Netty、MINA、Twisted一起學(xué)系列05：整合protobuf

在處理業(yè)務(wù)邏輯時(shí)，肯定不希望還要對(duì)數(shù)據(jù)進(jìn)行序列化和反序列化，而是希望直接操作一個(gè)對(duì)象，那么就需要有相應(yīng)的編碼器和解碼器，將序列化和反序列化的邏輯寫在編碼器和解碼器中。有關(guān)編碼器和解碼器的實(shí)現(xiàn)，上一篇文章中有介紹。

Netty 包中已經(jīng)自帶針對(duì) protobuf 的編碼器和解碼器，那么就不用再自己去實(shí)現(xiàn)了。而 MINA、Twisted 還需要自己去實(shí)現(xiàn) protobuf 的編碼器和解碼器。

這里定義一個(gè)protobuf數(shù)據(jù)結(jié)構(gòu)，用于描述一個(gè)學(xué)生的信息，保存為StudentMsg.proto文件：

message Student {
    // ID
    required int32 id = 1;  

    // 姓名
    required string name = 2;

    // email
    optional string email = 3;

    // 朋友
    repeated string friends = 4;
}

public class TcpServer {

    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch)
                                throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();

              // 負(fù)責(zé)通過(guò)4字節(jié)Header指定的Body長(zhǎng)度將消息切割
              pipeline.addLast("frameDecoder",
                  new LengthFieldBasedFrameDecoder(1048576, 0, 4, 0, 4));

              // 負(fù)責(zé)將frameDecoder處理后的完整的一條消息的protobuf字節(jié)碼轉(zhuǎn)成Student對(duì)象
              pipeline.addLast("protobufDecoder",
                  new ProtobufDecoder(StudentMsg.Student.getDefaultInstance()));

              // 負(fù)責(zé)將寫入的字節(jié)碼加上4字節(jié)Header前綴來(lái)指定Body長(zhǎng)度
              pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));

              // 負(fù)責(zé)將Student對(duì)象轉(zhuǎn)成protobuf字節(jié)碼
              pipeline.addLast("protobufEncoder", new ProtobufEncoder());

                            pipeline.addLast(new TcpServerHandler());
                        }
                    });
            ChannelFuture f = b.bind(8080).sync();
            f.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }
}

public class TcpServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {

        // 讀取客戶端傳過(guò)來(lái)的Student對(duì)象
      StudentMsg.Student student = (StudentMsg.Student) msg;
        System.out.println("ID:" + student.getId());
        System.out.println("Name:" + student.getName());
        System.out.println("Email:" + student.getEmail());
        System.out.println("Friends:");
        List<String> friends = student.getFriendsList();
        for(String friend : friends) {
          System.out.println(friend);
        }

        // 新建一個(gè)Student對(duì)象傳到客戶端
        StudentMsg.Student.Builder builder = StudentMsg.Student.newBuilder();
        builder.setId(9);
        builder.setName("服務(wù)器");
        builder.setEmail("123@abc.com");
        builder.addFriends("X");
        builder.addFriends("Y");
        StudentMsg.Student student2 = builder.build();
        ctx.writeAndFlush(student2);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

public class MinaProtobufEncoder extends ProtocolEncoderAdapter {

    @Override
    public void encode(IoSession session, Object message,
            ProtocolEncoderOutput out) throws Exception {

      StudentMsg.Student student = (StudentMsg.Student) message;
        byte[] bytes = student.toByteArray(); // Student對(duì)象轉(zhuǎn)為protobuf字節(jié)碼
        int length = bytes.length;

        IoBuffer buffer = IoBuffer.allocate(length + 4);
        buffer.putInt(length); // write header
        buffer.put(bytes); // write body
        buffer.flip();
        out.write(buffer);
    }
}

public class MinaProtobufDecoder extends CumulativeProtocolDecoder {

  @Override
  protected boolean doDecode(IoSession session, IoBuffer in,
      ProtocolDecoderOutput out) throws Exception {

    // 如果沒(méi)有接收完Header部分（4字節(jié)），直接返回false
    if (in.remaining() < 4) {
      return false;
    } else {

      // 標(biāo)記開始位置，如果一條消息沒(méi)傳輸完成則返回到這個(gè)位置
      in.mark();

      // 讀取header部分，獲取body長(zhǎng)度
      int bodyLength = in.getInt();

      // 如果body沒(méi)有接收完整，直接返回false
      if (in.remaining() < bodyLength) {
        in.reset(); // IoBuffer position回到原來(lái)標(biāo)記的地方
        return false;
      } else {
        byte[] bodyBytes = new byte[bodyLength];
        in.get(bodyBytes); // 讀取body部分
        StudentMsg.Student student = StudentMsg.Student.parseFrom(bodyBytes); // 將body中protobuf字節(jié)碼轉(zhuǎn)成Student對(duì)象
        out.write(student); // 解析出一條消息
        return true;
      }
    }
  }
}

public class TcpServer {

    public static void main(String[] args) throws IOException {
        IoAcceptor acceptor = new NioSocketAcceptor();

        // 指定protobuf的編碼器和解碼器
        acceptor.getFilterChain().addLast("codec",
                new ProtocolCodecFilter(new MinaProtobufEncoder(), new MinaProtobufDecoder()));

        acceptor.setHandler(new TcpServerHandle());
        acceptor.bind(new InetSocketAddress(8080));
    }
}

public class TcpServerHandle extends IoHandlerAdapter {

    @Override
    public void exceptionCaught(IoSession session, Throwable cause)
            throws Exception {
        cause.printStackTrace();
    }

    @Override
    public void messageReceived(IoSession session, Object message)
            throws Exception {

      // 讀取客戶端傳過(guò)來(lái)的Student對(duì)象
      StudentMsg.Student student = (StudentMsg.Student) message;
        System.out.println("ID:" + student.getId());
        System.out.println("Name:" + student.getName());
        System.out.println("Email:" + student.getEmail());
        System.out.println("Friends:");
        List<String> friends = student.getFriendsList();
        for(String friend : friends) {
          System.out.println(friend);
        }

        // 新建一個(gè)Student對(duì)象傳到客戶端
        StudentMsg.Student.Builder builder = StudentMsg.Student.newBuilder();
        builder.setId(9);
        builder.setName("服務(wù)器");
        builder.setEmail("123@abc.com");
        builder.addFriends("X");
        builder.addFriends("Y");
        StudentMsg.Student student2 = builder.build();
        session.write(student2);
    }
}

# -*- coding:utf-8 –*-

from struct import pack, unpack
from twisted.internet.protocol import Factory
from twisted.internet.protocol import Protocol
from twisted.internet import reactor
import StudentMsg_pb2

# protobuf編碼、解碼器
class ProtobufProtocol(Protocol):

    # 用于暫時(shí)存放接收到的數(shù)據(jù)
    _buffer = b""

    def dataReceived(self, data):
        # 上次未處理的數(shù)據(jù)加上本次接收到的數(shù)據(jù)
        self._buffer = self._buffer + data
        # 一直循環(huán)直到新的消息沒(méi)有接收完整
        while True:
            # 如果header接收完整
            if len(self._buffer) >= 4:
                # header部分，按大字節(jié)序轉(zhuǎn)int，獲取body長(zhǎng)度
                length, = unpack(">I", self._buffer[0:4])
                # 如果body接收完整
                if len(self._buffer) >= 4 + length:
                    # body部分，protobuf字節(jié)碼
                    packet = self._buffer[4:4 + length]

                    # protobuf字節(jié)碼轉(zhuǎn)成Student對(duì)象
                    student = StudentMsg_pb2.Student()
                    student.ParseFromString(packet)

                    # 調(diào)用protobufReceived傳入Student對(duì)象
                    self.protobufReceived(student)

                    # 去掉_buffer中已經(jīng)處理的消息部分
                    self._buffer = self._buffer[4 + length:]
                else:
                    break;
            else:
                break;

    def protobufReceived(self, student):
        raise NotImplementedError

    def sendProtobuf(self, student):
        # Student對(duì)象轉(zhuǎn)為protobuf字節(jié)碼
        data = student.SerializeToString()
        # 添加Header前綴指定protobuf字節(jié)碼長(zhǎng)度
        self.transport.write(pack(">I", len(data)) + data)

# 邏輯代碼
class TcpServerHandle(ProtobufProtocol):

    # 實(shí)現(xiàn)ProtobufProtocol提供的protobufReceived
    def protobufReceived(self, student):

        # 將接收到的Student輸出
        print 'ID:' + str(student.id)
        print 'Name:' + student.name
        print 'Email:' + student.email
        print 'Friends:'
        for friend in student.friends:
            print friend

        # 創(chuàng)建一個(gè)Student并發(fā)送給客戶端
        student2 = StudentMsg_pb2.Student()
        student2.id = 9
        student2.name = '服務(wù)器'.decode('UTF-8') # 中文需要轉(zhuǎn)成UTF-8字符串
        student2.email = '123@abc.com'
        student2.friends.append('X')
        student2.friends.append('Y')
        self.sendProtobuf(student2)

factory = Factory()
factory.protocol = TcpServerHandle
reactor.listenTCP(8080, factory)
reactor.run()

public class TcpClient {

    public static void main(String[] args) throws IOException {

        Socket socket = null;
        DataOutputStream out = null;
        DataInputStream in = null;

        try {

            socket = new Socket("localhost", 8080);
            out = new DataOutputStream(socket.getOutputStream());
            in = new DataInputStream(socket.getInputStream());

            // 創(chuàng)建一個(gè)Student傳給服務(wù)器
            StudentMsg.Student.Builder builder = StudentMsg.Student.newBuilder();
            builder.setId(1);
            builder.setName("客戶端");
            builder.setEmail("xxg@163.com");
            builder.addFriends("A");
            builder.addFriends("B");
            StudentMsg.Student student = builder.build();
            byte[] outputBytes = student.toByteArray(); // Student轉(zhuǎn)成字節(jié)碼
            out.writeInt(outputBytes.length); // write header
            out.write(outputBytes); // write body
            out.flush();

            // 獲取服務(wù)器傳過(guò)來(lái)的Student
            int bodyLength = in.readInt();  // read header
            byte[] bodyBytes = new byte[bodyLength];
            in.readFully(bodyBytes);  // read body
            StudentMsg.Student student2 = StudentMsg.Student.parseFrom(bodyBytes); // body字節(jié)碼解析成Student
            System.out.println("Header:" + bodyLength);
            System.out.println("Body:");
            System.out.println("ID:" + student2.getId());
            System.out.println("Name:" + student2.getName());
            System.out.println("Email:" + student2.getEmail());
            System.out.println("Friends:");
            List<String> friends = student2.getFriendsList();
            for(String friend : friends) {
              System.out.println(friend);
            }

        } finally {
            // 關(guān)閉連接
            in.close();
            out.close();
            socket.close();
        }
    }
}

ID:1

Name:客戶端

Email:xxg@163.com

Friends:

A

B

Header:32

Body:

ID:9

Name:服務(wù)器

Email:123@abc.com

Friends:

X

Y