windows windows上的unix“which java”等效命令？
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unix "which java" equivalent command on windows?
提问by Michael Mao
Possible Duplicate:
Is there an equivalent of ‘which' on windows?
可能的重复：
Windows 上是否有“which”的等价物？
Failed to find it on Google, but just wondering if there is a way to reveal location of java by an equivalent command from Windows prompt.
无法在 Google 上找到它，只是想知道是否有办法通过 Windows 提示符下的等效命令来显示 java 的位置。
Basically I have info from client that he doesn't set the JAVA_HOME but still can run java programs. I suspect it then must because the path to that java is set in the system PATH environment variable, but that is just too long to iterate in a quick way, also very painful (have to dig into sub-folders).
基本上我从客户那里得到信息，他没有设置 JAVA_HOME 但仍然可以运行 Java 程序。我怀疑它必须是因为该 java 的路径是在系统 PATH 环境变量中设置的，但这对于快速迭代来说太长了，也很痛苦（必须深入到子文件夹中）。
Thanks for any suggestion in advance!
感谢您提前提供任何建议！
回答by paxdiablo
You can try:
你可以试试：
c:\> for %i in (java.exe) do @echo. %~$PATH:i
C:\WINDOWS\system32\java.exe
This is a feature of the Windows forcommand and you can use for /?to get the details:
这是 Windowsfor命令的一个功能，您可以使用它for /?来获取详细信息：
In addition, substitution of FOR variable references has been enhanced.
You can now use the following optional syntax:
%~I - expands %I removing any surrounding quotes (")
%~fI - expands %I to a fully qualified path name
%~dI - expands %I to a drive letter only
%~pI - expands %I to a path only
%~nI - expands %I to a file name only
%~xI - expands %I to a file extension only
%~sI - expanded path contains short names only
%~aI - expands %I to file attributes of file
%~tI - expands %I to date/time of file
%~zI - expands %I to size of file
%~$PATH:I - searches the directories listed in the PATH
environment variable and expands %I to the
fully qualified name of the first one found.
If the environment variable name is not
defined or the file is not found by the
search, then this modifier expands to the
empty string
The modifiers can be combined to get compound results:
%~dpI - expands %I to a drive letter and path only
%~nxI - expands %I to a file name and extension only
%~fsI - expands %I to a full path name with short names only
%~dp$PATH:I - searches the directories listed in the PATH
environment variable for %I and expands to the
drive letter and path of the first one found.
%~ftzaI - expands %I to a DIR like output line
In the above examples %I and PATH can be replaced by other valid
values. The %~ syntax is terminated by a valid FOR variable name.
Picking upper case variable names like %I makes it more readable and
avoids confusion with the modifiers, which are not case sensitive.
回答by luiscolorado
Am I missing something here? What about trying the following simple command lines?
我在这里错过了什么吗？尝试以下简单的命令行怎么样？
c:>dir /s java.exe
c:>dir /s java.exe
or
或者
c:>dir /s javaw.exe
c:>dir /s javaw.exe
They will take time, but they will work. If you want to make it faster, start at "c:\Program files"
它们需要时间，但它们会起作用。如果你想让它更快，从“c:\Program files”开始
回答by Jerry Coffin
Here's what I normally use. If I were doing it again today, I'd probably do it a bit differently, but it works well enough that I haven't really had any reason to look at it for years (in fact, I'm pretty sure the last time I did anythingto it was adding "cmd" to the list of extensions when I ported it from DOS to Win32...
这是我通常使用的。如果我今天再做一次，我可能会做一些不同的事情，但它运行得很好，以至于我多年来一直没有任何理由去看它（事实上，我很确定上次当我将它从 DOS 移植到 Win32 时，我对它做了任何事情，将“cmd”添加到扩展列表中......
// Which.c:
#include <io.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
char *extensions[] = { "com", "exe", "bat", "cmd", NULL };
int is_exe(char *ext) {
int i;
for ( i = 0; extensions[i]; i++)
if ( 0 == stricmp(ext, extensions[i] ) )
return 1;
return 0;
}
int main(int argc, char **argv) {
char path[FILENAME_MAX];
char buffer[FILENAME_MAX];
char *path_var;
char *ext;
char *dir;
int i;
if (argc != 2) {
fprintf(stderr, "Usage: which <filename>\n");
return 1;
}
/* First try to find file name as-is.
*/
if ( 0 == access(argv[1], 0)) {
printf("\n%s", argv[1]);
return 0;
}
/* Okay, it wasn't found. See if it had an extension, and if not, try
* adding the usual ones...
*/
ext = strrchr(argv[1], '.' );
if ( 0 == ext++ || !is_exe(ext) ) {
for ( i = 0; extensions[i]; i++) {
sprintf(buffer, "%s.%s", argv[1], extensions[i]);
if ( 0 == access(buffer, 0)) {
printf("\n%s", buffer);
return 0;
}
}
if ( NULL == (path_var=getenv("PATH")))
return 1;
dir = strtok(path_var, ";");
do {
for ( i = 0; extensions[i]; i++) {
sprintf(buffer, "%s\%s.%s", dir, argv[1], extensions[i]);
if ( 0 == access( buffer, 0)) {
printf("\n%s", buffer);
return 0;
}
}
} while ( NULL != ( dir = strtok(NULL, ";")));
}
else {
if ( NULL == (path_var=getenv("PATH")))
return 1;
dir = strtok(path_var, ";");
do {
sprintf(buffer, "%s\%s", dir, argv[1]);
if ( 0 == access( buffer, 0)) {
printf("\n%s", buffer);
return 0;
}
} while ( NULL != ( dir = strtok(NULL, ";")));
}
return 1;
}
回答by emory
The other answers look good. For completeness, I'll add that you can also distribute the JRE with your application. It is not as elegant as the other solutions, but it will work and you won't have to worry about which version of java the client has.
其他答案看起来不错。为了完整起见，我还要补充一点，您还可以将 JRE 与您的应用程序一起分发。它不像其他解决方案那么优雅，但它可以工作，您不必担心客户端使用的是哪个版本的 java。
