java中调用dll动态库的简洁方法JNative

Java中调用DLL方法，是通过JNI接口实现的，http://www.ibm.com/developerworks/cn/java/l-linux-jni/ 这里有详细的说明。大概是先用Java写一个接口类，然后用javah 生成一个xxx.h的c语言的头文件，然后用C实现这个头文件，在这个实现接口中调用其他已经实现的接口。

解压JNative-1.3.2.zip 获得三个文件，分别是：JNativeCpp.dll，libJNativeCpp.so，JNative.jar 。JNativeCpp.dll Windows下用的，拷到windows / system32目录下；
libJNativeCpp.so Linux下使用的；
JNative.jar　这是一个扩展包，加载到你的程序中就可以。

一个简单例子

import org.xvolks.jnative.JNative;
import org.xvolks.jnative.Type;
import org.xvolks.jnative.exceptions.NativeException;

public class JNativeTest {
   
    public static final int messageBox(int parentHandle, String message,
             String caption, int buttons){// throws NativeException, IllegalAccessException {
          JNative n = null;
          try {
             n = new JNative("User32.dll", "MessageBoxA"); //“.dll”不用也可以， 常量DLL_NAME的值为User32.dll
             // 构造JNative时完成装载User32.dll,并且定位MessageBoxA方法
             n.setRetVal(Type.INT); // 指定返回参数的类型
             int i = 0;
             n.setParameter(i++, Type.INT, "" + parentHandle);
             n.setParameter(i++, Type.STRING, message);
             n.setParameter(i++, Type.STRING, caption);
             n.setParameter(i++, Type.INT, "" + buttons); // 指定位置上的参数类型和值
             n.invoke(); // 调用方法
             return Integer.parseInt(n.getRetVal());
          }
          catch(Exception ex){
           ex.printStackTrace();
          }
          finally {
          
             if (n != null)
     try {
      n.dispose();
     } catch (NativeException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
     } catch (IllegalAccessException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
     } // 记得释放
          }
          return 0;
       }
    public static void main(String[] args) throws NativeException, IllegalAccessException{
        JNativeTest.messageBox(100,"这是使用jnative练习", "jnativetest", 1);
    }
}

关于linux下编译 C代码部分说明：

对于linux不同版本，可能会导致libJNativeCpp.so不同
原带的libJNativeCpp.so 是在glic2.4下编译的
为了适应glic2.3的情况，重新编译了libJNativeCpp.so，在for gcc3.4.6 glibc 2.3下。
编译办法：
   在JNative-1.3.2-src\JNativeCpp\Release目录下
   1、备份calls.o和 asm_io.o这两个Object文件
   2、make clean
   3、恢复到当前目录calls.o和 asm_io.o这两个Object文件
   4、make
  
   目前已经修改了Release目录下的makefile和subdir.mk文件，使得在make clean的时候不删除calls.o和 asm_io.o两个文件
  
附：linux 动态库搜索路径：
export LD_LIBRARY_PATH=`pwd`:$LD_LIBRARY_PATH

makefile 文件

################################################################################
# Automatically-generated file. Do not edit!
################################################################################

-include ../makefile.init

RM := rm -rf

# All of the sources participating in the build are defined here
-include sources.mk
-include subdir.mk
-include objects.mk

ifneq ($(MAKECMDGOALS),clean)
ifneq ($(strip $(C++_DEPS)),)
-include $(C++_DEPS)
endif
ifneq ($(strip $(CC_DEPS)),)
-include $(CC_DEPS)
endif
ifneq ($(strip $(C_DEPS)),)
-include $(C_DEPS)
endif
ifneq ($(strip $(CPP_DEPS)),)
-include $(CPP_DEPS)
endif
ifneq ($(strip $(CXX_DEPS)),)
-include $(CXX_DEPS)
endif
ifneq ($(strip $(C_UPPER_DEPS)),)
-include $(C_UPPER_DEPS)
endif
endif

-include ../makefile.defs

# Add inputs and outputs from these tool invocations to the build variables

# All Target
all: libJNativeCpp.so

# Tool invocations
libJNativeCpp.so: $(OBJS) $(OBJS_ASM) $(USER_OBJS)
    @echo ''Building target: $@''
    @echo ''Invoking: GCC C++ Linker''
    g++ -shared -o"libJNativeCpp.so" $(OBJS) $(OBJS_ASM) $(USER_OBJS) $(LIBS)
    @echo ''Finished building target: $@''
    @echo '' ''

# Other Targets
clean:
    -$(RM) $(OBJS)$(C++_DEPS)$(CC_DEPS)$(C_DEPS)$(CPP_DEPS)$(LIBRARIES)$(CXX_DEPS)$(C_UPPER_DEPS) libJNativeCpp.so
    -@echo '' ''

.PHONY: all clean dependents
.SECONDARY:

-include ../makefile.targets

subdir.mk 文件

################################################################################
# Automatically-generated file. Do not edit!
################################################################################

# Add inputs and outputs from these tool invocations to the build variables
C_SRCS +=
../jni_util.c
../mem.c

CPP_SRCS +=
../CallBack.cpp
../WindowProcUtil.cpp
../org_xvolks_jnative_JNative.cpp

ASM_SRCS +=
../asm_io.asm
../calls.asm

OBJS +=
./CallBack.o
./WindowProcUtil.o
./jni_util.o
./mem.o
./org_xvolks_jnative_JNative.o

OBJS_ASM +=
./asm_io.o
./calls.o

C_DEPS +=
./jni_util.d
./mem.d

CPP_DEPS +=
./CallBack.d
./WindowProcUtil.d
./org_xvolks_jnative_JNative.d

# Each subdirectory must supply rules for building sources it contributes
%.o: ../%.cpp
    @echo ''Building file: $<''
    @echo ''Invoking: GCC C++ Compiler''
    g++ -I"/home/gongjan/jdk1.5.0_08/include/" -I"/home/gongjan/jdk1.5.0_08/include/linux" -O3 -Wall -c -fmessage-length=0 -Wl,--add-stdcall-alias -MMD -MP -MF"$(@:%.o=%.d)" -MT"$(@:%.o=%.d)" -o"$@" "$<"
    @echo ''Finished building: $<''
    @echo '' ''

%.o: ../%.asm
    @echo ''Building file: $<''
    @echo ''Invoking: GCC Assembler''
    nasm -f elf -d ELF_TYPE -o"$@" "$<"
    @echo ''Finished building: $<''
    @echo '' ''

%.o: ../%.c
    @echo ''Building file: $<''
    @echo ''Invoking: GCC C Compiler''
    gcc -I"/home/gongjan/jdk1.5.0_08/include/linux" -I"/home/gongjan/jdk1.5.0_08/include/" -O3 -Wall -c -fmessage-length=0 -Wl,--add-stdcall-alias -MMD -MP -MF"$(@:%.o=%.d)" -MT"$(@:%.o=%.d)" -o"$@" "$<"
    @echo ''Finished building: $<''
    @echo '' ''
文章出处：http://www.diybl.com/course/3_program/java/javajs/2008520/117063.html