package com.ischoolbar.programmer.interceptor; import java.util.HashMap; import java.util.Map; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import net.sf.json.JSONObject; import org.springframework.web.servlet.HandlerInterceptor; import org.springframework.web.servlet.ModelAndView; import com.ischoolbar.programmer.entity.User; /** * 登录过滤拦截器 * @author llq * */ public class LoginInterceptor implements HandlerInterceptor{ @Override public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3) throws Exception { // TODO Auto-generated method stub } @Override public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3) throws Exception { // TODO Auto-generated method stub } @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object arg2) throws Exception { // TODO Auto-generated method stub String url = request.getRequestURI(); //System.out.println("进入拦截器，url = " + url); Object user = request.getSession().getAttribute("user"); if(user == null){ //表示未登录或者登录状态失效 System.out.println("未登录或登录失效，url = " + url); if("XMLHttpRequest".equals(request.getHeader("X-Requested-With"))){ //ajax请求 Map<String, String> ret = new HashMap<String, String>(); ret.put("type", "error"); ret.put("msg", "登录状态已失效，请重新去登录!"); response.getWriter().write(JSONObject.fromObject(ret).toString()); return false; } response.sendRedirect(request.getContextPath() + "/system/login"); return false; } return true; } }给代码加上注释

//导入相关的包
package com.ischoolbar.programmer.interceptor;

import java.util.HashMap;
import java.util.Map;

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

import net.sf.json.JSONObject;

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

import com.ischoolbar.programmer.entity.User;

/**
* 登录过滤拦截器
*
* @author llq
*
*/
public class LoginInterceptor implements HandlerInterceptor {

//在请求处理完成后调用的方法
@Override
public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
throws Exception {
// TODO Auto-generated method stub

}

//在请求处理之后但是视图渲染之前调用的方法
@Override
public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
throws Exception {
// TODO Auto-generated method stub

}

//在请求处理之前调用的方法
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object arg2) throws Exception {
// TODO Auto-generated method stub
String url = request.getRequestURI(); //获取请求的url
//System.out.println("进入拦截器，url = " + url);
Object user = request.getSession().getAttribute("user"); //获取session中的user对象
if (user == null) { //如果session中的user对象为空，表示未登录或者登录状态失效
System.out.println("未登录或登录失效，url = " + url);
if ("XMLHttpRequest".equals(request.getHeader("X-Requested-With"))) { //如果是ajax请求
Map<String, String> ret = new HashMap<String, String>();
ret.put("type", "error");
ret.put("msg", "登录状态已失效，请重新去登录!");
response.getWriter().write(JSONObject.fromObject(ret).toString()); //返回JSON格式的错误信息
return false;
}
response.sendRedirect(request.getContextPath() + "/system/login"); //跳转到登录页面
return false;
}
return true;
}
}