dll的Java调用功能 [英] Java call function from a dll

问题描述

我有这个python脚本，可以导入 zkemkeeper dll并连接到考勤设备（ ZKTeco ）。这是我正在使用的脚本：

I have this python script that imports a zkemkeeper dll and connects to a time attendance device(ZKTeco). Here is is a script I'm using:

from win32com.client import Dispatch

zk = Dispatch("zkemkeeper.ZKEM")
zk.Connect_Net("192.168.0.17", 4370)
print(zk.StartIdentify())
print(zk.StartEnrollEx(7, 2, 1))

这可以正常工作。但是我想使用java实现相同的目的。如何调用 Connect_Net 方法？
我在Java中尝试了以下操作，但没有起作用：

This works fine as expected. However I want to achieve the same using java. How can I call that Connect_Net method? I tried the following in java but didn't work:

public class ZKEM {

    static {
        System.loadLibrary("zkemkeeper");
    }

    ZKEM() {
    }

    public static native boolean Connect_Net(String IPAdd, int Portl);

}

public class Main {

    public static void main(String[] args) {

        System.err.println(ZKEM.Connect_Net("192.168.0.17", 4370));
    }

}

推荐答案

从Java调用本机代码的两个选择是 JNI（Java本机接口）和 JNA（Java本机访问）

The two choices for calling native code from Java are JNI (Java Native Interface) and JNA (Java Native Access)

Java运行时可以开箱即用地执行JNI，但是您需要创建一个包装库，其中包含专门为JNI设计的功能（只需放入 native 关键字是不够的。）

The Java runtime can do JNI out of the box, but you need to create a wrapper library with functions specifically made for JNI (just putting in a native keyword is not enough).

JNA是使用 libffi 以便可以从Java访问本机代码。

JNA is a 3rd party library that uses libffi to make native code accessible from Java.

您必须亲自了解哪种方法更好满足您的需求。

You have to see for yourself which approach better suits your needs.

编辑：再次查看示例代码，这是COM调用吗？虽然可以使用JNA来完成COM（自己动手做），但它相当复杂。最好的选择可能是包装C库，它可以进行实际的调用或Java / COM桥产品，例如 JACOB （不过，从未使用过）。

looking at your example code again, is that a COM call? While COM can be done with JNA (doing that myself), it's quite complicated. Your best bet is probably a wrapper C library that does the actual calls or a Java/COM bridge product like JACOB (have never used it, however).

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