1、编写native接口

package org.demo;

public class JniDemo
{
public static native int bmp2fea(byte[] bmp, byte[] fea, byte[] err);

public static native int feaMatch(byte\[\] fea1, byte\[\] fea2, String flag, int level);

}

2、根据native接口生成声明文件（.h）

javah -classpath . -jni org.demo.JniDemo

3、编写接口代码调动so动态库（.c）#include

_#include
#include
#include 'org_demo_JniDemo.h'

extern int feaMatch(char *pRegAscii, char *pVerAscii, int level);
extern int bmp2fea(unsigned char* bmp, char* feature, char* flag, char* errinfo);

JNIEXPORT jint JNICALL JAVA_org_demo_JniDemo_bmp2fea (JNIEnv *env, jclass arg, jbyteArray bmp, jbyteArray fea, jbyteArray err)
{
char out[] = { };
char errinfo[] = { };
jbyte* pbmp = (*env)->GetByteArrayElements(env, bmp, );
jsize inSize = (*env)->GetArrayLength(env, bmp);
//bmp大小平均150k,使用malloc
//char *tmp = (char*)malloc(inSize + );
//memset(tmp, , inSize+);
　　char *tmp = (char*)calloc(inSize+1, sizeOf(char));
　　if (tmp == NULL)
　　{
　　　　(*env)->ThrowNew(env,
　　　　　　(*env)->FindClass(env, "java/lang/OutOfMemoryError"), "jni calloc failed");
　　　　return;
　　}
memcpy(tmp, pbmp, inSize);

int ret = bmp2fea((unsigned char\*)tmp, (char\*)out, (char\*)errinfo);  
if (ret == )  
{  
    (\*env)->SetByteArrayRegion(env, fea, , strlen(out), (jbyte\*)out);  
    if (strlen(errinfo) > )  
         (\*env)->SetByteArrayRegion(env, err, , strlen(errinfo), (jbyte\*)out);  
}  
else  
{  
    if (strlen(errinfo) > )  
         (\*env)->SetByteArrayRegion(env, err, , strlen(errinfo), (jbyte\*)out);  
}  
if (tmp != NULL)  
{  
    free(tmp);  
}  
(\*env)->ReleaseByteArrayElements(env, bmp, pbmp, JNI\_ABORT);  
return rt;  

}

JNIEXPORT jint JNICALL Java_org_demo_JniDemo_feaMatch (JNIEnv *env, jclass arg, jbyteArray fea1, jbyteArray fea2, jstring flag, jint level)
{
char tmp1[] = { };
char tmp2[] = { };

jbyte\* pFea1 = (\*env)->GetByteArrayElements(env, fea1, );  
jsize inSize1 = (\*env)->GetArrayLength(env, fea1);  
memcpy(tmp1, pFea1, inSize1);  
jbyte\* pFea2 = (\*env)->GetByteArrayElements(env, fea2, );  
jsize inSize2 = (\*env)->GetArrayLength(env, fea2);  
memcpy(tmp2, pFea2, inSize2);  
char\* pflag = (char\*)(\*env)->GetStringUTFChars(env, flag, 0);　  
int ret = feaMatch(tmp1, tmp2, pflag, level);  
(\*env)->ReleaseByteArrayElements(env, fea1, pFea1, JNI\_ABORT);  
(\*env)->ReleaseByteArrayElements(env, fea1, pFea2, JNI\_ABORT);  
(\*env)->ReleaseStringUTFChars(env, flag, pflag);  
return ret;  

}_

4、根据.h、.c编译生成so，如下makefie文件make生成libengine.so

ODIR=.
EDIR=.
LDIR=.
INC_DIR=./

CC=g++
AR=ar -r
LD=ld
RM=rm -rf
cc=gcc
STRIP=strip
MKDIR=mkdir -p

INCLUDES=-I$(INC_DIR)
CCFLAGS=-g $(INCLUDES) -fPIC
LIBS=-lc -ldl -ldemo

SRC_DIR=./
ALL_DIR=-I$(SRC_DIR) -I/usr/java/jdk1..0_80/include/ -I/usr/java/jdk1..0_80/include/linux/

LIBAPI_SO=$(LDIR)/libengine.so
BIZD=$(EDIR)/test

PROGRAM=$(LIBAPI_SO)

####object files####
LIBAPI_OBJ=$(ODIR)/org_demo_JniDemo.o
####object files####
BIZ_OBJ=$(ODIR)/test.o
##############
all:$(PROGRAM)
force:
$(LIBAPI_SO)::$(LIBAPI_OBJ)
@echo ----Linking…----
$(LD) -share -o $(LIBAPI_SO) $(LIBAPI_OBJ) -L./ $(LIBS)
@echo ----make $@ OK----
$(BIZD)::$(BIZ_OBJ)
@echo ----Linking…----
$(cc) -o $(BIZD) $(BIZD_OBJ) -L$(LDIR) $(LIBS) $(CCFLAGS)
@echo ----make $@ OK----
clean::
@$(RM) $(ODIR)/*.o $(PROGRAM)
cleanobj::
@$(RM) $(BIZ_OBJ)
cleanbin::
@$(RM) $(PROGRAM)

.SUFFIXES:.cpp .c .o .so .a
####common#####
$(ODIR)/%.o:$(SRC_DIR)/%.c
$(cc) $(CCFLAGS) $< $(ALL_DIR) -c -o $@

5、java调用native接口

package org.demo;

import org.demo.JniDemo;

public class Demo
{
static {
// 动态库名： libdemo.so
System.loadLibrary("demo");
// libengine.so
System.loadLibrary("engine");
}

public static int bmp2fea(byte\[\] bmp, byte\[\] fea, byte\[\] err)  
{  
    return JniDemo.bmp2fea(bmp, fea, err);  
}

public static int feaMatch(byte\[\] fea1, byte\[\] fea2,String flag, int level)  
{  
     return JniDemo.feaMatch(fea1, fea2, flag, level);  
}  

}

6、配置动态库路径

方法一:
#linux用户环境变量配置：
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/demo/lib/

方法二：
#程序启动是配置JVM参数：
java -Djava.library.path=/demo/lib/ -server -cp $CLASSPATH org.demo.Test