加载DLL出错。

[66i88]

package com.aaa;

public class DD {
    public static void add()
    {
    	return;
    }
    
	static {
		loadNativeLib();
	}

	private static void loadNativeLib(){
		try {
			System.loadLibrary("user32.dll");			
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

package com.aaa;

public class Hello {
	public static void main(String[] args){
	    System.out.println("WOW!!");
	    DD.add();
	    System.out.println("WOW22!!");
	}
}

WOW!!
Exception in thread "main" java.lang.UnsatisfiedLinkError: no user32.dll in java.library.path
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at com.aaa.DD.loadNativeLib(DD.java:15)
at com.aaa.DD.<clinit>(DD.java:10)
at com.aaa.Hello.main(Hello.java:6)

什么原因，缺少文件吗？
谢谢