可以将native方法比作Java程序同Ｃ程序的接口，其实现步骤为：
1、编写java源程序，add用native修饰

package p2019.p06;public class NativeAdd { public native int add(int a,int b);}

2、编译java程序，生成NativeAdd.class文件
[root@localhost java]# javac p2019/p06/NativeAdd.java
生成NativeAdd.class NativeAdd.java
3、javah生成.h文件
[root@localhost java]# javah p2019.p06.NativeAdd
生成p2019_p06_NativeAdd.h

1 /* DO NOT EDIT THIS FILE - it is machine generated */ 2 #include <jni.h> 3 /* Header for class p2019_p06_NativeAdd */ 4 5 #ifndef _Included_p2019_p06_NativeAdd 6 #define _Included_p2019_p06_NativeAdd 7 #ifdef __cplusplus 8 extern "C" { 9 #endif 10 /* 11 * Class: p2019_p06_NativeAdd 12 * Method: add 13 * Signature: (II)I 14 */ 15 JNIEXPORT jint JNICALL Java_p2019_p06_NativeAdd_add 16 (JNIEnv *, jobject, jint, jint); 17 18 #ifdef __cplusplus 19 } 20 #endif 21 #endif

4、将生成的.h文件拷贝到/usr/java/jdk1.8.0_181-amd64/include/和/usr/java/jdk1.8.0_181-amd64/include/llinux目录下，编译C程序时用
5、编写C程序NativeAdd.c

1 #include <stdio.h> 2 #include "p2019_p06_NativeAdd.h" 3 JNIEXPORT jint JNICALL Java_p2019_p06_NativeAdd_add(JNIEnv * _env, jobject _obj, jint _a, jint _b) 4 { 5 return _a+_b; 6 }

6、编译C程序，生成.so文件
gcc -I /usr/java/jdk1.8.0_181-amd64/include/ -I /usr/java/jdk1.8.0_181-amd64/include/linux/ NativeAdd.c -fPIC -shared -LD -o NativeAdd.so
7、编写java测试程序，调用NativeAdd.so

package p2019.p06;public class NativeAddTest { public static void main(String[] args){ System.out.println(System.getProperty("java.library.path"));// System.loadLibrary("NativeAdd");这个方法找不到NativeAdd.so System.load("/usr/lib/NativeAdd.so"); NativeAdd nativeAdd = new NativeAdd(); System.out.println(nativeAdd.add(1,2)); }}

显示结果 3