利用JNA使Java访问本地C++

（1）C++代码

typedef int (*CB_OnServiceUserMessage)(uint32_t cid, uint32_t uid, const std::string& data);extern "C"{   void init(CB_OnMsg cb_OnMsg)   {      (*cb_OnMsg)();      std::cout << "Initializing..." << std::endl;   }   void start()   {      std::cout << "Start up!" << std::endl;   }   void stop()   {      std::cout << "Shut down!" << std::endl;   }   void send(char* msg)   {      std::cout << msg << std::endl;   }}

（2）Java代码

PluginProxy.java

import java.io.IOException;import java.lang.management.ManagementFactory;import com.sun.jna.Callback;import com.sun.jna.Library;import com.sun.jna.Native;public class PluginProxy{private static String libPath;    private interface LibPluginProxy extends Library{static LibPluginProxy INSTANCE = (LibPluginProxy) Native.loadLibrary(libPath, LibPluginProxy.class);public void init(Callback callback);public void start();public void stop();public void send(String msg);}public static void main(String[] args) throws Exception {libPath = "libPluginProxy.so";LibPluginProxy.INSTANCE.init(new CB_OnMsg());System.out.println("in main function.");//add shutdown hookRuntime.getRuntime().addShutdownHook(new Thread(new Runnable() {@Overridepublic void run() {Native.unregister(LibPluginProxy.class);System.out.println("stop..");LibPluginProxy.INSTANCE.stop();String n = ManagementFactory.getRuntimeMXBean().getName();if (n == null) return;String pid = n.substring(0, n.indexOf("@"));if (pid == null) return;try{Runtime.getRuntime().exec("kill -9 " + pid);}catch (IOException e){e.printStackTrace();}System.exit(-1);}}));Thread t = new Thread(new Runnable() {@Overridepublic void run() {LibPluginProxy.INSTANCE.start();System.out.println("started in thread..");}});t.start();System.out.println("started!!");}}

CB_OnMsg.java

import com.sun.jna.Callback;public class CB_OnMsg implements Callback {// 应用创建public final int onMsg() {System.out.println("CB_OnMsg, in function onMsg.");return 0;}}

（3）编译C++的.so共享库

编写makefile，细节忽略，只提供最主要的command，如下：

g++ -shared -o libplugin.so -fPIC -Wall -ggdb -D_REENTRANT -DHAVE_EPOLL -DXML_NULL -DSTATUS_NEWPROTOCOL -Wl,-rpath,../bin#注：此段有多余的flags，有待修改...

（4）生成Java的JAR包

在eclipse中生成JAR包，linux生成JAR命令请Google......

（5）运行JAR包调用.so共享库

在linux下输入命令：

java -cp jna-3.3.0.jar:ss.jar PluginProxy