在Java中运行时为本机库添加新路径

Question

是否有可能在运行时为本机库添加新路径？。（而不是使用Java.library.path属性启动Java），因此在尝试查找nativeLibraryName时，调用system.loadlibrary(nativeLibraryName)将包含该路径。这是可能的，还是一旦JVM启动，这些路径就被冻结了？

Answer 1

[此解决方案不适用于Java10+]

如果没有很少的黑客攻击（即访问ClassLoader类的私有字段），这似乎是不可能的

这个博客提供了两种方法。

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);
}

/**
* 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);
}