Java_web_request.setattribute ("result", username);

Request.setattribute ("result", username);
    Add a property named result to the request object with a value of username, because the request object can be changed, and you can access the property in the same request like this.
Although similar to the session, but with the session is different,Request.setattribute set of properties can only be used in the current request , such as you set the result property in action, Needs to be read in the JSP page:

Request.setattribute ("result", username), Requests.getrequestdispatcher ("result.jsp"). Forward (Request, Response);

The JSP page gets the value:
Request.getattribute ("result");

Because the request of the current action and the response object are sent together, it is equivalent to directly manipulating its own page.

Java_web_request.setattribute ("result", username);