producer.java

java可以实现内存共享的

package sharememory;

import java.io.*;
import java.nio.*;
import java.nio.channels.*;

public class Producer extends Thread
{
    private String mFileName;
    private FileChannel mFileChannel;
    private MappedByteBuffer mMappedByteBuffer;

    public Producer(String fn)
    {
        try
        {
            mFileName=fn;

            // 获得一个可读写的随机存取文件对象
            RandomAccessFile RAFile=new RandomAccessFile(mFileName,"rw");

            // 获得相应的文件通道
            mFileChannel=RAFile.getChannel();

            // 取得文件的实际大小，以便映像到共享内存
            int size=(int)mFileChannel.size();

            // 获得共享内存缓冲区，该共享内存可读
            mMappedByteBuffer=mFileChannel.map(FileChannel.MapMode.READ_WRITE,0,size).load();
        }
        catch(IOException ex)
        {
            System.out.println(ex);
        }
    }

    public void run()
    {
        int i=0;
        while(true)
        {
            try
            {
                FileLock lock=null;
                lock=mFileChannel.tryLock();
                if(lock==null)
                {
                    System.err.println("Producer: lock failed");
                    continue;
                }
                mMappedByteBuffer.putInt(++i);
                mMappedByteBuffer.putInt(++i);
                mMappedByteBuffer.putInt(++i);
                //mMappedByteBuffer.putInt(12,++i);
                System.out.println("Producer: "+(i-3)+":"+(i-2)+":"+(i-1));
                Thread.sleep(200);
                lock.release();
                Thread.sleep(500);
            }
            catch(IOException ex)
            {
                System.out.print(ex);
            }
            catch(InterruptedException ex)
            {
                System.out.print(ex);
            }
        }

    }

    public static void main(String args[])
    {
        Producer producer=new Producer("sharedMemory.bin");
        producer.start();
    }

}