拦截器拦截 ajax代码，以及乱码处理

来源：互联网发布：政府集中采购流程知乎编辑：程序博客网时间：2024/06/09 22:14

今天又学得了如何用拦截器拦截ajax，原来是异步的原因，所以要用不同的处理方法。之前用普通的拦截器，出现的现象就是跟没用拦截器时的一样。

首先要明白：

普通请求与ajax请求的报文头不一样，通过如下

String requestType = request.getHeader("X-Requested-With");
如果requestType能拿到值，并且值为XMLHttpRequest,表示客户端的请求为异步请求，那自然是ajax请求了，反之如果为null,则是普通的请求

以下是验证登陆的拦截器，代码如下：

package com.bossin.vote.interceptor;

import java.io.PrintWriter;

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

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;

public class VoteInterceptor implements Interceptor {
   private static final long serialVersionUID = 1L;

   public void destroy() {
   }

   public void init() {
   }

   public String intercept(ActionInvocation invocation) throws Exception {
       HttpServletRequest req = ServletActionContext.getRequest();

       if(req.getSession().getAttribute("login_account")==null){
           HttpServletResponse response = ServletActionContext.getResponse();
           PrintWriter pw = response.getWriter();
           String flag = "";

           if (req.getHeader("X-Requested-With") != null
                   && req.getHeader("X-Requested-With").equalsIgnoreCase(
                   "XMLHttpRequest")) {
                       response.setCharacterEncoding("text/html;charset=utf-8");
                       response.setContentType("text/html;charset=utf-8");
                       flag = "请先登录";
                       pw.write(flag);
                       return null;
           }

       }
       return invocation.invoke();

   }
}

struts.xml 配置跟普通的拦截器就是少了返回页面的设置，具体配置如下：

按上面的代码是可以实现功能的，但会出现前台弹出的窗口出现中文乱码。

个人做以下处理便解决了中文乱码：即把编码设置放在 PrintWriter pw = response.getWriter();前面

package com.bossin.vote.interceptor;

import java.io.PrintWriter;

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

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;

public class VoteInterceptor implements Interceptor {
   private static final long serialVersionUID = 1L;

   public void destroy() {
   }

   public void init() {
   }

   public String intercept(ActionInvocation invocation) throws Exception {
       HttpServletRequest req = ServletActionContext.getRequest();

       if(req.getSession().getAttribute("login_account")==null){
           HttpServletResponse response = ServletActionContext.getResponse();

           if (req.getHeader("X-Requested-With") != null
                   && req.getHeader("X-Requested-With").equalsIgnoreCase(
                   "XMLHttpRequest")) {
                       response.setCharacterEncoding("text/html;charset=utf-8");
                       response.setContentType("text/html;charset=utf-8"); //这两句得放在pw前，否则出现乱码
                       PrintWriter pw = response.getWriter();
                       String flag = "请先登录";
                       pw.write(flag);
                       return null;
           }

       }
       return invocation.invoke();

   }
}

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