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Mina、Netty、Twisted一起学(五):整合protobuf

时间:2014-08-27 11:05:27      阅读:313      评论:0      收藏:0      [点我收藏+]

标签:mina   netty   protobuf   protocol buffers   twisted   

protobuf是谷歌的Protocol Buffers的简称,用于结构化数据和字节码之间互相转换(序列化、反序列化),一般应用于网络传输,可支持多种编程语言。

protobuf如何使用这里不再介绍,本文主要介绍在MINA、Netty、Twisted中如何使用protobuf,不了解protobuf的同学可以去参考我的另一篇博文

前面的一篇博文中,有介绍到一种用一个固定为4字节的前缀Header来指定Body的字节数的一种消息分割方式,在这里同样要使用到。只是其中Body的内容不再是字符串,而是protobuf字节码。

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在处理业务逻辑时,肯定不希望还要对数据进行序列化和反序列化,而是希望直接操作一个对象,那么就需要有相应的编码器和解码器,将序列化和反序列化的逻辑写在编码器和解码器中。有关编码器和解码器的实现,上一篇博文中有介绍。

Netty包中已经自带针对protobuf的编码器和解码器,那么就不用再自己去实现了。而MINA、Twisted还需要自己去实现protobuf的编码器和解码器。

这里定义一个protobuf数据结构,用于描述一个学生的信息,保存为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;
}

用StudentMsg.proto分别生成Java和Python代码,将代码加入到相应的项目中。生成的代码就不再贴上来了。

下面分别介绍在Netty、MINA、Twisted如何使用protobuf来传输Student信息。

Netty:

Netty自带protobuf的编码器和解码器,分别是ProtobufEncoder和ProtobufDecoder。需要注意的是,ProtobufEncoder和ProtobufDecoder只负责protobuf的序列化和反序列化,而处理消息Header前缀和消息分割的还需要LengthFieldBasedFrameDecoder和LengthFieldPrepender。LengthFieldBasedFrameDecoder即用于解析消息Header前缀,根据Header中指定的Body字节数截取Body,LengthFieldPrepender用于在wirte消息时在消息前面添加一个Header前缀来指定Body字节数。

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();
  
							// 负责通过4字节Header指定的Body长度将消息切割
							pipeline.addLast("frameDecoder", 
									new LengthFieldBasedFrameDecoder(1048576, 0, 4, 0, 4));
							
							// 负责将frameDecoder处理后的完整的一条消息的protobuf字节码转成Student对象
							pipeline.addLast("protobufDecoder",
									new ProtobufDecoder(StudentMsg.Student.getDefaultInstance()));

							// 负责将写入的字节码加上4字节Header前缀来指定Body长度
							pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
							
							// 负责将Student对象转成protobuf字节码
							pipeline.addLast("protobufEncoder", new ProtobufEncoder());

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

处理事件时,接收和发送的参数直接就是Student对象:

public class TcpServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
    	
        // 读取客户端传过来的Student对象
    	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);
        }

        // 新建一个Student对象传到客户端
        StudentMsg.Student.Builder builder = StudentMsg.Student.newBuilder();
        builder.setId(9);
        builder.setName("服务器");
        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();
    }
}

MINA:

在MINA中没有针对protobuf的编码器和解码器,但是可以自己实现一个功能和Netty一样的编码器和解码器。

编码器:

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对象转为protobuf字节码
        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);
    }
}

解码器:

public class MinaProtobufDecoder extends CumulativeProtocolDecoder {

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

		// 如果没有接收完Header部分(4字节),直接返回false
		if (in.remaining() < 4) {
			return false;
		} else {

			// 标记开始位置,如果一条消息没传输完成则返回到这个位置
			in.mark();

			// 读取header部分,获取body长度
			int bodyLength = in.getInt();

			// 如果body没有接收完整,直接返回false
			if (in.remaining() < bodyLength) {
				in.reset(); // IoBuffer position回到原来标记的地方
				return false;
			} else {
				byte[] bodyBytes = new byte[bodyLength];
				in.get(bodyBytes); // 读取body部分
				StudentMsg.Student student = StudentMsg.Student.parseFrom(bodyBytes); // 将body中protobuf字节码转成Student对象
				out.write(student); // 解析出一条消息
				return true;
			}
		}
	}
}

MINA服务器加入protobuf的编码器和解码器:

public class TcpServer {

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

        // 指定protobuf的编码器和解码器
        acceptor.getFilterChain().addLast("codec",
                new ProtocolCodecFilter(new MinaProtobufEncoder(), new MinaProtobufDecoder()));

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

这样,在处理业务逻辑时,就和Netty一样了:

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 {

    	// 读取客户端传过来的Student对象
    	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);
        }

        // 新建一个Student对象传到客户端
        StudentMsg.Student.Builder builder = StudentMsg.Student.newBuilder();
        builder.setId(9);
        builder.setName("服务器");
        builder.setEmail("123@abc.com");
        builder.addFriends("X");
        builder.addFriends("Y");
        StudentMsg.Student student2 = builder.build();
        session.write(student2);
    }
}

Twisted:

在Twisted中,首先定义一个ProtobufProtocol类,继承Protocol类,充当编码器和解码器。处理业务逻辑的TcpServerHandle类再继承ProtobufProtocol类,调用或重写ProtobufProtocol提供的方法。

# -*- 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编码、解码器
class ProtobufProtocol(Protocol):

    # 用于暂时存放接收到的数据
    _buffer = b""

    def dataReceived(self, data):
        # 上次未处理的数据加上本次接收到的数据
        self._buffer = self._buffer + data
        # 一直循环直到新的消息没有接收完整
        while True:
            # 如果header接收完整
            if len(self._buffer) >= 4:
                # header部分,按大字节序转int,获取body长度
                length, = unpack(">I", self._buffer[0:4])
                # 如果body接收完整
                if len(self._buffer) >= 4 + length:
                    # body部分,protobuf字节码
                    packet = self._buffer[4:4 + length]
                    
                    # protobuf字节码转成Student对象
                    student = StudentMsg_pb2.Student()
                    student.ParseFromString(packet)
                    
                    # 调用protobufReceived传入Student对象
                    self.protobufReceived(student)
                    
                    # 去掉_buffer中已经处理的消息部分
                    self._buffer = self._buffer[4 + length:]
                else:
                    break;
            else:
                break;

    def protobufReceived(self, student):
        raise NotImplementedError

    def sendProtobuf(self, student):
        # Student对象转为protobuf字节码
        data = student.SerializeToString()
        # 添加Header前缀指定protobuf字节码长度
        self.transport.write(pack(">I", len(data)) + data)

# 逻辑代码
class TcpServerHandle(ProtobufProtocol):

    # 实现ProtobufProtocol提供的protobufReceived
    def protobufReceived(self, student):

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

        # 创建一个Student并发送给客户端
        student2 = StudentMsg_pb2.Student()
        student2.id = 9
        student2.name = ‘服务器‘.decode(‘UTF-8‘) # 中文需要转成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()


下面是Java编写的一个客户端测试程序:

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());
            
            // 创建一个Student传给服务器
            StudentMsg.Student.Builder builder = StudentMsg.Student.newBuilder();
            builder.setId(1);
            builder.setName("客户端");
            builder.setEmail("xxg@163.com");
            builder.addFriends("A");
            builder.addFriends("B");
            StudentMsg.Student student = builder.build();
            byte[] outputBytes = student.toByteArray(); // Student转成字节码
            out.writeInt(outputBytes.length); // write header
            out.write(outputBytes); // write body
            out.flush();
            
            // 获取服务器传过来的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字节码解析成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 {
            // 关闭连接
            in.close();
            out.close();
            socket.close();
        }
    }
}

用客户端分别测试上面三个TCP服务器:

服务器输出:

ID:1
Name:客户端
Email:xxg@163.com
Friends:
A
B

客户端输出:

Header:32
Body:
ID:9
Name:服务器
Email:123@abc.com
Friends:
X
Y


作者:叉叉哥   转载请注明出处:http://blog.csdn.net/xiao__gui/article/details/38864961


Mina、Netty、Twisted一起学(五):整合protobuf

标签:mina   netty   protobuf   protocol buffers   twisted   

原文地址:http://blog.csdn.net/xiao__gui/article/details/38864961

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