B6571A12
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代码案例
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* 演示Servlet API中的session管理机制（常用方法）
* @author jukey
*
*/
public class SessionInfoServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// Returns the current session associated with this request, or if the request does not have a session, creates one.
HttpSession mySession = request.getSession(true);
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Session Info Servlet";
out.println("<html>");
out.println("<head>");
out.println("<title>Session Info Servlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<h3>Session Infomation</h3>");
// Returns true if the client does not yet know about the session or if the client chooses not to join the session.
out.println("New Session:" + mySession.isNew() + "<br>");
// Returns a string containing the unique identifier assigned to this session.
out.println("Session Id:" + mySession.getId() + "<br>");
// Returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT.
out.println("Session Create Time:" + new Date(mySession.getCreationTime()) + "<br>");
out.println("Session Last Access Time:" + new Date(mySession.getLastAccessedTime()) + "<br>");
out.println("<h3>Request Infomation</h3>");
// Returns the session ID specified by the client.
out.println("Session Id From Request:" + request.getRequestedSessionId() + "<br>");
// Checks whether the requested session ID came in as a cookie.
out.println("Session Id Via Cookie:" + request.isRequestedSessionIdFromCookie() + "<br>");
// Checks whether the requested session ID came in as part of the request URL.
out.println("Session Id Via URL:" + request.isRequestedSessionIdFromURL() + "<br>");
// Checks whether the requested session ID is still valid.
out.println("Valid Session Id:" + request.isRequestedSessionIdValid() + "<br>");
out.println("<a href=" + response.encodeURL("SessionInfoServlet") + ">refresh</a>");
out.println("</body></html>");
out.close();
}
}
?ShowSession
?
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* Session追踪
* 如果浏览器支持Cookie，创建Session的时候会把SessionId保存在Cookie中
* 否则必须自己编程使用URL重写的方式实现Session：response.encodeURL()
* @author jukey
*
*/
public class ShowSession extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=gb2312");
PrintWriter out = response.getWriter();
String str = "Session Tracking Example";
String heading;
// 如果会话已经存在，则返回一个HttpSession；否则创建一个新的
HttpSession session = request.getSession(true);
// 从当前session中读取属性accessCount的值
Integer accessCount = (Integer)session.getAttribute("accessCount");
if(accessCount == null) {
accessCount = new Integer(0);
heading = "Welcome newUser";
} else {
heading = "Welcome Back";
accessCount = new Integer(accessCount.intValue() + 1);
}
// 向当前session中插入键（key，属性）值（value）对
// Binds an object to this session, using the name specified.
session.setAttribute("accessCount", accessCount);
out.println("<html><head><title>Session追踪</title></head>"
+ "<body>" + heading + "<br>"
+ "<h2>Information on Your Session</h2><br>"
+ "\n" + "<table border=1 align=center>\n"
+ "<TH>Info Type<TH>Value" + "<br>"
+ "<tr>\n" + "<td>ID</td>\n"
+ "<td>" + session.getId() +"</td></tr>\n"
+ "<tr>\n" + "<td>CreatTime</td>\n"
+ "<td>" + new Date(session.getCreationTime()) +"</td></tr>\n"
+ "<tr>\n" + "<td>LastAccessTime</td>\n"
+ "<td>" + new Date(session.getLastAccessedTime()) +"</td></tr>\n"
+ "<tr>\n" + "<td>Number of Access</td>\n"
+ "<td>" + accessCount +"</td></tr>\n"
+ "</body></html>");
}
}
?四、Application
4.1 用于保存整个WebApplication的生命周期内都可以访问的数据
4.2 在API中表现为ServletContext
4.3通过HttpServlet的getServletContext方法可以拿到
4.4通过ServletContext的get/setAttribute方法取得/设置相关属性
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?
http://localhost:8080/TestServlet01/servlet/TestServletContext
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?
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Application测试
* 用于保存整个web应用的生命周期内都可以访问的数据
* 可供多个不同窗口访问，可作为某一页面被总共访问次数的计数器（比如网站首页的访问量）
* @author jukey
*
*/
public class TestServletContext extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=gb2312");
PrintWriter out = response.getWriter();
// Returns a reference to the ServletContext in which this servlet is running.
ServletContext application = this.getServletContext();
// 从当前application中读取属性accessCount的值
Integer accessCount = (Integer)application.getAttribute("accessCount");
if(accessCount == null) {
accessCount = new Integer(0);
} else {
accessCount = new Integer(accessCount.intValue() + 1);
}
// 向当前application中插入键（key，属性值（value对
application.setAttribute("accessCount", accessCount);
out.println("<html><head><title>ServletContext测试</title></head><br>"
+ "<body><td>" + accessCount +"</td>\n"
+ "</body></html>");
}
}
?web.xml
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>TestServletContext</servlet-name>
<servlet-class>TestServletContext</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>TestServletContext</servlet-name>
<url-pattern>/servlet/TestServletContext</url-pattern>
</servlet-mapping>
?
Servlet类本身位于包中的情况?
?
HelloWorldServlet2
http://localhost:8080/TestServlet01/servlet/HelloWorldServlet2
package com.bjsxt.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet类本身位于包中的情况
* classes中要class文件及其各级目录一起放置
* web中如下设置：<servlet-class>com.bjsxt.servlet.HelloWorldServlet2</servlet-class>
* @author jukey
*
*/
public class HelloWorldServlet2 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=gb2312");
PrintWriter out = response.getWriter();
out.println("Hello World!");
}
}
?web.xml
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>HelloWorldServlet2</servlet-name>
<servlet-class>com.bjsxt.servlet.HelloWorldServlet2</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorldServlet2</servlet-name>
<url-pattern>/servlet/HelloWorldServlet2</url-pattern>
</servlet-mapping>
?星期日, 十二月 20, 2015 22:28:38
day_05cookie+session+application
原文：http://yuzhouxiner.iteye.com/blog/2265330