如何在Java程序中的DLL中调用方法 [英] How to call a method in DLL in a Java program

问题描述

我试图使用JNA在DLL中调用一个方法。到目前为止，使用

  Runtime.getRuntime（）加载DLL（myworkspace / test.dll）; 
  

这个dll包含一个我需要访问的方法。如何在Java文件中执行DLL中存在的方法。我创建一个对象或DLL的东西，然后在点运算符之后获取方法名称。

解决方案

从源：

  package jnahelloworldtest; 
 
 import com.sun.jna.Library; 
 import com.sun.jna.Native; 
 import com.sun.jna.NativeLong; 
 import com.sun.jna.Platform; 
 import com.sun.jna。*; 
 
 / **本机库声明和使用的简单示例。 * / 
 public class Main {
 public interface simpleDLL extends Library {
 simpleDLL INSTANCE =（simpleDLL）Native.loadLibrary（
（Platform.isWindows（）？simpleDLL simpleDLLLinuxPort），simpleDLL.class）; 
 //可以检查运行哪个程序的平台，例如，我们假设库中有一个linux端口（它不附加到可下载项目）
 byte giveVoidPtrGetChar（指针参数）; // char giveVoidPtrGetChar（void * param）; 
 int giveVoidPtrGetInt（指针参数）; // int giveVoidPtrGetInt（void * param）; 
 int giveIntGetInt（int a）; // int giveIntGetInt（int a）; 
 void simpleCall（）; // void simpleCall（）; 
} 
 
 public static void main（String [] args）{
 
 simpleDLL sdll = simpleDLL.INSTANCE; 
 
 sdll.simpleCall（）; //调用void函数
 
 int a = 3; 
 int result1 = sdll.giveIntGetInt（a）; //调用函数int参数& result 
 System.out.println（giveIntGetInt（+ a +）：+ result1）; 
 
 String testStr =ToBeOrNotToBe; 
内存mTest =新内存（testStr.length（）+ 1）; //'+1'记住\0字符的额外字节！ 
 mTest.setString（0，testStr）; 
 String testReturn = mTest.getString（0）; //您可以看到String已正确存储在Memory对象中
 System.out.println（Memory in Memory：+ testReturn）; 
 
内存intMem =新内存（4）; //分配空间
 intMem.setInt（0，666）; //将分配的内存设置为一个整数
指针intPointer = intMem.getPointer（0）; 
 
 int int1 = sdll.giveVoidPtrGetInt（Pointer.NULL）; //传递null，获取默认结果
 System.out.println（giveVoidPtrGetInt（null）：+ int1）; //传递存储在内存对象中的int，使其返回
 int int2 = sdll.giveVoidPtrGetInt（intMem）; 
 // int int2 = sdll.giveVoidPtrGetInt（intPointer）;导致JVM崩溃，直接使用内存对象！ 
 System.out.println（giveVoidPtrGetInt（666）：+ int2）; 
 
字节char1 = sdll.giveVoidPtrGetChar（Pointer.NULL）; //传递null，获取默认结果
字节char2 = sdll.giveVoidPtrGetChar（mTest）; //传递存储在Memory对象中的字符串，获取第一个字母
 
 System.out.println（giveVoidPtrGetChar（null）：+（char）char1）; 
 System.out.println（giveVoidPtrGetChar（'ToBeOrNotToBe'）：+（char）char2）; 
 
} 
} 
  

I am trying to call a method in a DLL using JNA. So far have loaded the DLL using

Runtime.getRuntime().load("myworkspace/test.dll");

This dll contaings a method that I need to access. How can I execute the method present in DLL in my Java file. Do I create an object or something of the DLL and then get the method name after the dot operator.

解决方案

From the source:

package jnahelloworldtest;

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.NativeLong;
import com.sun.jna.Platform;
import com.sun.jna.*;

/** Simple example of native library declaration and usage. */
public class Main {
    public interface simpleDLL extends Library {
        simpleDLL INSTANCE = (simpleDLL) Native.loadLibrary(
            (Platform.isWindows() ? "simpleDLL" : "simpleDLLLinuxPort"), simpleDLL.class);
        // it's possible to check the platform on which program runs, for example purposes we assume that there's a linux port of the library (it's not attached to the downloadable project)
        byte giveVoidPtrGetChar(Pointer param); // char giveVoidPtrGetChar(void* param);
        int giveVoidPtrGetInt(Pointer param);   //int giveVoidPtrGetInt(void* param);
        int giveIntGetInt(int a);               // int giveIntGetInt(int a);
        void simpleCall();                      // void simpleCall();
    }

    public static void main(String[] args) {

        simpleDLL sdll = simpleDLL.INSTANCE;

        sdll.simpleCall();  // call of void function

        int a = 3;
        int result1 = sdll.giveIntGetInt(a);  // calling function with int parameter&result
        System.out.println("giveIntGetInt("+a+"): " + result1);

        String testStr = "ToBeOrNotToBe";
        Memory mTest = new Memory(testStr.length()+1);  // '+1' remember about extra byte for \0 character!
        mTest.setString(0, testStr);
        String testReturn = mTest.getString(0); // you can see that String got properly stored in Memory object
        System.out.println("String in Memory:"+testReturn);

        Memory intMem = new Memory(4);  // allocating space
        intMem.setInt(0, 666); // setting allocated memory to an integer
        Pointer intPointer = intMem.getPointer(0);

        int int1 = sdll.giveVoidPtrGetInt(Pointer.NULL); // passing null, getting default result
        System.out.println("giveVoidPtrGetInt(null):" + int1); // passing int stored in Memory object, getting it back
        int int2 = sdll.giveVoidPtrGetInt(intMem);
       //int int2 = sdll.giveVoidPtrGetInt(intPointer);  causes JVM crash, use memory object directly!
        System.out.println("giveVoidPtrGetInt(666):" + int2);

        byte char1 = sdll.giveVoidPtrGetChar(Pointer.NULL);  // passing null, getting default result
        byte char2 = sdll.giveVoidPtrGetChar(mTest);        // passing string stored in Memory object, getting first letter

        System.out.println("giveVoidPtrGetChar(null):" + (char)char1);
        System.out.println("giveVoidPtrGetChar('ToBeOrNotToBe'):" + (char)char2);

    }
}

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