过滤器、监听器常用
过滤器、监听器常用
监听器：GUI编程中经常使用
public class GUIDemo1 {
public static void main(String[] args) {
JFrame jFrame = new JFrame("监听");
Panel panel = new Panel(null);
jFrame.setBounds(300,300,500,500);
jFrame.setBackground(new Color(53, 220, 64));
jFrame.setLayout(null);
panel.setBounds(30,30,300,300);
panel.setBackground(new Color(19, 0, 121));
jFrame.add(panel);
jFrame.setVisible(true);
jFrame.addWindowListener(new WindowAdapter() {
@Override
public void windowClosing(WindowEvent e) {
super.windowClosing(e);
}
});
}
}
用户登入后才能进入主页，用户注销后就进入登入页面。
- 用户登入之后向session中放入用户的数据
- 进入主页的时候要判断用户是否登入：用Filter实现。
Login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<h1>登入页面</h1>
<head>
<title>Title</title>
</head>
<body>
<form action="login" method="post">
<input type="text" name="username">
<br>
<input type="submit" value="登入">
</form>
</body>
</html>
success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>登入成功，执行下面操作</h1>
<br>
<a href="../logout">注销</a>
</body>
</html>
error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>登入失败</h1>
<h2>你没有访问的权限</h2>
<a href="Login.jsp">重新登入</a>
</body>
</html>
LoginServlet
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String username = req.getParameter("username");
if(username.equals("admin")){
req.getSession().setAttribute(USER_SESSION,req.getSession().getId());
resp.sendRedirect("sys/success.jsp");
}else{
resp.sendRedirect("error.jsp");
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
LogoutServlet
@WebServlet("/logout")
public class LogoutServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Object user_session = req.getSession().getAttribute("USER_SESSION");
if(user_session!=null){
req.getSession().removeAttribute("USER_SESSION");
resp.sendRedirect("Login.jsp");
}else{
resp.sendRedirect("Login.jsp");
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
SysFilter
@WebFilter("/sys/*")
public class SysFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) servletRequest;
HttpServletResponse resp = (HttpServletResponse) servletResponse;
if(req.getSession().getAttribute(USER_SESSION)==null){
resp.sendRedirect("../error.jsp");
}
filterChain.doFilter(req,resp);
}
@Override
public void destroy() {
}
}
