min-dev-java/src/main/java/component/Payload.java

package component;

import encoding.*;

/*
 * @Author: Wang Feng
 * @Description: 表示网络包负载
//	1. 格式如下：
//		Payload = PAYLOAD-TYPE TLV-LENGTH *OCTET
//	2. 详情参见：http://gitea.qjm253.cn/PKUSZ-future-network-lab/minlib/src/branch/master/docs/PacketFormat.md#4-signature
 * @Version: 1.0.0
 * @Date: 19:26 2021/3/9
 * @Copyright: MIN-Group；国家重大科技基础设施——未来网络北大实验室；深圳市信息论与未来网络重点实验室
 */
public class Payload implements TlvComponentBase,InitialAble, IEncodingAble {
    // 成员变量
    private byte[] value;

    public Payload(){
    }

    /**
     * 构造函数
     * @param block
     */
    public Payload(Block block){
        this.buildPayloadByBlock(block);
    }

    /**
     * 根据 TLV Block 初始化一个 Payload
     * @param block
     * @return
     */
    public boolean buildPayloadByBlock(Block block){
        return this.wireDecode(block);
    }

    /**
     * 得到Payload TLV中实际包含的数据
     * @return
     */
    public byte[] getValue() {
        return value;
    }

    /**
     * 设置 Payload TLV 中的Value
     * @param value
     */
    public void setValue(byte[] value) {
        this.value = value;
        this.doInitial();
    }

    // 接口实现-变量区
    private boolean initial=false;

    // 接口实现-方法区
    @Override
    public void doInitial() {
        initial=true;
    }

    @Override
    public boolean isInitial() {
        return initial;
    }

    /**
     * 将 Payload 线速编码为一个 TLV
     * @param encoder
     * @return
     */
    @Override
    public int wireEncode(Encoder encoder) throws ComponentException {
        try {
            int totalLength = 0;

            // 编码 TLV-VALUE
            int tmplen = encoder.prependByteArray(this.value, new SizeT(this.value.length));
            if (tmplen < 0) {
                return -1;
            }
            totalLength += tmplen;

            // 编码 TLV-LENGTH
            tmplen += encoder.prependVarNumber(new VlInt(totalLength));
            if (tmplen < 0) {
                return -1;
            }
            totalLength += tmplen;

            // 编码 TLV-TYPE
            tmplen += encoder.prependVarNumber(new VlInt(TLV.TlvPayload));
            if (tmplen < 0) {
                return -1;
            }
            totalLength += tmplen;

            return totalLength;
        } catch (EncoderException e) {
            throw new ComponentException("Payload.wireEncode: "+e.getMessage());
        }
    }

    @Override
    public boolean wireDecode(Block block) {
        // 检查 Type 是否正确
        if(!TLV.expectType(block.getType(),new VlInt(TLV.TlvPayload))){
            return false;
        }

        // 存储Value
        this.setValue(block.getValue());
        return true;
    }
}