序

本文主要小结一下通信协议设计的要点。

考虑点

1、采用什么传输协议

TCP还是UDP还是HTTP，即在哪一层进行传输

2、采用什么传输格式

即编码协议及序列化方式

（1）采用什么字符集编码/解码

3、消息的设计

（1）消息头

定长，包括消息版本号（1字节）、消息序列号（4字节整型）、消息数据长度（可设计为包含消息类型块的长度，或者仅仅是消息体的长度）、消息延续标志（是/否，消息超长处理用）

（2）消息类型块

请求类型：响应类型、消息体长度    回复类型：响应类型、消息体长度、错误信息（错误号、错误类型、错误内容）、消息处理标志

（3）消息体

实例

Message对象

public class XMessage {    private EncodeEnum encode;    private int length;    private String content;    public void writeUtf8(String msg){        this.encode = EncodeEnum.UTF8;        this.content = msg;        this.length = msg.length();    }    public EncodeEnum getEncode() {        return encode;    }    public void setEncode(EncodeEnum encode) {        this.encode = encode;    }    public int getLength() {        return length;    }    public void setLength(int length) {        this.length = length;    }    public String getContent() {        return content;    }    public void setContent(String content) {        this.content = content;    }    @Override    public String toString() {        return "XMessage{" +                "encode=" + encode +                ", length=" + length +                ", content='" + content + '\'' +                '}';    }}

编解码

public class XProtocol {    public static void encode(OutputStream outputStream,XMessage xMessage) throws IOException {        //write encoding        DataOutputStream dout = new DataOutputStream(outputStream);        dout.writeInt(xMessage.getEncode().ordinal());        //write content length        dout.writeInt(xMessage.getLength());        //write content        dout.write(xMessage.getContent().getBytes(xMessage.getEncode().desc));    }    public static XMessage decode(InputStream input) throws IOException {        DataInputStream din = new DataInputStream(input);        XMessage xMessage = new XMessage();        //get encoding        int encode = din.readInt();        EncodeEnum encodeEnum = EncodeEnum.getByIdx(encode);        xMessage.setEncode(encodeEnum);        //get content length        int length = din.readInt();        xMessage.setLength(length);        //get content        byte[] data = new byte[length];        din.read(data);        String content = new String(data,encodeEnum.desc);        xMessage.setContent(content);        return xMessage;    }}

Server端

public class XServer {    public static void main(String[] args) throws IOException {        ServerSocket server = new ServerSocket(9090);        System.out.println("server running");        while(true){            Socket socket = server.accept();            InputStream inputStream = socket.getInputStream();            XMessage inMsg =XProtocol.decode(inputStream);            System.out.println("receive from client:"+inMsg);            OutputStream outputStream = socket.getOutputStream();            XMessage outMsg = new XMessage();            outMsg.writeUtf8("got our msg");            XProtocol.encode(outputStream,outMsg);            socket.close();        }    }}

Client端

public class XClient {    public static void main(String[] args) throws IOException {        Socket socket = new Socket("127.0.0.1",9090);        OutputStream out = socket.getOutputStream();        XMessage outMsg = new XMessage();        outMsg.writeUtf8("hello server");        XProtocol.encode(out,outMsg);        InputStream inputStream = socket.getInputStream();        XMessage inMsg = XProtocol.decode(inputStream);        System.out.println("receive from server:"+inMsg);    }}

本工程

其他

待补充