慢慢发现在诸多技能中，coding是最不应该花时间的。 在代码编写前，和代码编写后的事情，往往才是重要的。 想清楚你要做什么，要怎么做，以及之后要达成什么样的目标，检验结果是否符合预期 这些事情，都应该比coding要重要。 没有人愿意去读你的代码，除非没办法。 想写一系列的pre coding 和 post coding 的文章。今天开个头，希望能持续写下去
UML–让你的需求清晰的法宝
首先说明，我不用图形界面拖拽控件来画流程图。诸如`Visio` `Precess On`我一律不用。
原因很简单，我认为拖拽的效率非常低，你大量的精力都花在元素是否对其，鼠标和键盘之间来回切换,
你反而不能集中精力去思考逻辑。还有一个原因，不利于复用和修改。
plantuml
plantuml是一个开源的工具，你可以用它来画流程图，用例图 类图等等。最令人满意的是，你可以用写代码的模式来“画”uml图。 比如：
1.创建一个demo.uml的文件,用你习惯的编辑器，编写如下内容：
@startuml
client->server: syn=1 seq=x
note left
客户端发送syn报文,
发送序列号为x
end note
client<-server: syn=1 ack=x+1 seq=y
note right
服务端接受请求， 回复syn+ack报文，
并置发送序列号为y,确认序列号为x+1
end note
client->server: ack=y+1 seq=z
note left
客户端发送ack报文,并置发送序列号为z
确认序列号为y+1
end note
@enduml
2.下载plantuml.jar包
http://sourceforge.net/projects/plantuml/files/plantuml.jar/download
3.把plantuml.jar移动到你乐意的路径下,并创建一个可执行文件plantuml文件
linux下参考如下操作:
mv ./plantuml.jar /usr/local/bin/plantuml.jar
touch /usr/local/bin/plantuml
echo "#!/bin/bash" >> /usr/local/bin/plantuml
echo "jar -jar /usr/local/bin/plantuml.jar $@" >> /usr/local/bin/plantuml
chmod +x /usr/local/bin/plantuml
4.查看plantuml的帮助plantuml -h,结果如下
Usage: java -jar plantuml.jar [options] -gui
(to execute the GUI)
or java -jar plantuml.jar [options] [file/dir] [file/dir] [file/dir]
(to process files or directories)
You can use the following wildcards in files/dirs:
* means any characters but '/'
? one and only one character but '/'
** means any characters (used to recurse through directories)
where options include:
-gui To run the graphical user interface
-tpng To generate images using PNG format (default)
-tsvg To generate images using SVG format
-teps To generate images using EPS format
-tpdf To generate images using PDF format
-tvdx To generate images using VDX format
-txmi To generate XMI file for class diagram
-tscxml To generate SCXML file for state diagram
-thtml To generate HTML file for class diagram
-ttxt To generate images with ASCII art
-tutxt To generate images with ASCII art using Unicode characters
-tlatex To generate images using LaTeX/Tikz format
-tlatex:nopreamble To generate images using LaTeX/Tikz format without preamble
-o[utput] "dir" To generate images in the specified directory
-DVAR1=value To set a preprocessing variable as if '!define VAR1 value' were used
-Sparam1=value To set a skin parameter as if 'skinparam param1 value' were used
-r[ecurse] recurse through directories
-I/path/to/file To include file as if '!include file' were used
-I/path/to/*.puml To include files with pattern
-charset xxx To use a specific charset (default is UTF-8)
-e[x]clude pattern To exclude files that match the provided pattern
-metadata To retrieve PlantUML sources from PNG images
-nometadata To NOT export metadata in PNG/SVG generated files
-checkmetadata Skip PNG files that don't need to be regenerated
-version To display information about PlantUML and Java versions
-checkversion To check if a newer version is available for download
-v[erbose] To have log information
-quiet To NOT print error message into the console
-debugsvek To generate intermediate svek files
-h[elp] To display this help message
-testdot To test the installation of graphviz
-graphvizdot "exe" To specify dot executable
-p[ipe] To use stdin for PlantUML source and stdout for PNG/SVG/EPS generation
-encodesprite 4|8|16[z] "file" To encode a sprite at gray level (z for compression) from an image
-computeurl|-encodeurl To compute the encoded URL of a PlantUML source file
-decodeurl To retrieve the PlantUML source from an encoded URL
-syntax To report any syntax error from standard input without generating images
-language To print the list of PlantUML keywords
-checkonly To check the syntax of files without generating images
-failfast To stop processing as soon as a syntax error in diagram occurs
-failfast2 To do a first syntax check before processing files, to fail even faster
-pattern To print the list of Regular Expression used by PlantUML
-duration To print the duration of complete diagrams processing
-nbthread N To use (N) threads for processing
-nbthread auto To use 4 threads for processing
-timeout N Processing timeout in (N) seconds. Defaults to 15 minutes (900 seconds).
-author[s] To print information about PlantUML authors
-overwrite To allow to overwrite read only files
-printfonts To print fonts available on your system
-enablestats To enable statistics computation
-disablestats To disable statistics computation (default)
-htmlstats To output general statistics in file plantuml-stats.html
-xmlstats To output general statistics in file plantuml-stats.xml
-realtimestats To generate statistics on the fly rather than at the end
-loopstats To continuously print statistics about usage
-splash To display a splash screen with some progress bar
-progress To display a textual progress bar in console
-pipeimageindex N To generate the Nth image with pipe option
-stdlib To print standard library info
-extractstdlib To extract PlantUML Standard Library into stdlib folder
-filename "example.puml" To override %filename% variable
-preproc To output preprocessor text of diagrams
-cypher To cypher texts of diagrams so that you can share them
If needed, you can setup the environment variable GRAPHVIZ_DOT.
5.把刚才写的uml文件输出为png或其他格式
plantuml -tpng test.uml 图片如下：
输出一个文本的图plantuml -tutxt test.uml
┌──────┐ ┌──────┐
│client│ │server│
└──┬───┘ └──┬───┘
╔════════════════════╗│ syn=1 seq=x │
║客户端发送syn报文, ░║│ ───────────────────>
║发送序列号为x ║│ │
╚════════════════════╝│ │
│ syn=1 ack=x+1 seq=y│ ╔════════════════════════════════════╗
│ <─────────────────── ║服务端接受请求， 回复syn+ack报文， ░║
│ │ ║并置发送序列号为y,确认序列号为x+1 ║
│ │ ╚════════════════════════════════════╝ ╔═════════════════════════════════════╗│ ack=y+1 seq=z │ ║客户端发送ack报文,并置发送序列号为z ░║│ ───────────────────> ║确认序列号为y+1 ║│ │ ╚═════════════════════════════════════╝┴───┐ ┌──┴───┐
│client│ │server│
└──────┘ └──────┘