ant+yuicompressor压缩js/css

ant+yuicompressor在前端部署和服务器发布中用处极大。我在项目中用到的是ant+yuicompressor，ant可以压缩CSS，压缩javascript,并可以传输信息和远程服务器发布！
目前yuicompressor最新版本为yuicompressor-2.4.8.jar，请使用该版本的jar。因为我使用2.4.7版本后，出现了混淆后的js代码替换环境后使用有问题，而使用2.4.8版本混淆出来的js代码替换环境后则正常。
下载地址：yuicompressor-2.4.8.jar

一、在github上查看yuicompressor的源码

https://github.com/yui/yuicompressor

二、在官网上查看yuicompressor的使用说明

http://yui.github.io/yuicompressor/
通用参数：
-h, –help 显示帮助信息
–type 指定输入文件的文件类型
–charset 指定读取输入文件使用的编码
–line-break 在指定的列后插入一个 line-bread 符号
-v, –verbose 显示info和warn级别的信息
-o 指定输出文件。默认输出是控制台。

JavaScript专用参数：
–nomunge 只压缩, 不对局部变量进行混淆。
–preserve-semi 保留所有的分号。
–disable-optimizations 禁止优化。

详情如下：

java -jar yuicompressor-x.y.z.jar
Usage: java -jar yuicompressor-x.y.z.jar [options] [input file]

  Global Options
    -h, --help                Displays this information
    --type            Specifies the type of the input file
    --charset        Read the input file using 
    --line-break      Insert a line break after the specified column number
    -v, --verbose             Display informational messages and warnings
    -o                  Place the output into  or a file pattern.
                              Defaults to stdout.

  JavaScript Options
    --nomunge                 Minify only, do not obfuscate
    --preserve-semi           Preserve all semicolons
    --disable-optimizations   Disable all micro optimizations

GLOBAL OPTIONS

  -h, --help
      Prints help on how to use the YUI Compressor

  --line-break
      Some source control tools don't like files containing lines longer than,
      say 8000 characters. The linebreak option is used in that case to split
      long lines after a specific column. It can also be used to make the code
      more readable, easier to debug (especially with the MS Script Debugger)
      Specify 0 to get a line break after each semi-colon in JavaScript, and
      after each rule in CSS.

  --type js|css
      The type of compressor (JavaScript or CSS) is chosen based on the
      extension of the input file name (.js or .css) This option is required
      if no input file has been specified. Otherwise, this option is only
      required if the input file extension is neither 'js' nor 'css'.

  --charset character-set
      If a supported character set is specified, the YUI Compressor will use it
      to read the input file. Otherwise, it will assume that the platform's
      default character set is being used. The output file is encoded using
      the same character set.

  -o outfile

      Place output in file outfile. If not specified, the YUI Compressor will
      default to the standard output, which you can redirect to a file.
      Supports a filter syntax for expressing the output pattern when there are
      multiple input files.  ex:
          java -jar yuicompressor.jar -o '.css$:-min.css' *.css
      ... will minify all .css files and save them as -min.css

  -v, --verbose
      Display informational messages and warnings.

JAVASCRIPT ONLY OPTIONS

  --nomunge
      Minify only. Do not obfuscate local symbols.

  --preserve-semi
      Preserve unnecessary semicolons (such as right before a '}') This option
      is useful when compressed code has to be run through JSLint (which is the
      case of YUI for example)

  --disable-optimizations
      Disable all the built-in micro optimizations.

可以使用java命令调用方式，例如：

java -jar yuicompressor-x.y.z.jar myfile.js -o myfile-min.js
java -jar yuicompressor-x.y.z.jar myfile.js -o myfile-min.js --charset utf-8

三、在ant中配置yuicompressor进行js和css的压缩步骤

1、配置yuicompressor包的版本号

打开ivy-versions.properties文件，增加如下配置

/com.yahoo.platform.yui/yuicompressor = 2.4.8

2、配置依赖yuicompressor包的配置

打开ivy.xml文件，增加依赖yuicompressor包的配置，以便于执行ant时自动下载该jar包。

3、配置js文件和ccs文件压缩的配置

打开build.xml文件，增加调用yuicompressor包对js文件和ccs文件压缩的配置。

常见问题：

1、使用yuicompressor压缩js时报错的解决方案

$ java -jar /C/Users/wkh/Downloads/yuicompressor-2.4.8.jar -o '.js$:-min.js' *.js --charset utf-8 --nomunge
[ERROR] in analysis.js
  47:18:missing variable name
[ERROR] in analysis.js
  49:27:syntax error
[ERROR] in analysis.js
  50:21:identifier is a reserved word
[ERROR] in analysis.js
  104:26:invalid property id
[ERROR] in analysis.js
  104:27:syntax error
[ERROR] in analysis.js
  105:30:syntax error
[ERROR] in analysis.js
  106:28:syntax error
[ERROR] in analysis.js
  1:0:Compilation produced 7 syntax errors.
org.mozilla.javascript.EvaluatorException: Compilation produced 7 syntax errors.
        at com.yahoo.platform.yui.compressor.YUICompressor$1.runtimeError(YUICompressor.java:172)
        at org.mozilla.javascript.Parser.parse(Parser.java:396)
        at org.mozilla.javascript.Parser.parse(Parser.java:340)
        at com.yahoo.platform.yui.compressor.JavaScriptCompressor.parse(JavaScriptCompressor.java:315)
        at com.yahoo.platform.yui.compressor.JavaScriptCompressor.(JavaScriptCompressor.java:536)
        at com.yahoo.platform.yui.compressor.YUICompressor.main(YUICompressor.java:147)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at com.yahoo.platform.yui.compressor.Bootstrap.main(Bootstrap.java:21)

报错主要是因为js源文件中有js关键字和保留字定义的变量或参数。因此可以将这些变量名进行变更，将参数用['parameter']的方式替换。
例如：
（1）变更变量名

        var short = -1 !== longname.indexOf( '$' )
                         ? longname.split( '$' )[1]
                         : longname.split( '.' ).pop();
        return short.match( /[A-Z]/g ).join( '' );

变量名short是js保留字，可以修改为shortComponentName。

        var shortComponentName = -1 !== longname.indexOf( '$' )
                         ? longname.split( '$' )[1]
                         : longname.split( '.' ).pop();
        return shortComponentName.match( /[A-Z]/g ).join( '' );

（2）变更参数获取方式

 logger.short = shortNameOf(logger);

将.short参数用['short']的方式替换

logger['short'] = shortNameOf(logger);

2、如何跳过许可/信用时的注释，使用YUIcompressor压缩JavaScript？

按照如下方式对许可/信用进行注释，感叹号告诉压缩器保留注释。

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