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Protocol
mina实战Demo – c/s自定义协议传输
Github项目源码
为什么要进行自定义协议传输?
因为传输过程往往不是一个字符串就可以传输全部信息，并且应用程序和网络通信之间存在对象与二进制之间的转换关系。所以需要结合业务编写自定义协议包进行传输。
编写自定义协议的基本步骤
通过mina文档可以看到，要实现自定义协议传输需要实现ProtocolCodecFactory接口，而ProtocolCodecFactory接口有两个抽象方法，getDecoder(IoSession session)
和 getEncoder(IoSession session) 方法。所以要先实现ProtocolDecoder和ProtocolEncoder接口实现编解码器。
1. 自定义协议数据包
协议数据包包含协议头和协议体，协议头保存协议(协议头+协议体)的长度length和版本信息flag;协议体保存协议内容。
public class ProtocolPack {
private int length;
private byte flag;
private String content;
public ProtocolPack(byte flag, String content) {
this.flag = flag;
this.content = content;
int len1 = content==null ? 0 : content.getBytes().length;
this.length = len1 + 5;//协议头的长度：sizeof(int) + sizeof(byte)
}
getter and setters...
}
2. 自定义编码器
编码器将对象转成字节存入缓冲区中，并传递到下一层。
@Override
public void encode(IoSession session, Object msj, ProtocolEncoderOutput out) throws Exception {
ProtocolPack pack = (ProtocolPack) msj;
IoBuffer buff = IoBuffer.allocate(pack.getLength());
buff.setAutoExpand(true);
buff.putInt(pack.getLength());
buff.put(pack.getFlag());
buff.put(pack.getContent().getBytes());
buff.flip();
out.write(buff);
}
3. 自定义解码器
解码器将对应的字节数组解析成对象,在传输过程中可能会出现半包(数据传输不完整)的问题，所以需要一个Context上下文保存传输的buffer,并将Context
放入session中，下次有新的传输来之后就从本类的session中找到上下文，以追加的方式添加buffer
private class Context {
private IoBuffer buff;
private final CharsetDecoder decoder;
constructor...
public void append(IoBuffer in) {
this.getBuff().put(in);
}
public void reset() {
decoder.reset();
}
getters and setters...
}
@Override
public void decode(IoSession ioSession, IoBuffer ioBuffer, ProtocolDecoderOutput out) throws Exception {
final int packHeadlength = 5;
//通过session获取指定上下文，追加方式存入buffer
Context ctx = this.getContext(ioSession);
ctx.append(ioBuffer);
IoBuffer buff = ctx.getBuff();
buff.flip();
//buff至少存储了一个协议包
while(buff.remaining() >= packHeadlength) {
buff.mark();//标记一下当前position,
int length = buff.getInt();
byte flag = buff.get();
if(length < 0 || length > maxPackLength) { //长度不合法
buff.reset();
break;
} else if(length >= packHeadlength && length-packHeadlength <= buff.remaining()) { //长度合法并且当前buff中存储了完整的协议content
int oldLimit = buff.limit();
buff.limit(buff.position() + length - packHeadlength);
String content = buff.getString(ctx.getDecoder());
buff.limit(oldLimit);
ProtocolPack pack = new ProtocolPack(flag,content);
out.write(pack);
} else { //半包
buff.clear();
break;
}
}
if(buff.hasRemaining()) { //buff中还有未读完数据
IoBuffer tmp = IoBuffer.allocate(maxPackLength).setAutoExpand(true);
tmp.put(buff);
tmp.flip();
buff.reset();
buff.put(tmp);
} else {
buff.reset();
}
}
4. 自定义编解码工厂
编解码工厂实例化编解码器
public class ProtocolFactory implements ProtocolCodecFactory {
private com.clxk1997.codec.ProtocolDecoder decoder;
private com.clxk1997.codec.ProtocolEncoder encoder;
public ProtocolFactory(Charset charset) {
this.decoder = new com.clxk1997.codec.ProtocolDecoder(charset);
this.encoder = new com.clxk1997.codec.ProtocolEncoder(charset);
}
getEncoder and getDecoder...
}
5. 服务端
服务端主要实现编解码过滤器，session参数设置，绑定操作
public class ProtocolServer {
private static final int PORT = 7080;
public static void main(String[] args) throws IOException {
IoAcceptor acceptor = new NioSocketAcceptor();
acceptor.getFilterChain().addLast("coderc",new ProtocolCodecFilter(
new ProtocolFactory(Charset.forName("utf-8"))
));
acceptor.getSessionConfig().setReadBufferSize(1024);
acceptor.getSessionConfig().setIdleTime(IdleStatus.BOTH_IDLE,10);
acceptor.setHandler(new ServerHandle());
acceptor.bind(new InetSocketAddress(PORT));
System.out.println("server start.....");
}
}
6. 服务端handle
主要实现了异常捕获、等待时间、消息接收方法
public class ServerHandle extends IoHandlerAdapter {
@Override
public void sessionIdle(IoSession session, IdleStatus status) throws Exception {
System.out.println("server->sessionIdle");
}
@Override
public void exceptionCaught(IoSession session, Throwable cause) throws Exception {
System.out.println("server->exceptionCaught");
}
@Override
public void messageReceived(IoSession session, Object msg) throws Exception {
ProtocolPack pack = (ProtocolPack) msg;
System.out.println("server received: " + pack.toString());
}
}
7. 客户端
客户端除去过滤器，session设置还通过ConnectFuture监听客户端的连接状态，发送数据
public class ProtocolClient {
private static final int PORT = 7080;
private static final String HOST = "127.0.0.1";
static long start = 0;
static long counter = 0;
final static int fil = 100;
public static void main(String[] args) {
IoConnector connector = new NioSocketConnector();
connector.getFilterChain().addLast("coderc",new ProtocolCodecFilter(
new ProtocolFactory(Charset.forName("UTF-8"))
));
connector.getSessionConfig().setIdleTime(IdleStatus.BOTH_IDLE,10);
connector.getSessionConfig().setReadBufferSize(1024);
connector.setHandler(new ClientHandle());
ConnectFuture future = connector.connect(new InetSocketAddress(HOST,PORT));
future.addListener(new IoFutureListener<ConnectFuture>() {
@Override
public void operationComplete(ConnectFuture future) {
if(future.isConnected()) {
IoSession session = future.getSession();
sendDate(session);
}
}
});
}
private static void sendDate(IoSession session) {
start = System.currentTimeMillis();
for(int i = 0; i < fil; i++) {
String content = "Hello Mina:" + i;
ProtocolPack pack = new ProtocolPack((byte)i,content);
session.write(pack);
System.out.println("client send: " + pack.toString());
}
}
}
8. 客户端handle
主要实现了等待时间、消息接收方法
public class ClientHandle extends IoHandlerAdapter {
@Override
public void sessionIdle(IoSession session, IdleStatus status) throws Exception {
if(status == IdleStatus.READER_IDLE) {
session.closeNow();
}
}
@Override
public void messageReceived(IoSession session, Object message) throws Exception {
ProtocolPack pack = (ProtocolPack) message;
System.out.println("client-> " + pack);
}
}