总体思想： 1.前台网页用js得到裁剪图片的id及x,y，宽度和高度。 2.服务端根据id取出要裁剪的图片 。 3.根据这些参数来生成裁剪的图像。-The general thinking of: 1. Front page to be cut by js picture id and x, y, width and height. 2. Server-side to cut out under the id of the picture. 3. Based on