【实例】java调用dll的文档搜了不少，发现都不完整，或者说的不够详细，这里通过自己的实际操作，并将过程做了整理，通过实例说明java如何用jacob调用dll里的函数。
由于某系统加密需要，需要实现从dll里实现某些功能（比如获取当前CPU序列号），并在Java中调用该函数。
（一）准备工作：需要用到文件有：jacob.dll和jacob.jar分别放到jdk/bin下和class_path下。文件下载地址：
（二）建立一个VB的Activex Dll 工程，命名为名为getCPU，自动生成Class1文件（工程名字和类名建议用英文名，以防调用时编码出问题），并添加代码如下：
Private Type OSVERSIONINFO
dwOSVersionInfoSize As Long
dwMajorVersion As Long
dwMinorVersion As Long
dwBuildNumber As Long
dwPlatformId As Long
szCSDVersion As String * 128 ' Maintenance string for PSS usage
End Type
Private Declare Function GetVersionEx Lib "kernel32" Alias "GetVersionExA" (lpVersionInformation As OSVERSIONINFO) As Long
Private Declare Function GetComputerName Lib "kernel32" Alias "GetComputerNameA" (ByVal lpBuffer As String, nSize As Long) As Long
Public Function GetCPUid(para As String) As String
On Error GoTo doError
Dim len5 As Long, aa As Long
Dim cmprName As String
Dim Computer As String
Dim CPUs As Object, MyCpu As Object
Dim osver As OSVERSIONINFO
Dim SerialNo As String
'取得Computer Name
cmprName = String(255, 0)
len5 = 256
aa = GetComputerName(cmprName, len5)
cmprName = Left(cmprName, InStr(1, cmprName, Chr(0)) - 1)
Computer = cmprName '取得CPU端口号
Set CPUs = GetObject("winmgmts:{impersonationLevel=impersonate}!\\" & Computer & "\root\cimv2").ExecQuery("select * from Win32_Processor")
For Each MyCpu In CPUs
SerialNo = MyCpu.ProcessorId
Exit For
Next
GetCPUid = SerialNo
Exit Function
doError:
GetCPUid = ""
End Function
保存后编译为getCPU.dll 并复制到Windows/System32下。
（三）将dll导入为com组件
运行命令：regsvr32 C:\windows\system32\getCPU.dll 显示成功导入。
（四）建立测试Java文件，内容如下：
package test;
import com.jacob.activeX.ActiveXComponent;
import com.jacob.com.*;
public class CallDll 
{
public static void main(String args[]) {
ActiveXComponent app = new ActiveXComponent("getCPU.Class1");
Dispatch mycom = (Dispatch) app.getObject();
if(mycom!=null){
Variant result = Dispatch.callN(mycom, "GetCPUid", new String[]{""});
System.out.print(result);
}
}
}