java8 动态编译保留方法参数名字

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编译保留方法参数名字

javac 文档

javac doc

-parameters
      Stores formal parameter names of constructors and methods in the generated class file so that the method java.lang.reflect.Executable.getParameters from the Reflection API can retrieve them. 

获取动态编译支持的参数列表

反射获取参数名这个问题本身和解决的方法很简单，但动态编译相关资料和问题不多，也没有找到介绍动态编译时 options 相关参数的文章和问题，此处做一下记录，方便参考 。

调用 JavaCompiler 接口的 getTask 方法时，可以使用参数 options

CompilationTask getTask(Writer out,
                            JavaFileManager fileManager,
                            DiagnosticListener<? super JavaFileObject> diagnosticListener,
                            Iterable<String> options,
                            Iterable<String> classes,
                            Iterable<? extends JavaFileObject> compilationUnits);

参数列表

获取 option 参数列表的方法如下

断点打在 processArgs 方法上，执行 Evaluate Expression 片段 com.sun.tools.javac.main.Main.processArgs 此处类引用和参数类型出现缺失，IDE 报红，不能在一行完成循环打印

for (int p=0;p<recognizedOptions.length;p++) {
    System.out.print(recognizedOptions[p].name);
    System.out.print("\t");
    System.out.print(recognizedOptions[p].text);
    System.out.print("\t");
    System.out.print(recognizedOptions[p].descrKey+"");
    System.out.print("\t");
    System.out.print(recognizedOptions[p].group.name+"");
    System.out.print("\t");
    System.out.printf(recognizedOptions[p].kind.name+"");
    System.out.println();
}

recognizedOptions

输出

共有61个参数，第二列是 option 参数名称和格式，详细释义和 demo 见开头的 javac 官方文档

G	-g	opt.g	BASIC	STANDARD
G_NONE	-g:none	opt.g.none	BASIC	STANDARD
G_CUSTOM	-g:	opt.g.lines.vars.source	BASIC	STANDARD
XLINT	-Xlint	opt.Xlint	BASIC	EXTENDED
XLINT_CUSTOM	-Xlint:	opt.Xlint.suboptlist	BASIC	EXTENDED
XDOCLINT	-Xdoclint	opt.Xdoclint	BASIC	EXTENDED
XDOCLINT_CUSTOM	-Xdoclint:	opt.Xdoclint.custom	BASIC	EXTENDED
NOWARN	-nowarn	opt.nowarn	BASIC	STANDARD
VERBOSE	-verbose	opt.verbose	BASIC	STANDARD
DEPRECATION	-deprecation	opt.deprecation	BASIC	STANDARD
CLASSPATH	-classpath	opt.classpath	FILEMANAGER	STANDARD
CP	-cp	opt.classpath	FILEMANAGER	STANDARD
SOURCEPATH	-sourcepath	opt.sourcepath	FILEMANAGER	STANDARD
BOOTCLASSPATH	-bootclasspath	opt.bootclasspath	FILEMANAGER	STANDARD
XBOOTCLASSPATH_PREPEND	-Xbootclasspath/p:	opt.Xbootclasspath.p	FILEMANAGER	EXTENDED
XBOOTCLASSPATH_APPEND	-Xbootclasspath/a:	opt.Xbootclasspath.a	FILEMANAGER	EXTENDED
XBOOTCLASSPATH	-Xbootclasspath:	opt.bootclasspath	FILEMANAGER	EXTENDED
EXTDIRS	-extdirs	opt.extdirs	FILEMANAGER	STANDARD
DJAVA_EXT_DIRS	-Djava.ext.dirs=	opt.extdirs	FILEMANAGER	EXTENDED
ENDORSEDDIRS	-endorseddirs	opt.endorseddirs	FILEMANAGER	STANDARD
DJAVA_ENDORSED_DIRS	-Djava.endorsed.dirs=	opt.endorseddirs	FILEMANAGER	EXTENDED
PROC	-proc:	opt.proc.none.only	BASIC	STANDARD
PROCESSOR	-processor	opt.processor	BASIC	STANDARD
PROCESSORPATH	-processorpath	opt.processorpath	FILEMANAGER	STANDARD
PARAMETERS	-parameters	opt.parameters	BASIC	STANDARD
D	-d	opt.d	FILEMANAGER	STANDARD
S	-s	opt.sourceDest	FILEMANAGER	STANDARD
H	-h	opt.headerDest	FILEMANAGER	STANDARD
IMPLICIT	-implicit:	opt.implicit	BASIC	STANDARD
ENCODING	-encoding	opt.encoding	FILEMANAGER	STANDARD
SOURCE	-source	opt.source	BASIC	STANDARD
TARGET	-target	opt.target	BASIC	STANDARD
PROFILE	-profile	opt.profile	BASIC	STANDARD
VERSION	-version	opt.version	INFO	STANDARD
FULLVERSION	-fullversion	null	INFO	HIDDEN
DIAGS	-XDdiags=	null	INFO	HIDDEN
HELP	-help	opt.help	INFO	STANDARD
A	-A	opt.A	BASIC	STANDARD
X	-X	opt.X	INFO	STANDARD
J	-J	opt.J	INFO	STANDARD
MOREINFO	-moreinfo	null	BASIC	HIDDEN
WERROR	-Werror	opt.Werror	BASIC	STANDARD
PROMPT	-prompt	null	BASIC	HIDDEN
DOE	-doe	null	BASIC	HIDDEN
PRINTSOURCE	-printsource	null	BASIC	HIDDEN
WARNUNCHECKED	-warnunchecked	null	BASIC	HIDDEN
XMAXERRS	-Xmaxerrs	opt.maxerrs	BASIC	EXTENDED
XMAXWARNS	-Xmaxwarns	opt.maxwarns	BASIC	EXTENDED
XSTDOUT	-Xstdout	opt.Xstdout	INFO	EXTENDED
XPRINT	-Xprint	opt.print	BASIC	EXTENDED
XPRINTROUNDS	-XprintRounds	opt.printRounds	BASIC	EXTENDED
XPRINTPROCESSORINFO	-XprintProcessorInfo	opt.printProcessorInfo	BASIC	EXTENDED
XPREFER	-Xprefer:	opt.prefer	BASIC	EXTENDED
XPKGINFO	-Xpkginfo:	opt.pkginfo	BASIC	EXTENDED
O	-O	null	BASIC	HIDDEN
XJCOV	-Xjcov	null	BASIC	HIDDEN
PLUGIN	-Xplugin:	opt.plugin	BASIC	EXTENDED
XDIAGS	-Xdiags:	opt.diags	BASIC	EXTENDED
XD	-XD	null	BASIC	HIDDEN
AT	@	opt.AT	INFO	STANDARD
SOURCEFILE	sourcefile	null	INFO	HIDDEN

验证参数名字

粗略验证，如果输出的参数名不是 arg0 和 arg1 这种格式则说明设置生效

Stream.of(clz.getDeclaredMethods()).forEach(
        method -> {
           Stream.of( method.getParameters()).forEach(
               parameter ->     {
                           System.out.printf("%s( %s,%s,%s)\n",method.getName(),parameter.getName(),
                                   parameter.getRealName(),parameter.isVarArgs());
                   }
           );
        }
);   

来源：oschina

链接：https://my.oschina.net/ois/blog/3146965