一：javacjavac [ options ] [ sourcefiles ] [ @files ] 参数可按任意次序排列。
options 命令行选项。 sourcefiles 一个或多个要编译的源文件（例如 MyClass.java）。 @files 一个或多个对源文件进行列表的文件。 例如一个名字为mysource.txt文本文档有如下内容： C:/javaTest/src/com/abc/HelloWorld.java C:/javaTest/src/com/abc/SayHelloWorld.java 则可以使用javac @mysource.txt对mysource.txt内列出的java文件进行编译。
在dos命令窗口下可以通过javac命令还直接查看JDK自带的命令参数说明：C:/javaTest>javacUsage: javac <options> <source files>where possible options include: -g Generate all debugging info -g:none Generate no debugging info -g:{lines,vars,source} Generate only some debugging info -nowarn Generate no warnings -verbose Output messages about what the compiler is doing -deprecation Output source locations where deprecated APIs are used -classpath <path> Specify where to find user class files and annotation processors -cp <path> Specify where to find user class files and annotation processors -sourcepath <path> Specify where to find input source files -bootclasspath <path> Override location of bootstrap class files -extdirs <dirs> Override location of installed extensions -endorseddirs <dirs> Override location of endorsed standards path -proc:{none,only} Control whether annotation processing and/or compilation is done. -processor <class1>[,<class2>,<class3>...]Names of the annotation processors to run; bypasses default discovery process -processorpath <path> Specify where to find annotation processors -d <directory> Specify where to place generated class files -s <directory> Specify where to place generated source files -implicit:{none,class} Specify whether or not to generate class files for implicitly referenced files -encoding <encoding> Specify character encoding used by source files -source <release> Provide source compatibility with specified release -target <release> Generate class files for specific VM version -version Version information -help Print a synopsis of standard options -Akey[=value] Options to pass to annotation processors -X Print a synopsis of nonstandard options -J<flag> Pass <flag> directly to the runtime system
值得一提的是-d选项，-d选项用来指定编译生成的类文件的存放路径，但是javac命令不会生成这个路径，必须确保该路径已经存在。另外，使用-d选项后，javac命令会自动生成java文件里package语句声明的包路径（一些文件夹）。
例如有HelloWorld.java文件：package com.abc;public class HelloWorld{ public static void main(String args[]){ System.out.println("hello world!"); }}放在C:/javaTest/src/com/abc内，C:/javaTest>tree /fFolder PATH listing for volume APACCNDLBIW1003Volume serial number is 1877-06AAC:.├─classes└─src └─com └─abc HelloWorld.java
C:/javaTest>cd srcC:/javaTest/src>javac -classpath .;%classpath% -d C:/javaTest/classes com/abc/HelloWorld.javaC:/javaTest/src>cd ..
C:/javaTest>tree /fFolder PATH listing for volume APACCNDLBIW1003Volume serial number is 1877-06AAC:.├─classes│ └─com│ └─abc│ HelloWorld.class│└─src └─com └─abc HelloWorld.java
C:/javaTest>
可以看到javac命令在-d指定的路径C:/javaTest/classes内生成了com.abc.HelloWorld.class文件。
