安装Graphviz2.38，环境变量设置

C:\Users>dot -version
'dot' 不是内部或外部命令，也不是可运行的程序
或批处理文件。

C:\Users>cd ..

C:\>SET Path=C:\Program Files (x86)\Graphviz2.38\bin

C:\>dot -version
dot - graphviz version 2.38.0 (20140413.2041)
libdir = "C:\Program Files (x86)\Graphviz2.38\bin"
Activated plugin library: gvplugin_dot_layout.dll
Using layout: dot:dot_layout
Activated plugin library: gvplugin_core.dll
Using render: dot:core
Using device: dot:dot:core
The plugin configuration file:
        C:\Program Files (x86)\Graphviz2.38\bin\config6
                was successfully loaded.
    render      :  cairo dot fig gd gdiplus map pic pov ps svg tk vml vrml xdot
    layout      :  circo dot fdp neato nop nop1 nop2 osage patchwork sfdp twopi
    textlayout  :  textlayout
    device      :  bmp canon cmap cmapx cmapx_np dot emf emfplus eps fig gd gd2 gif gv imap imap_np ismap jpe jpeg jpg metafile pdf pic plain plain-ext png pov ps ps2 svg svgz tif tiff tk vml vmlz vrml wbmp xdot xdot1.2 xdot1.4
    loadimage   :  (lib) bmp eps gd gd2 gif jpe jpeg jpg png ps svg