RPC-Thrift（二）

　　TTransport

　　　　TTransport负责数据的传输，先看类结构图。

　　　　　　

　　　　阻塞Server使用TServerSocket，它封装了ServerSocket实例，ServerSocket实例监听到客户端的请求会创建一个Socket对象，并将该Socket对象封装为一个TSocket对象用于通信。

　　　　非阻塞Server使用TNonblockingServerSocket，它封装了一个ServerSocketChannel实例，ServerSocketChannel实例监听到客户端的请求会创建一个SocketChannel对象，并将该对象封装成一个TNonblockingSocket对象用于之后的通信。当读取完客户端的请求数据后，保存为本地的一个TTransport对象，然后封装为TFramedTransport对象进行处理。

　　　　TTransport

　　　　　　TTransport是客户端所有Transport的基类。

public abstract class TTransport {
  public abstract boolean isOpen();//transport是否打开
  public boolean peek() {//是否还有数据要读，如果transport打开时还有数据要读
    return isOpen();
  }
  public abstract void open() throws TTransportException;//打开transport读写数据
  public abstract void close();//关闭transport
  //读取len长度的数据到字节数组buf，off表示开始读的位置，返回实际读取的字节数（不一定为len）
  public abstract int read(byte[] buf, int off, int len) throws TTransportException;
  //确保读取len长度的数据到字节数组buf，off表示开始读的位置，通过循环调用read()实现，返回实际读取的字节数（len）
  public int readAll(byte[] buf, int off, int len)
    throws TTransportException {
    int got = 0;
    int ret = 0;
    while (got < len) {
      ret = read(buf, off+got, len-got);
      if (ret <= 0) {
        throw new TTransportException(
            "Cannot read. Remote side has closed. Tried to read "
                + len
                + " bytes, but only got "
                + got
                + " bytes. (This is often indicative of an internal error on the server side. Please check your server logs.)");
      }
      got += ret;
    }
    return got;
  }
  //将buf中的全部数据写到output
  public void write(byte[] buf) throws TTransportException {
    write(buf, 0, buf.length);
  }
  //将buf中off位置开始len长度的数据写到output
  public abstract void write(byte[] buf, int off, int len) throws TTransportException;
  //清空transport缓存中的数据
  public void flush() throws TTransportException {}
  //获取本地缓存的数据，没有则返回null
  public byte[] getBuffer() {
    return null;
  }
  //获取本地缓存的下一个读取位置，没有则返回0
  public int getBufferPosition() {
    return 0;
  }
  //获取本地缓存的字节数，没有则返回-1
  public int getBytesRemainingInBuffer() {
    return -1;
  }
  //从本地缓存中消费n个字节
  public void consumeBuffer(int len) {}
}

　　　　TIOStreamTransport

　　　　　　TIOStreamTransport是面向流的TTransport的子类，阻塞式，实现了流的操作。

public class TIOStreamTransport extends TTransport {
  private static final Logger LOGGER = LoggerFactory.getLogger(TIOStreamTransport.class.getName());
  protected InputStream inputStream_ = null;//输入流
  protected OutputStream outputStream_ = null;//输出流
  //一波构造函数
  protected TIOStreamTransport() {}
  public TIOStreamTransport(InputStream is) {
    inputStream_ = is;
  }
  public TIOStreamTransport(OutputStream os) {
    outputStream_ = os;
  }
  public TIOStreamTransport(InputStream is, OutputStream os) {
    inputStream_ = is;
    outputStream_ = os;
  }
  //streams必须在构造时已经被打开，so一直返回true
  public boolean isOpen() {
    return true;
  }
  //streams必须在构造时已经被打开，不需要这个方法
  public void open() throws TTransportException {}
  //关闭流
  public void close() {
    if (inputStream_ != null) {
      try {
        inputStream_.close();
      } catch (IOException iox) {
        LOGGER.warn("Error closing input stream.", iox);
      }
      inputStream_ = null;
    }
    if (outputStream_ != null) {
      try {
        outputStream_.close();
      } catch (IOException iox) {
        LOGGER.warn("Error closing output stream.", iox);
      }
      outputStream_ = null;
    }
  }
  //将输入流中的指定数据读取到buf中
  public int read(byte[] buf, int off, int len) throws TTransportException {
    if (inputStream_ == null) {
      throw new TTransportException(TTransportException.NOT_OPEN, "Cannot read from null inputStream");
    }
    int bytesRead;
    try {
      bytesRead = inputStream_.read(buf, off, len);
    } catch (IOException iox) {
      throw new TTransportException(TTransportException.UNKNOWN, iox);
    }
    if (bytesRead < 0) {
      throw new TTransportException(TTransportException.END_OF_FILE);
    }
    return bytesRead;
  }
  //将buf中的数据写出的输出流outputStream_
  public void write(byte[] buf, int off, int len) throws TTransportException {
    if (outputStream_ == null) {
      throw new TTransportException(TTransportException.NOT_OPEN, "Cannot write to null outputStream");
    }
    try {
      outputStream_.write(buf, off, len);
    } catch (IOException iox) {
      throw new TTransportException(TTransportException.UNKNOWN, iox);
    }
  }
  //清空输出流
  public void flush() throws TTransportException {
    if (outputStream_ == null) {
      throw new TTransportException(TTransportException.NOT_OPEN, "Cannot flush null outputStream");
    }
    try {
      outputStream_.flush();
    } catch (IOException iox) {
      throw new TTransportException(TTransportException.UNKNOWN, iox);
    }
  }
}

　　　　TSocket

　　　　　　TSocket类继承自TIOStreamTransport类，实现了对Socket实例的包装。inputStream_和outputStream_通过Socket初始化。

public class TSocket extends TIOStreamTransport {
  private static final Logger LOGGER = LoggerFactory.getLogger(TSocket.class.getName());
  private Socket socket_ = null;//包装socket_
  private String host_  = null;//远程host
  private int port_ = 0;//远程port
  private int timeout_ = 0;//Socket超时时间
  //三个构造函数
  public TSocket(Socket socket) throws TTransportException {
    socket_ = socket;
    try {
      socket_.setSoLinger(false, 0);
      socket_.setTcpNoDelay(true);
    } catch (SocketException sx) {
      LOGGER.warn("Could not configure socket.", sx);
    }

    if (isOpen()) {
      try {
        //初始化inputStream_和outputStream_
        inputStream_ = new BufferedInputStream(socket_.getInputStream(), 1024);
        outputStream_ = new BufferedOutputStream(socket_.getOutputStream(), 1024);
      } catch (IOException iox) {
        close();
        throw new TTransportException(TTransportException.NOT_OPEN, iox);
      }
    }
  }
  public TSocket(String host, int port) {
    this(host, port, 0);
  }
  public TSocket(String host, int port, int timeout) {
    host_ = host;
    port_ = port;
    timeout_ = timeout;
    initSocket();
  }
  //初始化Socket
  private void initSocket() {
    socket_ = new Socket();
    try {
      socket_.setSoLinger(false, 0);
      socket_.setTcpNoDelay(true);
      socket_.setSoTimeout(timeout_);
    } catch (SocketException sx) {
      LOGGER.error("Could not configure socket.", sx);
    }
  }
  public void setTimeout(int timeout) {
    timeout_ = timeout;
    try {
      socket_.setSoTimeout(timeout);
    } catch (SocketException sx) {
      LOGGER.warn("Could not set socket timeout.", sx);
    }
  }
  public Socket getSocket() {
    if (socket_ == null) {
      initSocket();
    }
    return socket_;
  }
  //检查socket_是否连接
  public boolean isOpen() {
    if (socket_ == null) {
      return false;
    }
    return socket_.isConnected();
  }
  //打开socket连接，初始化输入流和输出流
  public void open() throws TTransportException {
    if (isOpen()) {
      throw new TTransportException(TTransportException.ALREADY_OPEN, "Socket already connected.");
    }
    if (host_.length() == 0) {
      throw new TTransportException(TTransportException.NOT_OPEN, "Cannot open null host.");
    }
    if (port_ <= 0) {
      throw new TTransportException(TTransportException.NOT_OPEN, "Cannot open without port.");
    }
    if (socket_ == null) {
      initSocket();
    }
    try {
      socket_.connect(new InetSocketAddress(host_, port_), timeout_);
      inputStream_ = new BufferedInputStream(socket_.getInputStream(), 1024);
      outputStream_ = new BufferedOutputStream(socket_.getOutputStream(), 1024);
    } catch (IOException iox) {
      close();
      throw new TTransportException(TTransportException.NOT_OPEN, iox);
    }
  }
  //关闭socket
  public void close() {
    super.close();
    if (socket_ != null) {
      try {
        socket_.close();
      } catch (IOException iox) {
        LOGGER.warn("Could not close socket.", iox);
      }
      socket_ = null;
    }
  }
}

　　　　TFramedTransport

　　　　　　TFramedTransport作用是通过message之前的4-byte frame size确保读到的message时完整的，防止发生粘包拆包的问题。

//TFramedTransport作用是通过message之前的4-byte frame size确保读到的message时完整的，防止发生粘包拆包的问题
public class TFramedTransport extends TTransport {
  protected static final int DEFAULT_MAX_LENGTH = 16384000;//默认的本地缓存最大字节数
  private int maxLength_;//本地缓存最大字节数
  private TTransport transport_ = null;//封装的transport_，实际通过该对象实现数据的读取与写入
  private final TByteArrayOutputStream writeBuffer_ = new TByteArrayOutputStream(1024);//输出BUffer，将字节数组输出
  private TMemoryInputTransport readBuffer_ = new TMemoryInputTransport(new byte[0]);//输入buffer，用于数据读取
  //工厂类，用于将一个TTransport实例封装为TFramedTransport实例
  public static class Factory extends TTransportFactory {
    private int maxLength_;
    public Factory() {
      maxLength_ = TFramedTransport.DEFAULT_MAX_LENGTH;
    }
    public Factory(int maxLength) {
      maxLength_ = maxLength;
    }
    @Override
    public TTransport getTransport(TTransport base) {
      return new TFramedTransport(base, maxLength_);
    }
  }
  //两个构造函数
  public TFramedTransport(TTransport transport, int maxLength) {
    transport_ = transport;
    maxLength_ = maxLength;
  }
  public TFramedTransport(TTransport transport) {
    transport_ = transport;
    maxLength_ = TFramedTransport.DEFAULT_MAX_LENGTH;
  }
  //同transport_的三个方法
  public void open() throws TTransportException {
    transport_.open();
  }
  public boolean isOpen() {
    return transport_.isOpen();
  }
  public void close() {
    transport_.close();
  }
  //读数据，一次请求可能调用多次
  public int read(byte[] buf, int off, int len) throws TTransportException {
    if (readBuffer_ != null) {
      //在一次客户端的请求中第一次调用该方法时，肯定返回got<0，就可以进入 readFrame()方法。
      int got = readBuffer_.read(buf, off, len);//readBuffer_已读完或字节数为0时 肯定返回got<0
      if (got > 0) {
        return got;
      }
    }
    readFrame();//从transport_读到本地缓存readBuffer_
    return readBuffer_.read(buf, off, len);
  }
  @Override
  public byte[] getBuffer() {
    return readBuffer_.getBuffer();
  }
  @Override
  public int getBufferPosition() {
    return readBuffer_.getBufferPosition();
  }
  @Override
  public int getBytesRemainingInBuffer() {
    return readBuffer_.getBytesRemainingInBuffer();
  }
  @Override
  public void consumeBuffer(int len) {
    readBuffer_.consumeBuffer(len);
  }

  private final byte[] i32buf = new byte[4];

  private void readFrame() throws TTransportException {
    transport_.readAll(i32buf, 0, 4); //读前4个字节，FrameSize
    int size = decodeFrameSize(i32buf);//由于发送数据方对FrameSize进行了编码，通过解码得到消息的大小
    //校验FrameSize是否正确
    if (size < 0) {
      throw new TTransportException("Read a negative frame size (" + size + ")!");
    }
    if (size > maxLength_) {
      throw new TTransportException("Frame size (" + size + ") larger than max length (" + maxLength_ + ")!");
    }
    byte[] buff = new byte[size];
    transport_.readAll(buff, 0, size);//将FrameSize大小的全部数据读到buff
    readBuffer_.reset(buff);//重置本地缓存
  }
  //write是向本地缓存写入数据，写完后，所有的调用方都要对输出流调用flush进行清空，所以下面一定会进入到flush方法，再通过transport_将本地缓存的数据写出去
  public void write(byte[] buf, int off, int len) throws TTransportException {
    writeBuffer_.write(buf, off, len);
  }
  @Override
  public void flush() throws TTransportException {
    byte[] buf = writeBuffer_.get();
    int len = writeBuffer_.len();
    writeBuffer_.reset();//清空
    encodeFrameSize(len, i32buf);//对FrameSize进行编码
    transport_.write(i32buf, 0, 4);//先写数据大小FrameSize
    transport_.write(buf, 0, len);//在写真实数据
    transport_.flush();//清空
  }
  //以下两个方法是对FrameSize进行编解码，将每个字节高位都位移到低位组成byte数组
  public static final void encodeFrameSize(final int frameSize, final byte[] buf) {
    buf[0] = (byte)(0xff & (frameSize >> 24));
    buf[1] = (byte)(0xff & (frameSize >> 16));
    buf[2] = (byte)(0xff & (frameSize >> 8));
    buf[3] = (byte)(0xff & (frameSize));
  }
  public static final int decodeFrameSize(final byte[] buf) {
    return 
      ((buf[0] & 0xff) << 24) |
      ((buf[1] & 0xff) << 16) |
      ((buf[2] & 0xff) <<  8) |
      ((buf[3] & 0xff));
  }
}

 　　　　　　TFramedTransport用到了TMemoryInputTransport类，TMemoryInputTransport封装了一个字节数组byte[]来做输入流的封装。

public final class TMemoryInputTransport extends TTransport {
  private byte[] buf_;//保存数据的字节数组
  private int pos_;//可读数据的开始位置
  private int endPos_;//可读数据的的结束位置
  public TMemoryInputTransport() {
  }
  public TMemoryInputTransport(byte[] buf) {
    reset(buf);
  }
  public TMemoryInputTransport(byte[] buf, int offset, int length) {
    reset(buf, offset, length);
  }
  //重置buf
  public void reset(byte[] buf) {
    reset(buf, 0, buf.length);
  }
  public void reset(byte[] buf, int offset, int length) {
    buf_ = buf;
    pos_ = offset;
    endPos_ = offset + length;
  }
  public void clear() {
    buf_ = null;
  }
  @Override
  public void close() {}
  @Override
  public boolean isOpen() {
    return true;
  }
  @Override
  public void open() throws TTransportException {}
  @Override
  public int read(byte[] buf, int off, int len) throws TTransportException {
    int bytesRemaining = getBytesRemainingInBuffer();//获取剩余可读的数据大小
    int amtToRead = (len > bytesRemaining ? bytesRemaining : len);
    if (amtToRead > 0) {
      System.arraycopy(buf_, pos_, buf, off, amtToRead);//将buf_中pos_开始的amtToRead个字节copy到buf中
      consumeBuffer(amtToRead);//将可读数据的开始位置增加amtToRead
    }
    return amtToRead;
  }
  //不支持写
  @Override
  public void write(byte[] buf, int off, int len) throws TTransportException {
    throw new UnsupportedOperationException("No writing allowed!");
  }
  @Override
  public byte[] getBuffer() {
    return buf_;
  }
  public int getBufferPosition() {
    return pos_;
  }
  //剩余可读的数据大小
  public int getBytesRemainingInBuffer() {
    return endPos_ - pos_;
  }
  //将可读数据的开始位置向后移len
  public void consumeBuffer(int len) {
    pos_ += len;
  }
}

　　　　TNonblockingTransport　　　　

　　　　　　TNonblockingTransport是TTransport的非阻塞抽象子类。

public abstract class TNonblockingTransport extends TTransport {
  //连接初始化，参考SocketChannel.connect
  public abstract boolean startConnect() throws IOException;
  //连接完成，SocketChannel.finishConnect()
  public abstract boolean finishConnect() throws IOException;
  //注册到selector
  public abstract SelectionKey registerSelector(Selector selector, int interests) throws IOException;
  //读数据到buffer中
  public abstract int read(ByteBuffer buffer) throws IOException;
  //将buffer中的数据写出
  public abstract int write(ByteBuffer buffer) throws IOException;
}

　　　　TNonblockingSocket

　　　　　　TNonblockingSocket是TNonblockingTransport的子类，是非阻塞Socket的实现，用于异步客户端。

public class TNonblockingSocket extends TNonblockingTransport {
  private static final Logger LOGGER = LoggerFactory.getLogger(TNonblockingSocket.class.getName());
  private final SocketAddress socketAddress_;//Host and port info，用于非阻塞连接懒加载
  private final SocketChannel socketChannel_;//Java NIO中实现非阻塞读写的核心类
  //一波构造函数
  public TNonblockingSocket(String host, int port) throws IOException {
    this(host, port, 0);
  }
  public TNonblockingSocket(String host, int port, int timeout) throws IOException {
    this(SocketChannel.open(), timeout, new InetSocketAddress(host, port));
  }
  public TNonblockingSocket(SocketChannel socketChannel) throws IOException {
    this(socketChannel, 0, null);
    if (!socketChannel.isConnected()) throw new IOException("Socket must already be connected");
  }
  private TNonblockingSocket(SocketChannel socketChannel, int timeout, SocketAddress socketAddress)
      throws IOException {
    socketChannel_ = socketChannel;
    socketAddress_ = socketAddress;
    socketChannel.configureBlocking(false);//设置socketChannel为非阻塞
    Socket socket = socketChannel.socket();
    socket.setSoLinger(false, 0);
    socket.setTcpNoDelay(true);
    setTimeout(timeout);
  }
  //将SocketChannel注册到selector上的感兴趣事件，当感兴趣事件就绪时会收到notify
  public SelectionKey registerSelector(Selector selector, int interests) throws IOException {
    return socketChannel_.register(selector, interests);
  }
  public void setTimeout(int timeout) {
    try {
      socketChannel_.socket().setSoTimeout(timeout);
    } catch (SocketException sx) {
      LOGGER.warn("Could not set socket timeout.", sx);
    }
  }
  public SocketChannel getSocketChannel() {
    return socketChannel_;
  }
  //检查是否处于连接状态
  public boolean isOpen() {
    // isConnected() does not return false after close(), but isOpen() does
    return socketChannel_.isOpen() && socketChannel_.isConnected();
  }
  //不要调用该方法，该实现类提供了自己的懒加载方法startConnect()用于打开连接
  public void open() throws TTransportException {
    throw new RuntimeException("open() is not implemented for TNonblockingSocket");
  }
  //读数据到buffer中
  public int read(ByteBuffer buffer) throws IOException {
    return socketChannel_.read(buffer);
  }
  //读指定数据到buf中，通过socketChannel_实现
  public int read(byte[] buf, int off, int len) throws TTransportException {
    if ((socketChannel_.validOps() & SelectionKey.OP_READ) != SelectionKey.OP_READ) {
      throw new TTransportException(TTransportException.NOT_OPEN,
        "Cannot read from write-only socket channel");
    }
    try {
      return socketChannel_.read(ByteBuffer.wrap(buf, off, len));
    } catch (IOException iox) {
      throw new TTransportException(TTransportException.UNKNOWN, iox);
    }
  }
  //将buffer中的数据写出
  public int write(ByteBuffer buffer) throws IOException {
    return socketChannel_.write(buffer);
  }
  //将buffer中的指定数据写出
  public void write(byte[] buf, int off, int len) throws TTransportException {
    if ((socketChannel_.validOps() & SelectionKey.OP_WRITE) != SelectionKey.OP_WRITE) {
      throw new TTransportException(TTransportException.NOT_OPEN,
        "Cannot write to write-only socket channel");
    }
    try {
      socketChannel_.write(ByteBuffer.wrap(buf, off, len));
    } catch (IOException iox) {
      throw new TTransportException(TTransportException.UNKNOWN, iox);
    }
  }
  //socketChannel_不支持
  public void flush() throws TTransportException {
  }
  //关闭socket
  public void close() {
    try {
      socketChannel_.close();
    } catch (IOException iox) {
      LOGGER.warn("Could not close socket.", iox);
    }
  }
  //开始初始化
  public boolean startConnect() throws IOException {
    return socketChannel_.connect(socketAddress_);
  }
  //是否完成连接
  public boolean finishConnect() throws IOException {
    return socketChannel_.finishConnect();
  }
}

　　　　TServerTransport

　　　　　　服务端Transport层共同的父类，主要包括开启监听和接收客户端连接请求两个方法。

public abstract class TServerTransport {
  //开启监听客户端连接
  public abstract void listen() throws TTransportException;
  //连接请求到达后，创建transport实例
  public final TTransport accept() throws TTransportException {
    TTransport transport = acceptImpl();//具体方法由子类实现
    if (transport == null) {
      throw new TTransportException("accept() may not return NULL");
    }
    return transport;
  }
  //关闭监听
  public abstract void close();
  protected abstract TTransport acceptImpl() throws TTransportException;
  public void interrupt() {}
}

 　　　　TServerSocket

　　　　　　阻塞服务时使用，TServerSocket对ServerSocket类进行包装，具体实现由TServerSocket完成，代码相对比较简单。

public class TServerSocket extends TServerTransport {
  private static final Logger LOGGER = LoggerFactory.getLogger(TServerSocket.class.getName());
  private ServerSocket serverSocket_ = null;//基于ServerSocket实现
  private int clientTimeout_ = 0;//接收Client连接请求的超时时间
  public TServerSocket(ServerSocket serverSocket) {
    this(serverSocket, 0);
  }
  //几个构造函数略过。。。创建TServerSocket实例
  public TServerSocket(InetSocketAddress bindAddr, int clientTimeout) throws TTransportException {
    clientTimeout_ = clientTimeout;
    try {
      serverSocket_ = new ServerSocket();
      serverSocket_.setReuseAddress(true);
      serverSocket_.bind(bindAddr);// Bind to listening port
    } catch (IOException ioe) {
      serverSocket_ = null;
      throw new TTransportException("Could not create ServerSocket on address " + bindAddr.toString() + ".");
    }
  }
  public void listen() throws TTransportException {
    if (serverSocket_ != null) {
      try {
        serverSocket_.setSoTimeout(0);//等待客户端连接的超时时间，0表示无限超时
      } catch (SocketException sx) {
        LOGGER.error("Could not set socket timeout.", sx);
      }
    }
  }
  //accept客户端连接并封装为TSocket
  protected TSocket acceptImpl() throws TTransportException {
    if (serverSocket_ == null) {
      throw new TTransportException(TTransportException.NOT_OPEN, "No underlying server socket.");
    }
    try {
      Socket result = serverSocket_.accept();
      TSocket result2 = new TSocket(result);
      result2.setTimeout(clientTimeout_);
      return result2;
    } catch (IOException iox) {
      throw new TTransportException(iox);
    }
  }
  //关闭serverSocket_
  public void close() {
    if (serverSocket_ != null) {
      try {
        serverSocket_.close();
      } catch (IOException iox) {
        LOGGER.warn("Could not close server socket.", iox);
      }
      serverSocket_ = null;
    }
  }
  public void interrupt() {
    close();
  }
  public ServerSocket getServerSocket() {
    return serverSocket_;
  }
}

　　　　TNonblockingServerTransport

　　　　　　TNonblockingServerTransport是非阻塞实现的抽象基类，定义了一个向Selector注册对象的抽象方法。

public abstract class TNonblockingServerTransport extends TServerTransport {
  public abstract void registerSelector(Selector selector);
}

　　　　TNonblockingServerSocket

　　　　　　TNonblockingServerSocket是TNonblockingServerTransport的具体实现，对ServerSocketChannel的封装。

public class TNonblockingServerSocket extends TNonblockingServerTransport {
  private static final Logger LOGGER = LoggerFactory.getLogger(TNonblockingServerTransport.class.getName());
  private ServerSocketChannel serverSocketChannel = null;//接收Client请求，Java NIO中的Channel
  private ServerSocket serverSocket_ = null;//serverSocketChannel中的对象
  private int clientTimeout_ = 0;//客户端连接建立超时时间
  //几个构造函数略过。。。创建TNonblockingServerSocket实例
  public TNonblockingServerSocket(InetSocketAddress bindAddr, int clientTimeout) throws TTransportException {
    clientTimeout_ = clientTimeout;
    try {
      serverSocketChannel = ServerSocketChannel.open();//创建serverSocketChannel实例
      serverSocketChannel.configureBlocking(false);//设置为非阻塞
      serverSocket_ = serverSocketChannel.socket();//创建serverSocket_实例
      serverSocket_.setReuseAddress(true);
      serverSocket_.bind(bindAddr);//绑定监听端口
    } catch (IOException ioe) {
      serverSocket_ = null;
      throw new TTransportException("Could not create ServerSocket on address " + bindAddr.toString() + ".");
    }
  }
  //开启监听客户端连接
  public void listen() throws TTransportException {
    if (serverSocket_ != null) {
      try {
        serverSocket_.setSoTimeout(0);//等待客户端连接的超时时间，0表示无限超时
      } catch (SocketException sx) {
        sx.printStackTrace();
      }
    }
  }
  //接收客户端连接的具体实现，接收客户端连接并封装为TNonblockingSocket返回
  protected TNonblockingSocket acceptImpl() throws TTransportException {
    if (serverSocket_ == null) {
      throw new TTransportException(TTransportException.NOT_OPEN, "No underlying server socket.");
    }
    try {
      SocketChannel socketChannel = serverSocketChannel.accept();
      if (socketChannel == null) {
        return null;
      }
      TNonblockingSocket tsocket = new TNonblockingSocket(socketChannel);
      tsocket.setTimeout(clientTimeout_);
      return tsocket;
    } catch (IOException iox) {
      throw new TTransportException(iox);
    }
  }
  //向selector注册OP_ACCEPT事件，接收新的连接
  public void registerSelector(Selector selector) {
    try {
      serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
    } catch (ClosedChannelException e) {
    }
  }
  //关闭serverSocket_
  public void close() {
    if (serverSocket_ != null) {
      try {
        serverSocket_.close();
      } catch (IOException iox) {
        LOGGER.warn("WARNING: Could not close server socket: " + iox.getMessage());
      }
      serverSocket_ = null;
    }
  }
  public void interrupt() {
    close();
  }
}

 　　总结

　　　　注意介绍了TTransport的实现方式。

 参考资料

　　Thrift源码系列----2.TTransport层源码分析