Jsp a click on the verification code to refresh the code, do not understand.

This is a picture, which refers to a JSP page, and the verification code generated by image.jsp is displayed on the picture of this page. SeeE method plays the role of refreshing the verification code, and redistributing the path to the picture is the refreshing effect, and the later time is caused by the caching mechanism of javascript. If you write Ajax login in pure code, you will know the principle. The same path will not send a second request to the background, and the milliseconds of time cannot be repeated, so each path is different. In addition, sometimes random numbers can be used.