JNA调用lazarus写的共享库，实现字节输出传出功能

注意：
linuxua下JNA/JNI调用lazarus0.9.x编译的共享库，会造成JVM的崩溃，慎用！也许更高版本的lazarus会更正这个问题，不管怎样，使用之前要做充分的测试。

lazarus代码

procedure hello2(const name : PChar; var bytAry : TByteArray; var len : Integer); stdcall;
var
   s : AnsiString;
begin
  s := format('hello %s', [strpas(name)]);
  len := length(s);
  s := s + '                           ';
  TByteArrayUtils.copy(@bytAry, @s[1], length(s));
end;

linux下编译后的文件名是libdemo.so
windows下编译后的文件名是libdemo.dll

对应java类声明

    public interface DllLib extends Library{
        DllLib instance = (DllLib)Native.loadLibrary("asmtux",DllLib.class);
        void hello(String name, int age);
        void hello1(String name, String[] strs);
        void hello2(String name, ByteBuffer bytArray, IntByReference len);
      }

调用代码

        ByteBuffer buffer = ByteBuffer.allocate(255);
        IntByReference lenRef = new IntByReference();
        DllLib.instance.hello2("jim", buffer, lenRef);
        int len = lenRef.getValue();
        byte[] byTemp = new byte[255];
        buffer.get(byTemp, 0, len);
        System.out.println(new String(byTemp, 0, len))

最后界面上输出 hello jim，
此代码在tomcat上运行成功

附上servlet代码
package com.asm.app;

import java.io.IOException;
import java.io.PrintWriter;
import java.nio.ByteBuffer;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.ptr.IntByReference;

@WebServlet(urlPatterns="/jna")
public class JNADemo extends HttpServlet {
    public interface DllLib extends Library{
        DllLib instance = (DllLib)Native.loadLibrary("demo",DllLib.class);
        void hello2(String name, ByteBuffer bytArray, IntByReference len);
      }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        PrintWriter out = resp.getWriter();
        resp.setContentType("text/html");
        resp.setCharacterEncoding("utf-8");
        ByteBuffer buffer = ByteBuffer.allocate(255);
        IntByReference lenRef = new IntByReference();
        DllLib.instance.hello2("jim", buffer, lenRef);
        int len = lenRef.getValue();
        byte[] byTemp = new byte[255];
        buffer.get(byTemp, 0, len);
        out.println(new String(byTemp, 0, len));
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }
}