JAVA NIO技术壁垒

public static void server(){
       ServerSocket serverSocket = null;
       InputStream in = null;
       try
       {
           serverSocket = new ServerSocket(8080);
           int recvMsgSize = 0;
           byte[] recvBuf = new byte[1024];
           while(true){
               Socket clntSocket = serverSocket.accept();
               SocketAddress clientAddress = clntSocket.getRemoteSocketAddress();
               System.out.println("Handling client at "+clientAddress);
               in = clntSocket.getInputStream();
               while((recvMsgSize=in.read(recvBuf))!=-1){
                   byte[] temp = new byte[recvMsgSize];
                   System.arraycopy(recvBuf, 0, temp, 0, recvMsgSize);
                   System.out.println(new String(temp));
               }
           }
       }
       catch (IOException e)
       {
           e.printStackTrace();
       }
       finally{
           try{
               if(serverSocket!=null){
                   serverSocket.close();
               }
               if(in!=null){
                   in.close();
               }
           }catch(IOException e){
               e.printStackTrace();
           }
       }
   }

public class ServerConnect
{
    private static final int BUF_SIZE=1024;
    private static final int PORT = 8080;
    private static final int TIMEOUT = 3000;
 
    public static void main(String[] args)
    {
        selector();
    }
 
    public static void handleAccept(SelectionKey key) throws IOException{
        ServerSocketChannel ssChannel = (ServerSocketChannel)key.channel();
        SocketChannel sc = ssChannel.accept();
        sc.configureBlocking(false);
        sc.register(key.selector(), SelectionKey.OP_READ,ByteBuffer.allocateDirect(BUF_SIZE));
    }
 
    public static void handleRead(SelectionKey key) throws IOException{
        SocketChannel sc = (SocketChannel)key.channel();
        ByteBuffer buf = (ByteBuffer)key.attachment();
        long bytesRead = sc.read(buf);
        while(bytesRead>0){
            buf.flip();
            while(buf.hasRemaining()){
                System.out.print((char)buf.get());
            }
            System.out.println();
            buf.clear();
            bytesRead = sc.read(buf);
        }
        if(bytesRead == -1){
            sc.close();
        }
    }
 
    public static void handleWrite(SelectionKey key) throws IOException{
        ByteBuffer buf = (ByteBuffer)key.attachment();
        buf.flip();
        SocketChannel sc = (SocketChannel) key.channel();
        while(buf.hasRemaining()){
            sc.write(buf);
        }
        buf.compact();
    }
 
    public static void selector() {
        Selector selector = null;
        ServerSocketChannel ssc = null;
        try{
            selector = Selector.open();
            ssc= ServerSocketChannel.open();
            ssc.socket().bind(new InetSocketAddress(PORT));
            ssc.configureBlocking(false);
            ssc.register(selector, SelectionKey.OP_ACCEPT);
 
            while(true){
                if(selector.select(TIMEOUT) == 0){
                    System.out.println("==");
                    continue;
                }
                Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
                while(iter.hasNext()){
                    SelectionKey key = iter.next();
                    if(key.isAcceptable()){
                        handleAccept(key);
                    }
                    if(key.isReadable()){
                        handleRead(key);
                    }
                    if(key.isWritable() && key.isValid()){
                        handleWrite(key);
                    }
                    if(key.isConnectable()){
                        System.out.println("isConnectable = true");
                    }
                    iter.remove();
                }
            }
 
        }catch(IOException e){
            e.printStackTrace();
        }finally{
            try{
                if(selector!=null){
                    selector.close();
                }
                if(ssc!=null){
                    ssc.close();
                }
            }catch(IOException e){
                e.printStackTrace();
            }
        }
    }
}

ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.socket().bind(new InetSocketAddress(9999));
        serverSocketChannel.configureBlocking(false);
        while (true)
        {
            SocketChannel socketChannel = serverSocketChannel.accept();
            if (socketChannel != null)
            {
                // do something with socketChannel...
            }
        }

public static void method4(){
      RandomAccessFile aFile = null;
      FileChannel fc = null;
      try{
          aFile = new RandomAccessFile("src/1.ppt","rw");
          fc = aFile.getChannel();
 
          long timeBegin = System.currentTimeMillis();
          ByteBuffer buff = ByteBuffer.allocate((int) aFile.length());
          buff.clear();
          fc.read(buff);
          //System.out.println((char)buff.get((int)(aFile.length()/2-1)));
          //System.out.println((char)buff.get((int)(aFile.length()/2)));
          //System.out.println((char)buff.get((int)(aFile.length()/2)+1));
          long timeEnd = System.currentTimeMillis();
          System.out.println("Read time: "+(timeEnd-timeBegin)+"ms");
 
      }catch(IOException e){
          e.printStackTrace();
      }finally{
          try{
              if(aFile!=null){
                  aFile.close();
              }
              if(fc!=null){
                  fc.close();
              }
          }catch(IOException e){
              e.printStackTrace();
          }
      }
  }
 
  public static void method3(){
      RandomAccessFile aFile = null;
      FileChannel fc = null;
      try{
          aFile = new RandomAccessFile("src/1.ppt","rw");
          fc = aFile.getChannel();
          long timeBegin = System.currentTimeMillis();
          MappedByteBuffer mbb = fc.map(FileChannel.MapMode.READ_ONLY, 0, aFile.length());
          // System.out.println((char)mbb.get((int)(aFile.length()/2-1)));
          // System.out.println((char)mbb.get((int)(aFile.length()/2)));
          //System.out.println((char)mbb.get((int)(aFile.length()/2)+1));
          long timeEnd = System.currentTimeMillis();
          System.out.println("Read time: "+(timeEnd-timeBegin)+"ms");
      }catch(IOException e){
          e.printStackTrace();
      }finally{
          try{
              if(aFile!=null){
                  aFile.close();
              }
              if(fc!=null){
                  fc.close();
              }
          }catch(IOException e){
              e.printStackTrace();
          }
      }
  }

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channel;
import java.nio.channels.FileChannel;
 
public class ScattingAndGather
{
    public static void main(String args[]){
        gather();
    }
 
    public static void gather()
    {
        ByteBuffer header = ByteBuffer.allocate(10);
        ByteBuffer body = ByteBuffer.allocate(10);
 
        byte [] b1 = {‘0‘, ‘1‘};
        byte [] b2 = {‘2‘, ‘3‘};
        header.put(b1);
        body.put(b2);
 
        ByteBuffer [] buffs = {header, body};
 
        try
        {
            FileOutputStream os = new FileOutputStream("src/scattingAndGather.txt");
            FileChannel channel = os.getChannel();
            channel.write(buffs);
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }
}

public static void method1(){
        RandomAccessFile fromFile = null;
        RandomAccessFile toFile = null;
        try
        {
            fromFile = new RandomAccessFile("src/fromFile.xml","rw");
            FileChannel fromChannel = fromFile.getChannel();
            toFile = new RandomAccessFile("src/toFile.txt","rw");
            FileChannel toChannel = toFile.getChannel();
 
            long position = 0;
            long count = fromChannel.size();
            System.out.println(count);
            toChannel.transferFrom(fromChannel, position, count);
 
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        finally{
            try{
                if(fromFile != null){
                    fromFile.close();
                }
                if(toFile != null){
                    toFile.close();
                }
            }
            catch(IOException e){
                e.printStackTrace();
            }
        }
    }

public static void method2()
   {
       RandomAccessFile fromFile = null;
       RandomAccessFile toFile = null;
       try
       {
           fromFile = new RandomAccessFile("src/fromFile.txt","rw");
           FileChannel fromChannel = fromFile.getChannel();
           toFile = new RandomAccessFile("src/toFile.txt","rw");
           FileChannel toChannel = toFile.getChannel();
 
           long position = 0;
           long count = fromChannel.size();
           System.out.println(count);
           fromChannel.transferTo(position, count,toChannel);
 
       }
       catch (IOException e)
       {
           e.printStackTrace();
       }
       finally{
           try{
               if(fromFile != null){
                   fromFile.close();
               }
               if(toFile != null){
                   toFile.close();
               }
           }
           catch(IOException e){
               e.printStackTrace();
           }
       }
   }

public static void method1(){
        Pipe pipe = null;
        ExecutorService exec = Executors.newFixedThreadPool(2);
        try{
            pipe = Pipe.open();
            final Pipe pipeTemp = pipe;
 
            exec.submit(new Callable<Object>(){
                @Override
                public Object call() throws Exception
                {
                    Pipe.SinkChannel sinkChannel = pipeTemp.sink();//向通道中写数据
                    while(true){
                        TimeUnit.SECONDS.sleep(1);
                        String newData = "Pipe Test At Time "+System.currentTimeMillis();
                        ByteBuffer buf = ByteBuffer.allocate(1024);
                        buf.clear();
                        buf.put(newData.getBytes());
                        buf.flip();
 
                        while(buf.hasRemaining()){
                            System.out.println(buf);
                            sinkChannel.write(buf);
                        }
                    }
                }
            });
 
            exec.submit(new Callable<Object>(){
                @Override
                public Object call() throws Exception
                {
                    Pipe.SourceChannel sourceChannel = pipeTemp.source();//向通道中读数据
                    while(true){
                        TimeUnit.SECONDS.sleep(1);
                        ByteBuffer buf = ByteBuffer.allocate(1024);
                        buf.clear();
                        int bytesRead = sourceChannel.read(buf);
                        System.out.println("bytesRead="+bytesRead);
                        while(bytesRead >0 ){
                            buf.flip();
                            byte b[] = new byte[bytesRead];
                            int i=0;
                            while(buf.hasRemaining()){
                                b[i]=buf.get();
                                System.out.printf("%X",b[i]);
                                i++;
                            }
                            String s = new String(b);
                            System.out.println("=================||"+s);
                            bytesRead = sourceChannel.read(buf);
                        }
                    }
                }
            });
        }catch(IOException e){
            e.printStackTrace();
        }finally{
            exec.shutdown();
        }
    }

public static void  reveive(){
       DatagramChannel channel = null;
       try{
           channel = DatagramChannel.open();
           channel.socket().bind(new InetSocketAddress(8888));
           ByteBuffer buf = ByteBuffer.allocate(1024);
           buf.clear();
           channel.receive(buf);
 
           buf.flip();
           while(buf.hasRemaining()){
               System.out.print((char)buf.get());
           }
           System.out.println();
 
       }catch(IOException e){
           e.printStackTrace();
       }finally{
           try{
               if(channel!=null){
                   channel.close();
               }
           }catch(IOException e){
               e.printStackTrace();
           }
       }
   }
 
   public static void send(){
       DatagramChannel channel = null;
       try{
           channel = DatagramChannel.open();
           String info = "I‘m the Sender!";
           ByteBuffer buf = ByteBuffer.allocate(1024);
           buf.clear();
           buf.put(info.getBytes());
           buf.flip();
 
           int bytesSent = channel.send(buf, new InetSocketAddress("10.10.195.115",8888));
           System.out.println(bytesSent);
       }catch(IOException e){
           e.printStackTrace();
       }finally{
           try{
               if(channel!=null){
                   channel.close();
               }
           }catch(IOException e){
               e.printStackTrace();
           }
       }
   }