一、XML约束
### --- XML约束介绍
——> 在XML技术里,可以编写一个文档来约束一个XML文档的书写规范,这称之为XML约束。
~~~ # 常见的xml约束:
——> DTD
——> Schema
~~~ # 作为程序员只要掌握两点
——> 会阅读
——> 会引入
——> 不用自己编写
![](https://img.laitimes.com/img/_0nNw4CM6IyYiwiM6ICdiwiI0gTMx81dsQWZ4lmZf1GLlpXazVmcvwFciV2dsQXYtJ3bm9CX9s2RkBnVHFmb1clWvB3MaVnRtp1XlBXe0xCMy81dvRWYoNHLwEzX5xCMx8FesU2cfdGLwMzX0xiRGZkRGZ0Xy9GbvNGLpZTY1EmMZVDUSFTU4VFRR9Fd4VGdsYTMfVmepNHLrJXYtJXZ0F2dvwVZnFWbp1zczV2YvJHctM3cv1Ce-cGcq5SMyUTO0MzNkRWN1kDNkVTNyYzX5QTNzMDMzEzLcRDMyIDMy8CXn9Gbi9CXzV2Zh1WavwVbvNmLvR3YxUjLyM3Lc9CX6MHc0RHaiojIsJye.jpg)
Walter Savage Landor:strove with none,for none was worth my strife.Nature I loved and, next to Nature, Art:I warm'd both hands before the fire of life.It sinks, and I am ready to depart
——W.S.Landor