• 協議說明
• 服務端

協議說明

訊息頭4位元組，內容為訊息體位元組長度

服務端

package com.cnblogs.javalouvre;

import org.apache.mina.core.IoUtil;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.filterchain.DefaultIoFilterChainBuilder;
import org.apache.mina.core.service.IoHandlerAdapter;
import org.apache.mina.core.session.IdleStatus;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.*;
import org.apache.mina.filter.executor.ExecutorFilter;
import org.apache.mina.filter.logging.LoggingFilter;
import org.apache.mina.transport.socket.SocketSessionConfig;
import org.apache.mina.transport.socket.nio.NioSocketAcceptor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.StandardCharsets;

public class Server {

    private static final Logger log = LoggerFactory.getLogger(Server.class);

    public static void main(String[] args) {
        final NioSocketAcceptor acceptor = new NioSocketAcceptor();
        final DefaultIoFilterChainBuilder filterChain = acceptor.getFilterChain();
        // 編碼、解碼過濾器
        filterChain.addLast("codec", new ProtocolCodecFilter(new MessageProtocolCodecFactory()));
        // 日誌過濾器
        filterChain.addLast("logger", new LoggingFilter());
        // 把耗時操作放入單獨執行緒池中
        filterChain.addLast("executor", new ExecutorFilter());
        final SocketSessionConfig sessionConfig = acceptor.getSessionConfig();
        sessionConfig.setMaxReadBufferSize(100);
        sessionConfig.setIdleTime(IdleStatus.BOTH_IDLE, 10);
        acceptor.setHandler(new IoHandlerAdapter() {

            @Override
            public void messageReceived(IoSession session, Object message) throws Exception {
                log.info("服務端收到訊息: {}", message);

                // 對當前所有連線的session廣播
                IoUtil.broadcast("...BOOM...", session.getService().getManagedSessions().values());

                session.write("COPY THAT.");
            }

        });
        try {
            acceptor.bind(new InetSocketAddress(5678));
        } catch (IOException e) {
            e.printStackTrace();
        }

        System.out.println("伺服器啟動成功，埠號5678...");
    }

    private static class MessageProtocolCodecFactory implements ProtocolCodecFactory {

        private final ProtocolEncoder encoder;
        private final ProtocolDecoder decoder;

        public MessageProtocolCodecFactory() {
            this(StandardCharsets.UTF_8);
        }

        public MessageProtocolCodecFactory(Charset charset) {
            this.encoder = new MessageProtocolEncoder(charset);
            this.decoder = new MessageProtocolDecoder(charset);
        }
        
        @Override
        public ProtocolEncoder getEncoder(IoSession session) throws Exception {
            return this.encoder;
        }

        @Override
        public ProtocolDecoder getDecoder(IoSession session) throws Exception {
            return this.decoder;
        }
    }

    private static class MessageProtocolDecoder extends CumulativeProtocolDecoder {

        private final CharsetDecoder charsetDecoder;

        public MessageProtocolDecoder(Charset charset) {
            this.charsetDecoder = charset.newDecoder();
        }

        @Override
        protected boolean doDecode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception {
            // Header部分四位元組，如果未接收完整，終止解析
            if (in.remaining() < 4) {
                return false;
            } else {
                in.mark();

                // 讀Header部資訊方式①
                // byte[] bytes = new byte[4];
                // in.get(bytes, 0, 4);
                // final int bodySize = convertByteArrayToInteger(bytes);

                // 讀Header部資訊方式②
                final int bodySize = in.getInt();

                // Body部分，如果未接收完整，終止解析
                if (in.remaining() < bodySize) {
                    in.reset();
                    return false;
                } else {
                    out.write(in.getString(bodySize, this.charsetDecoder));

                    return true;
                }
            }
        }

        private int convertByteArrayToInteger(byte[] bytes) {
            final int size = bytes.length;
            if (size > 4) {
                throw new IllegalArgumentException();
            }

            int result = 0;
            for (int i = 0; i < size; i++) {
                result += (bytes[i] & 0xFF) << ((size - 1 - i) * 8);
            }

            return result;
        }
    }

    private static class MessageProtocolEncoder implements ProtocolEncoder {

        private final CharsetEncoder charsetEncoder;

        public MessageProtocolEncoder(Charset charset) {
            this.charsetEncoder = charset.newEncoder();
        }

        @Override
        public void encode(IoSession session, Object message, ProtocolEncoderOutput out) throws Exception {
            final String msg = (String) message;
            final IoBuffer buf = IoBuffer.allocate(msg.length() + 4);

            // 寫Header部資訊方式①
            // buf.put(convertIntegerToByteArray(msg.length(), 4));

            // 寫Header部資訊方式②
            buf.putInt(msg.length());

            // 寫Body部資訊
            buf.putString(msg, this.charsetEncoder);
            buf.flip();
            out.write(buf);
        }

        @Override
        public void dispose(IoSession session) throws Exception {
            // do nothing
        }

        private byte[] convertIntegerToByteArray(int val, int length) {
            if (length > 4 || length < 1) {
                throw new IllegalArgumentException();
            }

            byte[] result = new byte[length];
            for (int i = 0; i < length; i++) {
                result[i] = (byte)((val >> ((length - 1 - i) * 8)) & 0xFF);
            }

            return result;
        }
    }

}