今天在做session对象存入redis（set方法）时，碰到一个空指针异常，代码如下：
public class CheckAccount extends HttpServlet { public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{ HttpSession session=request.getSession(); AccountBean account=new AccountBean(); String username=request.getParameter("username"); String password=request.getParameter("password"); account.setPassword(password); account.setUsername(username); if((username!=null)&&(username.trim().equals("jsp"))){ if((password!=null)&&(password.trim().equals("1"))){ session.setAttribute("account", account); SessionService.getInstance().SaveSession(session); //System.out.println(session.getId()); String logon_suc="session.jsp"; response.sendRedirect(logon_suc); return ; } } String logon_fail="fail.jsp"; response.sendRedirect(logon_fail); return; } public void doPost (HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{ doGet(request,response); } }
属性如下所示:
public class AccountBean { private static final long serialVersionUID = 1390366007623566261L; 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; } }
输出jsp代码为：
<body>
<%=request.getSession().getId()%><br/>
<% AccountBean account=(AccountBean)request.getSession().getAttribute("account");%>
user name:<%=account.getUsername() %><br/>
password:<%=account.getPassword() %><br/>
</body>
出错原因：AccountBean 作为session的属性，因session继承Serializable，被持久化保存到redis中，所以作完属性的AccountBean也必须序列化才能被存入redis中。