java 如何在java中访问C++库（DLL）的方法
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how to access a method of C++ library (DLL) in java
提问by sabith
I have one c++ dll file. And I know the methods used in it. I need to call these methods from my java code. I don't have access to modify the DLL file. Please provide me a solution to do this.
我有一个 C++ dll 文件。我知道其中使用的方法。我需要从我的 java 代码中调用这些方法。我无权修改 DLL 文件。请为我提供一个解决方案来做到这一点。
回答by Samuel Audet
I created JavaCPPexactly for that purpose. I'll copy/paste some sample code and explanations from the page:
我正是为此目的创建了JavaCPP。我将从页面复制/粘贴一些示例代码和解释：
The most common use case involves accessing some legacy library written for C++, for example, inside a file named LegacyLibrary.h containing this C++ class:
最常见的用例涉及访问一些为 C++ 编写的遗留库，例如，在包含此 C++ 类的名为 LegacyLibrary.h 的文件中：
#include <string>
namespace LegacyLibrary {
class LegacyClass {
public:
const std::string& get_property() { return property; }
void set_property(const std::string& property) { this->property = property; }
std::string property;
};
}
To get the job done with JavaCPP, we can easily define a Java class such as this one--although one could use the Parser to produce it from the header file as demonstrated below:
为了使用 JavaCPP 完成工作，我们可以轻松定义这样的 Java 类——尽管可以使用解析器从头文件中生成它，如下所示：
import com.googlecode.javacpp.*;
import com.googlecode.javacpp.annotation.*;
@Platform(include="LegacyLibrary.h")
@Namespace("LegacyLibrary")
public class LegacyLibrary {
public static class LegacyClass extends Pointer {
static { Loader.load(); }
public LegacyClass() { allocate(); }
private native void allocate();
// to call the getter and setter functions
public native @StdString String get_property(); public native void set_property(String property);
// to access the member variable directly
public native @StdString String property(); public native void property(String property);
}
public static void main(String[] args) {
// Pointer objects allocated in Java get deallocated once they become unreachable,
// but C++ destructors can still be called in a timely fashion with Pointer.deallocate()
LegacyClass l = new LegacyClass();
l.set_property("Hello World!");
System.out.println(l.property());
}
}
Alternately, we can produce a Java interface by parsing the header file with a config class such as this one:
或者，我们可以通过使用配置类解析头文件来生成 Java 接口，例如：
@Properties(target="LegacyLibrary", value=@Platform(include="LegacyLibrary.h"))
public class LegacyLibraryConfig implements Parser.InfoMapper {
public void map(Parser.InfoMap infoMap) {
}
}
And the following build commands:
以及以下构建命令：
$ javac -cp javacpp.jar LegacyLibraryConfig.java
$ java -jar javacpp.jar LegacyLibraryConfig
$ javac -cp javacpp.jar LegacyLibrary.java
$ java -jar javacpp.jar LegacyLibrary
For more complex examples including Maven/IDE integration, check out the JavaCPP Presets!
对于包括 Maven/IDE 集成在内的更复杂的示例，请查看JavaCPP 预设！
