cookie、session和java過濾器聯合完成上岸法式。本站提示廣大學習愛好者：（cookie、session和java過濾器聯合完成上岸法式）文章只能為提供參考，不一定能成為您想要的結果。以下是cookie、session和java過濾器聯合完成上岸法式正文
cookie、session和過濾器平日都是用在web運用中，cookie和session用來保留必定的數據，過濾器Filter則是在閱讀器收回要求以後，爾後台履行特定的要求之前產生必定的感化。之所以把這三個放一路，是由於有許多時刻都邑是把他們聯合在一路應用，例若有些上岸法式。
cookie是閱讀器的機制，session是辦事器的機制，然則現實上cookie也是由辦事器生成的，以後前往給閱讀器的，其實不是閱讀器自己生成。當閱讀器發送某個要求時，假如具有有用的cookie則會把這個cookie帶在一路。
之一切會有cookie的應用，是由於http協定本來是無狀況協定，也就是說經由過程http協定自己，辦事器不克不及斷定閱讀器能否之前拜訪過。
Filter和servlet的寫法類似，編寫相干代碼的時刻須要完成Filter接口偏重寫相干的辦法，平日更改較多的是doFilter辦法。Filter代碼寫好今後假如須要產生功效，須要像設置裝備擺設servlet一樣在web.xml中 停止必定的設置裝備擺設。
以下是一個簡略的聯合cookie、session、Servlet和Filter的上岸示例代碼：
界說一個用戶實體類，充任數據庫數據，這裡應用單例形式，包管只存在一個實例對象：
package models;
/**
* 用戶信息實體類
*
* @author tuzongxun123
*
*/
public class UserModel {
private String userName;
private String password;
// 單例形式，包管只要一個用戶對象實例
public static UserModel getInstance() {
UserModel user = new UserModel("zhangsan", "123456");
return user;
}
private UserModel(String userName, String pasword) {
this.userName = userName;
this.password = pasword;
}
public String getUserName() {
return userName;
}
public String getPassword() {
return password;
}
}
用戶上岸輸出信息index.jsp界面，在form表單的action中應用jsp的特征取得項目途徑：
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>cookieAndFilterTest</title>
</head>
<body>
<form action="<%=request.getContextPath() %>/loginServlet" method="post">
userName：<input type="text" name="userName" /></br>
password：<input type="password" name="password" /></br>
<input type="submit" value="login"/>
</form>
</body>
</html>
對應的後台servlet：
package servletTest;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import models.UserModel;
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String userName = req.getParameter("userName");
String password = req.getParameter("password");
// 模仿數據庫數據
UserModel user = UserModel.getInstance();
String dbUserName = user.getUserName();
String dbPassword = user.getPassword();
if (dbUserName.equals(userName) && dbPassword.equals(password)) {
// 用戶名和暗碼都婚配，證實上岸勝利，設置session和cookie
HttpSession session = req.getSession();
session.setAttribute("userName", userName);
session.setAttribute("password", password);
Cookie cookie = new Cookie("userName", userName);
Cookie cookie2 = new Cookie("password", password);
// 設置cookie的存儲時長
cookie.setMaxAge(60);
cookie2.setMaxAge(60);
// 把cookie發送給閱讀器
resp.addCookie(cookie);
resp.addCookie(cookie2);
// 轉發要求到用戶列表
req.getRequestDispatcher("/userList").forward(req, resp);
} else {
// 轉發要求到上岸頁面
req.getRequestDispatcher("index.jsp").forward(req, resp);
}
;
}
}
上邊上岸後跳轉的要求：
package servletTest;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import models.UserModel;
public class UserListServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
UserModel user = UserModel.getInstance();
//在閱讀器中打印出用戶列表書數據
resp.getWriter().write(
"userName:" + user.getUserName() + "," + "password:"
+ user.getPassword());
}
}
項目web.xml設置裝備擺設：
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> <!-- 拜訪時的項目稱號 --> <display-name>cookieAndFilterTest</display-name> <!-- servlet設置裝備擺設 --> <servlet> <servlet-name>login</servlet-name> <servlet-class>servletTest.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>login</servlet-name> <url-pattern>/loginServlet</url-pattern> </servlet-mapping> <servlet> <servlet-name>userList</servlet-name> <servlet-class>servletTest.UserListServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>userList</servlet-name> <url-pattern>/userList</url-pattern> </servlet-mapping> <!-- 過濾器設置，閱讀其發送要求後起首會走這裡 --> <filter> <filter-name>loginFilter</filter-name> <filter-class>filterTest.FilterTest</filter-class> </filter> <filter-mapping> <filter-name>loginFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!-- 輸出項目名拜訪的默許頁面 --> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
java過濾器代碼：
package filterTest;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import models.UserModel;
public class FilterTest implements Filter {
@Override
public void destroy() {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// 上岸要求、初始要求直接放行
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse resp = (HttpServletResponse) response;
String uri = req.getRequestURI();
if ("/cookieAndFilterTest/loginServlet".equals(uri)
|| "/cookieAndFilterTest/".equals(uri)) {
// 放行
chain.doFilter(request, response);
return;
}
// 不是上岸要求的話，斷定能否有cookie
Cookie[] cookies = req.getCookies();
if (cookies != null && cookies.length > 0) {
String userName = null;
String password = null;
// 斷定cookie中的用戶名和暗碼能否和數據庫中的分歧，假如分歧則放行，不然轉發要求到上岸頁面
for (Cookie cookie : cookies) {
if ("userName".equals(cookie.getName())) {
userName = cookie.getValue();
}
if ("password".equals(cookie.getName())) {
password = cookie.getValue();
}
}
UserModel user = UserModel.getInstance();
if (user.getUserName().equals(userName)
&& user.getPassword().equals(password)) {
chain.doFilter(request, response);
return;
} else {
// 重定向到上岸界面
req.getRequestDispatcher("/index.jsp").forward(req, resp);
return;
}
} else {
req.getRequestDispatcher("/index.jsp").forward(req, resp);
return;
}
}
@Override
public void init(FilterConfig arg0) throws ServletException {
}
}
以上就是本文的全體內容，願望對年夜家進修java法式設計有所贊助。
