尽管没有很好的文档记录,但就System.loadLibrary()
方法而言,java.library.path
系统属性是“只读”属性。这是一个reported bug,但它被Sun关闭,而不是被修复。问题在于JVM的ClassLoader在启动时读取一次该属性,然后将其缓存起来,不允许我们在之后以编程方式更改它。除System.getProperty()
方法调用外,行System.setProperty("java.library.path", anyVal);
将不起作用。
幸运的是,有人posted a workaround on the Sun forums。不幸的是,该链接不再有效,但我确实发现了the code on another source。这里是你可以用它来解决不能够设置java.library.path
系统属性的代码:这可能不是在所有的平台和/或JVM中工作:
public static void addDir(String s) throws IOException {
try {
// This enables the java.library.path to be modified at runtime
// From a Sun engineer at http://forums.sun.com/thread.jspa?threadID=707176
//
Field field = ClassLoader.class.getDeclaredField("usr_paths");
field.setAccessible(true);
String[] paths = (String[])field.get(null);
for (int i = 0; i < paths.length; i++) {
if (s.equals(paths[i])) {
return;
}
}
String[] tmp = new String[paths.length+1];
System.arraycopy(paths,0,tmp,0,paths.length);
tmp[paths.length] = s;
field.set(null,tmp);
System.setProperty("java.library.path", System.getProperty("java.library.path") + File.pathSeparator + s);
} catch (IllegalAccessException e) {
throw new IOException("Failed to get permissions to set library path");
} catch (NoSuchFieldException e) {
throw new IOException("Failed to get field handle to set library path");
}
}
警告。
'java.library.path'指*目录*不是*文件* – jacktrades 2015-04-02 18:15:46