NIO

nio 建立緩衝區的方法選擇

allocate 仍是 allocateDirect

http://stevex.blog.51cto.com/4300375/1582209

NIO讀寫文件優劣

http://blog.csdn.net/gzu_imis/article/details/21109753

NIO讀取

public static void main(String[] args)
    {
        ByteBuffer bb = ByteBuffer.allocate(10);
        bb.put(ByteBuffer.wrap("abc".getBytes()));
        byte[] bytes = new byte[1024];
        int postion = bb.position();
        bb.flip();
        //讀取bb的postion 到 limit 之間的數據
        bb.get(bytes, 0, postion);
        // 輸出abc
        System.out.println(new String(bytes));
    }

ByteBuffer.get() 源碼 HeapByteBuffer

public ByteBuffer get(byte[] dst, int offset, int length) {
 checkBounds(offset, length, dst.length);
 if (length > remaining())
    throw new BufferUnderflowException();
 System.arraycopy(hb, ix(position()), dst, offset, length);
 position(position() + length);
 return this;
    }

能夠看到是從緩衝區的position 位置開始讀取數據的，因此須要先作一步bb.flip 才能夠讀取數據