update structure

Book/structure.tex

@@ -615,8 +615,21 @@ addtohook={%
 \definecolor{xtgreen}{rgb}{0.914,0.945,0.902}
 \definecolor{lightgray}{gray}{0.85}
 
-
-
+%%%%%%%%%%%%appendix-------------------------------
+\makeatletter
+\def\UrlAlphabet{%
+      \do\a\do\b\do\c\do\d\do\e\do\f\do\g\do\h\do\i\do\j%
+      \do\k\do\l\do\m\do\n\do\o\do\p\do\q\do\r\do\s\do\t%
+      \do\u\do\v\do\w\do\x\do\y\do\z\do\A\do\B\do\C\do\D%
+      \do\E\do\F\do\G\do\H\do\I\do\J\do\K\do\L\do\M\do\N%
+      \do\O\do\P\do\Q\do\R\do\S\do\T\do\U\do\V\do\W\do\X%
+      \do\Y\do\Z}
+\def\UrlDigits{\do\1\do\2\do\3\do\4\do\5\do\6\do\7\do\8\do\9\do\0}
+\g@addto@macro{\UrlBreaks}{\UrlOrds}%特殊符号
+\g@addto@macro{\UrlBreaks}{\UrlAlphabet}%26个字母表
+\g@addto@macro{\UrlBreaks}{\UrlDigits}%10个阿拉伯数字
+\makeatother
+%上述设置的作用是URL自动换行