目录
1.前言
使用拦截器,主要是为了拦截用户的请求并进行相应的处理,比如通过拦截器进行用户登录验证,用户权限验证等;SpringMVC中的拦截器拦截请求是通过实现HandleInterceptor接口来完成;
2.HandleInterceptor接口
2.1 HandleInterceptor接口定义了三个方法:
2.1.1 boolean public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) :该方法在请求处理之前被调用,若在一个应用中或者一个请求中存在多个Interceptor,每个Interceptor的调用会根据他的声明顺序依次执行;方法返回Boolean类型,当返回false时,表示请求结束,后续的Interceptor和Controller将不会再执行,当返回true时,会据需调用下一个Interceptor的preHandle方法,执行到最后一个Interceptor,就会调用当前请求的控制器方法。
2.1.2 void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler ModelAndView m):在当前请求被处理之后,在DispatcherServlet进行视图渲染前调用;该方法只有在preHandle返回true时才会执行;postHandle方法被调用的方向跟preHandle相反,即后声明的Interceptor的postHandle反而会先执行。
2.1.3 void afterHandle(HttpServletRequest request, HttpServletResponse response, Object handler,Exception e):该方法只有在preHandle返回true时才会执行,顾名思义,该方法在请求结束之后,即视图被渲染之后才会执行,主要作用是进行资源清理。
3.拦截器实现用户登录拦截
3.1 功能描述:用户必须登录才能访问应用页面,若没有登录直接访应用任何地址或者session过期,都会被拦截器拦截请求,跳转至登录页,提示用户登录;
3.2 定义LoginInterceptor实现类实现HandleInterceptor接口:
package org.aaron.framework.common.interceptor;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.aaron.framework.common.Constants;
import org.aaron.sysMgr.sysUser.entity.SysUser;
import org.apache.cxf.transport.http.policy.NoOpPolicyInterceptorProvider;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
public class LoginInterceptor implements HandlerInterceptor{
private String[] noInterceptors = {"/login/toLogin.do","/login/login.do","/sysUser/toRegister.do","/sysUser/register.do"};
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
String requestUrl = request.getServletPath();
System.out.println("=========:"+requestUrl);
String isAjax = request.getHeader("X-Requested-With");
String ctx = request.getServletContext().getContextPath();
if (Arrays.asList(noInterceptors).contains(requestUrl)) {
return true;
}
SysUser sysUser = (SysUser) request.getSession().getAttribute(Constants.CURRENT_USER);
if (sysUser == null) {
/*if (isAjax !=null && isAjax.equals("XMLHttpRequest")) {
Map<String,Object> resultMap = new HashMap<>();
resultMap.put("status",0);
resultMap.put("msg", Constants.NO_LOGIN);
resultMap.put("isLogin", false);
resultMap.put("url", ctx);
}*/
PrintWriter writer = response.getWriter();
response.setContentType("text/html;charset=utf-8");
writer.print("<script type='text/javascript'>alert('登录信息过期,请重新登录!');top.location='"+ctx+"/login/toLogin.do'</script> ");
writer.close();
}
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
// TODO Auto-generated method stub
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
// TODO Auto-generated method stub
}
}
3.3 在springmvc.xml(SpringMVC 配置文件)中配置拦截器:
<mvc:interceptors>
<bean class="org.aaron.framework.common.interceptor.LoginInterceptor"></bean>
</mvc:interceptors>