JavaWeb session——模擬實現使用者登入（教材學習筆記）
阿新 • • 發佈：2018-12-03
首先我們要了解使用者登入的整個流程，
1、從瀏覽器訪問網站首頁IndexServlet
2、判斷用後是否登入
3、若以登入則顯示使用者資訊
4、若未登入，進圖登入介面login.html;
4.1、處理使用者登入資訊（LoginServlet）
4.2、判斷使用者名稱和密碼是否正確
4.3、若正確則顯示使用者資訊
4.4、若不正確則提示使用者名稱或密碼錯誤
5、若使用者退出，則進入LogoutServlet介面
下面我們通過上面的流程來建立程式碼，
一、建立封裝使用者資訊類
建立一個名為web-chapter05的web專案，並在其中建立cn.itcast.chapter05.session.example02的包，並在包中建立一個User類
程式碼如下：
package cn.itcast.chapter05.session.example02; 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; } }
二、建立IndexServlet類
在cn.itcast.chapter05.session.example02的包中建立IndexServlet類，該類是顯示網站的首頁
package cn.itcast.chapter05.session.example02; import java.io.*; import javax.servlet.ServletException; import javax.servlet.http.*; public class IndexServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //解決亂碼問題 response.setContentType("text/html;charset=utf-8"); //建立或者獲取儲存使用者資訊的session物件 HttpSession session = request.getSession(); User user = (User) session.getAttribute("user"); if(user==null) { response.getWriter().print("您還沒有登入，請<a href='/web-chapter05/login.html'>登入</a>"); }else { response.getWriter().print("您已登入，歡迎你，"+ user.getUsername()+"！"); response.getWriter().print("<a href='/web-chapter05/LogoutServlet'>退出</a>"); //建立cookie存放session的標識號 Cookie cookie = new Cookie("JSESSIONID", session.getId()); cookie.setMaxAge(60*30); cookie.setPath("/web-chapter05"); response.addCookie(cookie); } } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
三、建立LoginServlet類
在cn.itcast.chapter05.session.example02的包中建立LoginServlet類，該類是顯示網站的登入頁
package cn.itcast.chapter05.session.example02;
import java.io.*;
import javax.servlet.ServletException;
import javax.servlet.http.*;
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//解決亂碼問題
response.setContentType("text/html;charset=utf-8");
String username = request.getParameter("username");
String password = request.getParameter("password");
PrintWriter pw = response.getWriter();
if(("itcast").equals(username)&&("123456").equals(password)) {
User user = new User();
user.setUsername(username);
user.setPassword(password);
request.getSession().setAttribute("user", user);
response.sendRedirect("/web-chapter05/IndexServlet");
}else {
pw.write("使用者名稱或者密碼錯誤，登入失敗");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
四、建立LogoutServlet類
在cn.itcast.chapter05.session.example02的包中建立LogoutServlet類，該類是顯示網站的退出及登出頁面
package cn.itcast.chapter05.session.example02;
import java.io.*;
import javax.servlet.ServletException;
import javax.servlet.http.*;
public class LogoutServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//將session物件中的user物件移除,之後重定向到首頁
request.getSession().removeAttribute("user");
response.sendRedirect("/web-chapter05/IndexServlet");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
五、建立登入頁面
在web-chapter05專案的WebContent目錄下建立一個名為login.html的頁面
<!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>Insert title here</title>
</head>
<body>
<form name="reg" action="/web-chapter05/LoginServlet" method="post">
使用者名稱: <input name="username" type="text" /><br/>
密 碼：<input name="password" type="password" /><br/>
<input type="submit" value="提交" id="bt" />
</form>
</body>
</html>六、在web.xml中配置相關的三個servlet
<servlet>
<description></description>
<display-name>IndexServlet</display-name>
<servlet-name>IndexServlet</servlet-name>
<servlet-class>cn.itcast.chapter05.session.example02.IndexServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>IndexServlet</servlet-name>
<url-pattern>/IndexServlet</url-pattern>
</servlet-mapping>
<servlet>
<description></description>
<display-name>LoginServlet</display-name>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>cn.itcast.chapter05.session.example02.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
<servlet>
<description></description>
<display-name>LogoutServlet</display-name>
<servlet-name>LogoutServlet</servlet-name>
<servlet-class>cn.itcast.chapter05.session.example02.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LogoutServlet</servlet-name>
<url-pattern>/LogoutServlet</url-pattern>
</servlet-mapping>七、啟動tomcat，在瀏覽器測試
在瀏覽器網址欄中輸入http://localhost:8080/web-chapter05/login.html，進入下面的介面
然後輸入之前在程式中設定好的賬號itcast，和密碼123456，進入下面的介面
點選退出連結就會進入下面的介面
如果點選登入的話就會接著進入登入的介面
至此，一個簡單的模擬實現使用者登入就完成了