Is it possible to add a new path for native libraries at runtime ?.
(Instead of starting Java with the property java.library.path), so a call to System.loadLibrary(nativeLibraryName)
will include that path when trying to find nativeLibraryName
.
Is that possible or these paths are frozen once the JVM has started ?
Go to Project properties->Java Build Path->Source. You'll find a list of source-folders. Each entry under the the Source tab has Native library locations. It supports paths within the workspace and it will make Eclipse add it to your java.
Native libraries are platform-specific library files, including . dll, . so, or *SRVPGM objects, that can be configured within shared libraries. Native libraries are visible to an application class loader whenever the shared library is associated with an application.
(still within the Project Properties dialog) Click on the "Run/Debug Settings", select your Java class, then click on the "Edit..." button. Select the "Arguments" tab, then add -Djava. library. path="C:\chilkatJava;${env_var:PATH}" where "C:\chilkatJava" is the directory path containing the "chilkat.
[This solution don't work with Java 10+]
It seems impossible without little hacking (i.e. accessing private fields of the ClassLoader class)
This blog provide 2 ways of doing it.
For the record, here is the short version.
Option 1: fully replace java.library.path with the new value)
public static void setLibraryPath(String path) throws Exception {
System.setProperty("java.library.path", path);
//set sys_paths to null so that java.library.path will be reevalueted next time it is needed
final Field sysPathsField = ClassLoader.class.getDeclaredField("sys_paths");
sysPathsField.setAccessible(true);
sysPathsField.set(null, null);
}
Option 2: add a new path to the current java.library.path
/**
* Adds the specified path to the java library path
*
* @param pathToAdd the path to add
* @throws Exception
*/
public static void addLibraryPath(String pathToAdd) throws Exception{
final Field usrPathsField = ClassLoader.class.getDeclaredField("usr_paths");
usrPathsField.setAccessible(true);
//get array of paths
final String[] paths = (String[])usrPathsField.get(null);
//check if the path to add is already present
for(String path : paths) {
if(path.equals(pathToAdd)) {
return;
}
}
//add the new path
final String[] newPaths = Arrays.copyOf(paths, paths.length + 1);
newPaths[newPaths.length-1] = pathToAdd;
usrPathsField.set(null, newPaths);
}
I used this in Java 12/13 which should work for any JVM with MethodHandles:
Lookup cl = MethodHandles.privateLookupIn(ClassLoader.class, MethodHandles.lookup());
VarHandle sys_paths = cl.findStaticVarHandle(ClassLoader.class, "sys_paths", String[].class);
sys_paths.set(null);
It has the benefit of being a Java API.
It is replaces the:
final Field sysPathsField = ClassLoader.class.getDeclaredField("sys_paths");
sysPathsField.setAccessible(true);
sysPathsField.set(null, null);
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With