springMVC拦截器HandlerInterceptor初步理解事例

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<pre name="code" class="java"><pre name="code" class="java">package com.interceptor;import java.io.IOException;import java.io.PrintWriter;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;import com.alibaba.fastjson.JSONObject;import com.util.StringUtil;import com.util.crypt.MD5UserInfo;public class UserInfoInterceptor implements HandlerInterceptor{/** * 该方法也是需要当前对应的Interceptor 的preHandle 方法的返回值为true 时才会执行。 * 该方法将在整个请求结束之后，也就是在DispatcherServlet 渲染了对应的视图之后执行。 * 这个方法的主要作用是用于进行资源清理工作的 */@Overridepublic void afterCompletion(HttpServletRequest req,HttpServletResponse res, Object object, Exception e)throws Exception {// TODO Auto-generated method stub}/** * 在当前请求进行处理之后，也就是Controller 方法调用之后执行， * 但是它会在DispatcherServlet 进行视图返回渲染之前被调用， * 所以可以在这个方法中对Controller 处理之后的ModelAndView 对象进行操作 */@Overridepublic void postHandle(HttpServletRequest req, HttpServletResponse res,Object object, ModelAndView mv) throws Exception {// TODO Auto-generated method stub}/** * handler方法调用前触发,返回false时，将不会继续执行请求的方法 */@Overridepublic boolean preHandle(HttpServletRequest req, HttpServletResponse res,Object object) throws Exception {// TODO Auto-generated method stubJSONObject msg = new JSONObject();HttpServletRequest httpservletrequest = (HttpServletRequest)req;        HttpServletResponse httpservletresponse = (HttpServletResponse)res;        HttpSession httpsession = httpservletrequest.getSession();        String param1 = (String) httpservletrequest.getParameter("param1");//获取链接请求参数        String param2 = (String) httpservletrequest.getParameter("param2");        String param3 = (String) httpservletrequest.getParameter("param3");        if(!StringUtil.isEmpty(param1)){        if(!StringUtil.isEmpty(param2)){        if(!StringUtil.isEmpty(param3)){        if(UserInfo.vailUserInfo(param1, param2, param3)){                    return true;                }else{                msg.put("code", 1);                msg.put("info", "请求参数有误4");                }            }else{                   msg.put("code", 1);                   msg.put("info", "请求参数有误3");            }        }else{                msg.put("code", 1);                msg.put("info", "请求参数有误2");        }                }else{            msg.put("code", 1);            msg.put("info", "请求参数有误1");        }        out(msg.toJSONString(), res);<span style="white-space:pre"></span>//如果不符合要求，返回对应提示    return false;}public static String out(String msg,HttpServletResponse res) {res.setContentType("text/html; charset=utf-8");try {PrintWriter out = res.getWriter();out.print(msg);out.flush();out.close();} catch (IOException e) {e.printStackTrace();}return null;}}

在将拦截器注入进spring中

<span style="white-space:pre"></span><beanclass="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"><property name="interceptors"><list><bean class="com.interceptor.UserInfoInterceptor"/></list></property></bean>

在web.xml中配置springmvc

<servlet>    <servlet-name>XXX</servlet-name>    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>    <init-param>    <param-name>contextConfigLocation</param-name>    <param-value>/WEB-INF/servlet.xml</param-value>    </init-param>    <load-on-startup>1</load-on-startup></servlet><servlet-mapping>    <servlet-name>XXX</servlet-name>    <url-pattern>/</url-pattern></servlet-mapping>

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