JavaWeb 使用Filter實現使用者自動登入（教材學習筆記）
阿新 • • 發佈：2018-12-03
1.編寫User類
package cn.itcast.chapter08.entity; public class User { private String username; private String password; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
2.實現登入頁面
login.jsp程式碼如下
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8" import="java.util.*"%> <html> <head></head> <center><h3>使用者登入</h3></center> <body style="text-align: center;"> <form action="${pageContext.request.contextPath }/LoginServlet" method="post"> <table border="1" width="600px" cellpadding="0" cellspacing="0" align="center" > <tr> <td height="30" align="center">使用者名稱：</td> <td> <input type="text" name="username" />${errerMsg }</td> </tr> <tr> <td height="30" align="center">密 碼：</td> <td> <input type="password" name="password" /></td> </tr> <tr> <td height="35" align="center">自動登入時間</td> <td><input type="radio" name="autologin" value="${60*60*24*31 }" />一個月 <input type="radio" name="autologin" value="${60*60*24*31*3 }" />三個月 <input type="radio" name="autologin" value="${60*60*24*31*6 }" />半年 <input type="radio" name="autologin" value="${60*60*24*31*12 }" />一年 </td> </tr> <tr> <td height="30" colspan="2" align="center"> <input type="submit" value="登入" /> <input type="reset" value="重置" /> </td> </tr> </table> </form> </body> <html>
3.實現主頁面
inde.jsp程式碼如下：
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8" import="java.util.*" %> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <html> <head> <title>顯示登入的使用者資訊</title> </head> <body> <br /> <center> <h3>歡迎光臨</h3> </center> <br /> <br /> <c:choose> <c:when test="${sessionScope.user==null }"> <a href="${pageContext.request.contextPath }/login.jsp">使用者登入</a> </c:when> <c:otherwise> 歡迎你，${sessionScope.user.username }! <a href="${pageContext.request.contextPath }/LogoutServlet">登出</a> </c:otherwise> </c:choose> <hr /> </body> </html>
4、在cn.itcast.chapter08.filter包中建立LoginServlet類
程式碼如下：
package cn.itcast.chapter08.filter;
import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.*;
import cn.itcast.chapter08.entity.User;
public class LoginServlet extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
// 獲得使用者名稱和密碼
String username = request.getParameter("username");
String password = request.getParameter("password");
// 檢查使用者名稱和密碼
if ("itcast".equals(username) && "123456".equals(password)) {
// 登入成功
// 將使用者狀態 user 物件存入 session域
User user = new User();
user.setUsername(username);
user.setPassword(password);
request.getSession().setAttribute("user", user);
// 傳送自動登入的cookie
String autoLogin = request.getParameter("autologin");
if (autoLogin != null) {
// 注意 cookie 中的密碼要加密
Cookie cookie = new Cookie("autologin", username + "-"
+ password);
cookie.setMaxAge(Integer.parseInt(autoLogin));
cookie.setPath(request.getContextPath());
response.addCookie(cookie);
}
// 跳轉至首頁
response.sendRedirect(request.getContextPath()+"/index.jsp");
} else {
request.setAttribute("errerMsg", "使用者名稱或密碼錯");
request.getRequestDispatcher("/login.jsp")
.forward(request,response);
}
}
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
5、編寫LogoutServlet類，
程式碼如下：
package cn.itcast.chapter08.filter;
import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.*;
public class LogoutServlet extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
// 使用者登出
request.getSession().removeAttribute("user");
// 從客戶端刪除自動登入的cookie
Cookie cookie = new Cookie("autologin", "msg");
cookie.setPath(request.getContextPath());
cookie.setMaxAge(0);
response.addCookie(cookie);
response.sendRedirect(request.getContextPath()+"/index.jsp");
}
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
6、建立過濾器
AutoLoginFilter類程式碼如下：
package cn.itcast.chapter08.filter;
import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.*;
import cn.itcast.chapter08.entity.User;
public class AutoLoginFilter implements Filter {
public void init(FilterConfig filterConfig) throws ServletException {
}
public void doFilter(ServletRequest req, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
// 獲得一個名為 autologin 的cookie
Cookie[] cookies = request.getCookies();
String autologin = null;
for (int i = 0; cookies != null && i < cookies.length; i++) {
if ("autologin".equals(cookies[i].getName())) {
// 找到了指定的cookie
autologin = cookies[i].getValue();
break;
}
}
if (autologin != null) {
// 做自動登入
String[] parts = autologin.split("-");
String username = parts[0];
String password = parts[1];
// 檢查使用者名稱和密碼
if ("itcast".equals(username)&& ("123456").equals(password)) {
// 登入成功,將使用者狀態 user 物件存入 session域
User user = new User();
user.setUsername(username);
user.setPassword(password);
request.getSession().setAttribute("user", user);
}
}
// 放行
chain.doFilter(request, response);
}
public void destroy() {
}
}
7、在web.xml中配置相關的幾個servlet以及filter檔案
程式碼如下：
<filter>
<filter-name>AutoLoginFilter</filter-name>
<filter-class>cn.itcast.chapter08.filter.AutoLoginFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>AutoLoginFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>cn.itcast.chapter08.filter.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>LogoutServlet</servlet-name>
<servlet-class>cn.itcast.chapter08.filter.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LogoutServlet</servlet-name>
<url-pattern>/LogoutServlet</url-pattern>
</servlet-mapping>8、執行tomcat，檢視結果
在瀏覽器網址欄輸入http://localhost:8080/web-chapter08/index.jsp 結果如下：
點選使用者登入：
點選登入之後，新開啟一個瀏覽器重新輸入http://localhost:8080/web-chapter08/index.jsp，結果如下：
可以看到這此沒有登入就直接進入了主頁面