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 hook
Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
@Override
public 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() {

@Override
public 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 SalmonProxy

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原文链接：
http://blog.csdn.net/poechant/article/details/6730058