JAVA NIO Scatter/Gather（矢量IO），nioscatter

JAVA NIO Scatter/Gather（矢量IO），nioscatter

矢量IO=Scatter/Gather：   在多個緩沖區上實現一個簡單的IO操作。減少或避免了緩沖區拷貝和系統調用（IO)   write：Gather 數據從幾個緩沖區順序抽取並沿著通道發送，就好比全部緩沖區全部連接起來放入一個大的緩沖區進行發送，緩沖區本身不具備gather能力。 read：Scatter 從通道讀取的數據會按順序散布到多個緩沖區，直到緩沖區被填滿或者通道數據讀完。  

 

Gather： Scatter： 示例代碼：  

 1 /**
 2      * channel Gather/Scatter
 3      */
 4     public static void channelGatherScatter(){
 5         ByteBuffer head = ByteBuffer.allocate(4);
 6         ByteBuffer body = ByteBuffer.allocate(100);
 7         RandomAccessFile afile = null;
 8         RandomAccessFile bfile = null;
 9         ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
10         try {
11             afile = new RandomAccessFile("hello.txt", "r");
12             bfile = new RandomAccessFile("hehe.txt", "rw");
13             readWriteLock.readLock().lock();
14             FileChannel fileChannel = afile.getChannel();
15             ByteBuffer[] buffers = {head, body};
16             while (fileChannel.read(buffers) != -1){
17             }
18             head.flip();
19             body.flip();
20             System.out.println(new String(head.array()));
21             System.out.println(new String(body.array()));
22             readWriteLock.readLock().unlock();
23             fileChannel.close();
24             afile.close();
25 
26             readWriteLock.writeLock().lock();
27             FileChannel bfileChannel = bfile.getChannel();
28 
29             while (bfileChannel.write(buffers) > 0){
30             }
31 
32             readWriteLock.writeLock().unlock();
33             bfileChannel.close();
34             bfile.close();
35         }catch (Exception e){
36             e.printStackTrace();
37         }
38     }

  帶offset、length參數重載read write方法，指明從那個buffer開始，共使用多少個buffer。