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[Java教程]JNA 如何 加载多个 存在依赖的 DLL 库


JNA 的出现,极大的简化了原有的 JNI 技术。下面是JNA github地址:https://github.com/java-native-access/jna

1. 简单的一个例子

/** Simple example of JNA interface mapping and usage. */public class HelloWorld {  public interface CLibrary extends Library {    CLibrary INSTANCE = (CLibrary)Native.loadLibrary((Platform.isWindows() ? "msvcrt" : "c"), CLibrary.class);        void printf(String format, Object... args);	// void printf(const char *format, [argument]);      }  public static void main(String[] args) {    CLibrary.INSTANCE.printf("Hello, World\n");    for (int i=0; i < args.length; i++) {      CLibrary.INSTANCE.printf("Argument %d: %s\n", i, args[i]);    }  }  }

原理是,通过 CLibrary extends Libarary 在其中加载系统的 DLL/so 库,并列出Java要调用的DLL库函数,该函数到DLL库函数直接的映射有JNA来完成。

这样就可以调用DLL/so库中的函数了。

2. 如何使用 JNA 加载多个DLL库,而且它们之间存在依赖关系

http://stackoverflow.com/questions/32609829/load-multiple-libraries-with-jna

Is there a way in JNA to load multiple libraries with Java?

I usually use Native.loadLibrary(...) to load one DLL. But I guess its not working this way because I assign this function call to the instance member.

Let's say I have library foo and library barbar has a dependency on foo; it also has a dependency on baz, which we are not mapping with JNA:

public class Foo {  public static final boolean LOADED;  static {    Native.register("foo");    LOADED = true;  }  public static native void call_foo();}public class Bar {  static {    // Reference "Foo" so that it is loaded first    if (Foo.LOADED) {      System.loadLibrary("baz");      // Or System.load("/path/to/libbaz.so")      Native.register("bar");    }  }  public static native void call_bar();}

The call to System.load/loadLibrary will only be necessary if baz is neither on your library load path (PATH/LD_LIBRARY_PATH, for windows/linux respectively) nor in the same directory as bar(windows only).

EDIT

You can also do this via interface mapping:

public interface Foo extends Library {  Foo INSTANCE = (Foo)Native.loadLibrary("foo");}public interface Bar extends Library {  // Reference Foo prior to instantiating Bar, just be sure  // to reference the Foo class prior to creating the Bar instance  Foo FOO = Foo.INSTANCE;  Bar INSTANCE = (Bar)Native.loadLibrary("bar");}

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3. 自己的代码例子:

public class DDLTest {	public static void main(String[] args){		System.out.println(System.getProperty("java.library.path"));		FingerLibrary.Fingerdll.ZAZCloseDeviceEx(-1);				int r = ID_FprCap.fprCap.LIVESCAN_Init();		ID_FprCap.fprCap.LIVESCAN_Close();		ID_FprCap.fprCap.LIVESCAN_BeginCapture(1);		ID_FprCap.fprCap.LIVESCAN_GetFPRawData(1, "aaaaaa");		r = ID_Fpr.INSTANCE.FP_FeatureMatch("aaaaaaaaaaa", "aaaaaaaaaaa", (float)0.5);	}			public interface FingerLibrary extends Library {		 int FPDATASIZE = 256;		 int IMGWIDTH = 256;		 int IMGHEIGHT = 288;		 int IMGSIZE = 73728;				 // 窗口消息		 int WM_FPMESSAGE = 1024 + 120; // 自定义消息		 int FPM_DEVICE = 0x01; // 状态提示		 int FPM_PLACE = 0x02; // 请按手指		 int FPM_LIFT = 0x03; // 请抬起手指		 int FPM_CAPTURE = 0x04; // 采集图像		 int FPM_ENROLL = 0x06; // 登记指纹模版		 int FPM_GENCHAR = 0x05; // 采集特征点		 int FPM_NEWIMAGE = 0x07; // 指纹图像		 int RET_OK = 0x1;		 int RET_FAIL = 0x0;				 FingerLibrary Fingerdll = (FingerLibrary) Native.loadLibrary("ZAZAPIt", FingerLibrary.class);				 public int ZAZOpenDeviceEx(int[] hHandle, int nDeviceType, int iCom, int iBaud, int nPackageSize, int iDevNum);		 public int ZAZCloseDeviceEx(int handle);		 public int ZAZVfyPwd(int pHandle, int nAddr,  byte[] pPassword);		 public int ZAZReadInfPage(int pHandle, int nAddr, byte[] pInf);	   public int ZAZReadIndexTable(int pHandle, int nAddr, int nPage, byte[] UserContent); 	   //	   public int FP_FeatureMatch(String pFeatureData1, String pFeatureData2, float pfSimilarity);	}				public interface ID_Fpr extends Library {		ID_Fpr INSTANCE = (ID_Fpr)Native.loadLibrary("ID_Fpr", ID_Fpr.class);//		public int LIVESCAN_Init();		public int FP_FeatureMatch(String pFeatureData1, String pFeatureData2, float pfSimilarity);		//int __stdcall FP_FeatureMatch(unsigned char * pFeatureData1,	//输入参数 指纹特征数据1		//		 						unsigned char * pFeatureData2,	//输入参数 指纹特征数据2		//		 						float * pfSimilarity);			//输出参数 匹配相似度值0.00-1.00		//		typedef int (__stdcall *FP_FeatureMatch)(unsigned char * pFeatureData1,	//输入参数 指纹特征数据1//			 	 unsigned char * pFeatureData2,	//输入参数 指纹特征数据2//				 float * pfSimilarity);			//输出参数 匹配相似度值0.00-1.00	}		public interface ID_FprCap extends StdCallLibrary {	  ID_Fpr fpr = ID_Fpr.INSTANCE ;	  ID_FprCap fprCap = (ID_FprCap)Native.loadLibrary("ID_FprCap", ID_FprCap.class);	  	  public int LIVESCAN_Init();		//int __stdcall LIVESCAN_Init();	  public int LIVESCAN_Close();	//int __stdcall	LIVESCAN_Close();	  public int LIVESCAN_BeginCapture(int nChannel);	  public int LIVESCAN_GetFPRawData(int nChannel, String pRawData);//	  int		__stdcall	LIVESCAN_BeginCapture(	int nChannel );//	  int		__stdcall	LIVESCAN_GetFPRawData(int nChannel,unsigned char *pRawData);	  	  public int LIVESCAN_GetFPBmpData(int nChannel, String pBmpData);//	  int		__stdcall	LIVESCAN_GetFPBmpData(int nChannel, unsigned char *pBmpData);	  public int LIVESCAN_EndCapture(int nChannel);//	  int		__stdcall	LIVESCAN_EndCapture(int nChannel );	  public int LIVESCAN_IsSupportSetup();	  //	  int		__stdcall	LIVESCAN_IsSupportSetup();	  public int LIVESCAN_GetVersion();//	  int		__stdcall	LIVESCAN_GetVersion();	  public int LIVESCAN_GetDesc(String pszDesc);//	  int		__stdcall	LIVESCAN_GetDesc(char pszDesc[1024]);	  public int LIVESCAN_GetErrorInfo(int nErrorNo, String pszErrorInfo);//	  int		__stdcall	LIVESCAN_GetErrorInfo(int nErrorNo, char pszErrorInfo[256]);	  	}		}