【MinaFile】【三】写自定义编码解码

来源：互联网发布：局域网域名编辑：程序博客网时间：2024/06/05 16:47

一、添加常量类Constants

/** * 消息自身字节常量类 * @author king_fu * */public class Constants {    public static final int TYPE_LEN = 2;    public static final int SEQUENCE_LEN = 4;    public static final int HEADER_LEN = TYPE_LEN + SEQUENCE_LEN;    public static final int BODY_LEN = 12;    public static final int RESULT = 0;    public static final int ADD = 1;    public static final int RESULT_CODE_LEN = 2;    public static final int RESULT_VALUE_LEN = 4;    public static final int ADD_BODY_LEN = 4;    public static final int RESULT_OK = 0;    public static final int RESULT_ERROR = 1;    private Constants() {    }}

下面用了设计模式中的模版方法。

二、添加抽象父类解码器AbstractMessageDecoder

/** * 父类解码 * @author king_fu * */public abstract class AbstractMessageDecoder implements MessageDecoder {    private final int type;    private int sequence;    private boolean readHeader;    protected AbstractMessageDecoder(int type) {        this.type = type;    }    public MessageDecoderResult decodable(IoSession session, IoBuffer in) {    // 判断是否符合最小的头长度。一个short+一个int类型。    /**     *  // 编码头         *    buf.putShort((short) type);         *     buf.putInt(message.getSequence());     */        if (in.remaining() < Constants.HEADER_LEN) {            return MessageDecoderResult.NEED_DATA;        }        if (type == in.getShort()) {            return MessageDecoderResult.OK;        }        return MessageDecoderResult.NOT_OK;    }    public MessageDecoderResult decode(IoSession session, IoBuffer in,            ProtocolDecoderOutput out) throws Exception {                 if (!readHeader) {            in.getShort();              sequence = in.getInt();             readHeader = true;        }        AbstractMessage m = decodeBody(session, in);        if (m == null) {            return MessageDecoderResult.NEED_DATA;        } else {            readHeader = false;          }        m.setSequence(sequence);        out.write(m);        return MessageDecoderResult.OK;    }      /**     * 模版方法     * @param session 当前的session     * @param in 输入流     * @return如果对象没有读完返回null     */    protected abstract AbstractMessage decodeBody(IoSession session,            IoBuffer in);}

三、添加抽象父类编码器AbstractMessageDecoder

/** * 父类编码 * @author king_fu * * @param <T> */public abstract class AbstractMessageEncoder<T extends AbstractMessage> implements MessageEncoder<T> {    private final int type;    protected AbstractMessageEncoder(int type) {        this.type = type;    }    public void encode(IoSession session, T message, ProtocolEncoderOutput out) throws Exception {        IoBuffer buf = IoBuffer.allocate(16);        buf.setAutoExpand(true);         // 编码头        buf.putShort((short) type);        buf.putInt(message.getSequence());        // 编码体        encodeBody(session, message, buf);        buf.flip();        out.write(buf);    }    protected abstract void encodeBody(IoSession session, T message, IoBuffer out);}

四、添加子类解码器MessageDecoder

/** * 消息解码 * @author king_fu * */public class MessageDecoder extends AbstractMessageDecoder {    public MessageDecoder() {        super(Constants.ADD);    }    @Override    protected AbstractMessage decodeBody(IoSession session, IoBuffer in) {        if (in.remaining() < Constants.ADD_BODY_LEN) {            return null;        }        Message m = new Message();        m.setValue(in.getInt());        return m;    }    public void finishDecode(IoSession session, ProtocolDecoderOutput out)            throws Exception {    }}

五、添加子类编码器MessageEncoder

/** * 消息编码 * @author king_fu * * @param <T> */public class MessageEncoder<T extends Message> extends AbstractMessageEncoder<T> {    public MessageEncoder() {        super(Constants.ADD);    }    @Override    protected void encodeBody(IoSession session, T message, IoBuffer out) {        out.putInt(message.getValue());    }    public void dispose() throws Exception {    }}

六、添加子类解码器ResultMessageDecoder

/** * 返回的消息解码 * @author king_fu * */public class ResultMessageDecoder extends AbstractMessageDecoder {    private int code;    private boolean readCode;    public ResultMessageDecoder() {        super(Constants.RESULT);    }    @Override    protected AbstractMessage decodeBody(IoSession session, IoBuffer in) {        if (!readCode) {            if (in.remaining() < Constants.RESULT_CODE_LEN) {                return null;             }            code = in.getShort();            readCode = true;        }        if (code == Constants.RESULT_OK) {            if (in.remaining() < Constants.RESULT_VALUE_LEN) {                return null;            }            ResultMessage m = new ResultMessage();            m.setOk(true);            m.setValue(in.getInt());            readCode = false;            return m;        } else {            ResultMessage m = new ResultMessage();            m.setOk(false);            readCode = false;            return m;        }    }    public void finishDecode(IoSession session, ProtocolDecoderOutput out)            throws Exception {    }}

七、添加子类编码器ResultMessageEncoder

/** * 返回的消息编码 * @author king_fu * * @param <T> */public class ResultMessageEncoder<T extends ResultMessage> extends AbstractMessageEncoder<T> {    public ResultMessageEncoder() {        super(Constants.RESULT);    }    @Override    protected void encodeBody(IoSession session, T message, IoBuffer out) {        if (message.isOk()) {            out.putShort((short) Constants.RESULT_OK);            out.putInt(message.getValue());        } else {            out.putShort((short) Constants.RESULT_ERROR);        }    }    public void dispose() throws Exception {    }}

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