ssm framework implements user login interceptors and filters

The main article is to achieve user authentication login process with interceptor / filter can intercept when the user is not logged, the system can not be accessed page

A: Interceptor

Here is how the custom interceptor project directory implementation:

1: Create a new interceptor interceptor package, create a LoginInterceptor interceptor class

2: this class inherits HandlerInterceptor interfaces, and three methods to achieve this interface HandlerInterceptor

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class LoginInterceptor implements HandlerInterceptor {
 
    @Override
    public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
            throws Exception {
        // 执行完毕，返回前拦截        
    }
 
    @Override
    public void The postHandle (the HttpServletRequest the arg0, the HttpServletResponse arg1, arg2 Object, ModelAndView arg3)
             throws Exception {
         // in the process, performed to intercept         
    } 
 
    @Override 
    public  Boolean The preHandle (the HttpServletRequest Request, Response the HttpServletResponse, Object arg2) throws Exception {
         // intercepting interception point before performing the operation (successful interception) returns true if the intercept point is not executed
         // returns false interception is not performed 
        the HttpSession the session = request.getSession (); 
        String url = request.getRequestURI (); // for login the uri, this is not to intercept    
         //IF (! session.getAttribute ( "_ CURRENT_USER") = null || url.indexOf ( "home.action") = -!. 1 || url.indexOf ( "login.action") = -!. 1) { 
        IF (the session ! .getAttribute ( "_ CURRENT_USER") = null ) {
             // successful login does not block 
            return  to true ; 
        } the else {
             // after intercepting enter the login page 
            response.sendRedirect (request.getContextPath () + "/ home.action" );
             return  to false ; 
        } 
    } 
}

 

3: interceptor is to be configured, this class, arranged in spring-mvc.xml configuration file as follows:

    < Mvc: interceptors > 
        < mvc: Interceptor > 
            <-! Intercept all controllers mvc -> 
            < mvc: Mapping path = "/ **" /> 
<-!              Mvc: Mapping the exclude-intercept is another, it can be a page in your later testing is not intercepted, so do not go 
                get request uri address does not intercept the (preferred) method inside LoginInterceptor of preHandler -> 
            < MVC: Mapping the exclude- path = "/ Home .action "  /> 
            < MVC:-Mapping the exclude path =" / login.action "  /> 
            < the bean class =" cn.itcast.util.LoginInterceptor " > </ the bean >            
        </mvc:interceptor>
    </mvc:interceptors>

 

The landing interceptor class LoginInterceptor, configured to inside

This interceptor has two knowledge points:

①：

< MVC: Mapping path = "/ **" /> is already blocked all requests, including login, if the later does not want to block a page, in the interception of the configuration inside the 
 < MVC: Mapping the exclude- path = "/ the Login. Action "  />

②: the configuration file can not intercept a page request to obtain the path to intercept interception inside the class, and then make a judgment

// String uri = request.getRequestURI (); // get logged uri, this is not to intercept 
        //if(session.getAttribute("LOGIN_USER")!=null || uri.indexOf ( "/ login.action ! ") = - 1)

II: Filters

Filter on two steps: Create a new filter class, then the configuration web.xml

LoginFilter build a class, class inheritance Filter

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.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginFilter implements Filter {
 
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        // TODO Auto-generated method stub
        HttpServletRequest request = (HttpServletRequest)arg0;
        HttpServletResponse response = (HttpServletResponse)arg1;
        HttpSession session = request.getSession();
        
/*        if(session.getAttribute("_CURRENT_USER") != null){
            arg2.doFilter(arg0, arg1);
            return;
        }
        if(request.getRequestURI().indexOf("home.action") != -1 || request.getRequestURI().indexOf("login.action") != -1){
            arg2.doFilter(arg0, arg1);
            return;
        }
        // 没有登录
        response.sendRedirect(request.getContextPath()+"/home.action");*/

        if(session.getAttribute("_CURRENT_USER")==null && request.getRequestURI().indexOf("/home.action") == -1
                    && request.getRequestURI().indexOf("/login.action") == -1 // -1表示不存在该url
                ){
            // 没有登录
            response.sendRedirect(request.getContextPath()+"/home.action");
        }else{
            // 已经登录，继续请求下一级资源（继续访问）
            arg2.doFilter(arg0, arg1);
        }
    }
 
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub
    }
     
    public void destroy() {
        // TODO Auto-generated method stub
    }
}

 

2：配置 web.xml ,在字符过滤器下面接着配置一个过滤器

    <!-- 5.使用filter实现登录控制 -->
    <filter>
        <filter-name>LoginFilter</filter-name>
        <filter-class>cn.itcast.util.LoginFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>LoginFilter</filter-name>
        <!-- 所有的管理页面需要登录后才能访问 -->
        <url-pattern>/*</url-pattern>
    </filter-mapping>

 

将过滤器类  LoginFilter  配置到 过滤器配置文件中，即可完成

过滤器也实现了

 

内容大部分来自https://blog.csdn.net/chenxihua1/article/details/80779234 感谢大佬分享！