Detailed explanation of interception examples of interceptors on ajax requests

Solve the interception of ajax requests by the interceptor

Interceptor configuration:

public boolean preHandle(HttpServletRequest request, HttpServletResponse response,Object obj) throws Exception {
     
    //获取判定登陆的session是否存在
    String token = (String) request.getSession().getAttribute("token");
    String postId = (String) request.getSession().getAttribute("postId");
    if(token == null || token == ""){
      String XRequested =request.getHeader("X-Requested-With");
      if("XMLHttpRequest".equals(XRequested)){
        response.getWriter().write("IsAjax");
      }else{
        response.sendRedirect("/m-web/user/toLogin");
      }
      return false;
    }
    if(postId == null || postId == ""){
      String XRequested =request.getHeader("X-Requested-With");
      if("XMLHttpRequest".equals(XRequested)){
        response.getWriter().write("IsAjax");
      }else{
        response.sendRedirect("/m-web/user/toLogin");
      }
      return false;
    }
    return true;
  }

1. Determine String XRequested =request.getHeader("X-Requested-With") The value is to determine whether it is an ajax request.

2. response.getWriter().write("IsAjax"); Write a response data to ajax, so that you can make a judgment in ajax.

There are two ways to judge. Method:

1) Make judgment directly in ajax (not recommended)

success:function(data){
  if(data == "IsAjax"){
    window.location.href="m-web/user/toLogin"
    return;
  }
}

2) Change the ajax source code and then perform compression, which is modified in a global way (recommended)

if ( isSuccess ) {// if no content
       if ( status === 204 || s.type === "HEAD" ) {
         statusText = "nocontent";
 
       // if not modified
       } else if ( status === 304 ) {
         statusText = "notmodified";
 
       // If we have data, let's convert it
       } else {
         statusText = response.state;
         success = response.data;
         error = response.error;
         isSuccess = !error;
         //解决ajax拦截问题
         var result = responses.text;
         if(result.indexOf("IsAjax")>=0){
           window.location.href="m-web/user/toLogin";
           return;
         }
       }
     }

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For more detailed examples of interception of ajax requests by interceptors, please pay attention to the PHP Chinese website for related articles!

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