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using System;
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using System.Text;
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/**
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* Created by Tong on 2021/9/22.
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* link协议粘包拆包
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*/
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public class LinkMessageDecoder
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{
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//instance
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private static LinkMessageDecoder instance = new LinkMessageDecoder();
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//getInstance
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public static LinkMessageDecoder getInstance()
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{
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return instance;
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}
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/**
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* 接收数据缓冲区
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*/
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private byte[] byteBuffer;
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private int position;
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private byte[] head = System.Text.Encoding.UTF8.GetBytes("Topic:");
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public LinkMessageDecoder()
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{
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byteBuffer = new byte[1024 * 20];//100K
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}
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/// <summary>
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/// 获取内容长度
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/// </summary>
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/// <param name="topMsgs"></param>
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/// <returns></returns>
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private int getLenght(string[] topMsgs)
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{
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try
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{
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for (int i = 0; i < topMsgs.Length; i++)
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{
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string topMsg = topMsgs[i].Trim();
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if (topMsg.StartsWith("Length:"))
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{
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return int.Parse(topMsg.Replace("Length:", "").Trim());
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}
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}
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}
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catch (Exception e)
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{
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//LogUtils.e("异常数据：" + topMsgs[0] + "\r\n" + topMsgs[1]);
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return -1;
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}
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//找不到长度
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return -1;
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}
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/// <summary>
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/// 获取主题
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/// </summary>
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/// <param name="topMsgs"></param>
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/// <returns></returns>
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private string getTopic(string[] topMsgs)
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{
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for (int i = 0; i < topMsgs.Length; i++)
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{
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string topMsg = topMsgs[i].Trim();
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if (topMsg.StartsWith("Topic:"))
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{
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return topMsg.Replace("Topic:", "");
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}
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}
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//找不到主题
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return null;
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}
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/**
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* 获取数据的开始位置
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*
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* @return 数据位的开始索引
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*/
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private int getBodyIndex()
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{
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byte r = (byte)'\r';
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byte n = (byte)'\n';
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for (int i = 0; i < position; i++)
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{
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//找出数据内容前面的两个换行
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if (3 <= i && byteBuffer[i - 3] == r && byteBuffer[i - 2] == n && byteBuffer[i - 1] == r && byteBuffer[i] == n)
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{
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//剩余的数据
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return i + 1;
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}
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}
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return -1;
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}
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/**
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* 获取头部数据
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*
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* @return
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*/
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private string getHeader()
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{
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int bodyIndex = getBodyIndex();
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if (bodyIndex < 0)
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{
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//没有找到头部数据
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return null;
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}
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else
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{
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return System.Text.Encoding.UTF8.GetString(byteBuffer, 0, bodyIndex);
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}
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}
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/**
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* 获取数据内容
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*
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* @param lenght
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* @return
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*/
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private byte[] getBody(int index, int lenght)
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{
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//是否已经获取完整所有的数据
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byte[] bodyBytes = new byte[lenght];
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if (index < 0 || position < index + lenght)
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{
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//当前数据还没有接收完成
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return null;
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}
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for (int i = 0; i < bodyBytes.Length; i++)
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{
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bodyBytes[i] = byteBuffer[index + i];
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}
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return bodyBytes;
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}
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/**
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* 移除可能存在的无效数据
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*/
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private void removeInVoidBytes()
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{
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int index = 0;
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bool isMatch = false;
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for (; index < position - head.Length; index++)
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{
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isMatch = true;
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for (int j = 0, k = 0; j < head.Length; j++, k++)
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{
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if (head[j] != byteBuffer[index + k])
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{
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isMatch = false;
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break;
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}
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}
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if (isMatch)
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{
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break;
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}
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}
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if (0 < index && isMatch)
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{
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int endIndex = position;
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position = 0;
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//byteBuffer.clear();
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for (int i = index; i < endIndex; i++)
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{
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byteBuffer[position++] = byteBuffer[i];
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}
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}
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}
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/**
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* 移除到指定位置前面的数据
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*
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* @param position 指定位置
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*/
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private void remove(int index)
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{
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int endIndex = position;
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position = 0;
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//byteBuffer.clear();
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for (int i = index; i < endIndex; i++)
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{
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byteBuffer[position++] = byteBuffer[i];
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}
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}
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public void Decoder(byte[] bytes, Action<string, byte[]> action)
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{
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lock (instance)
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{
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try
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{
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if (null == bytes)
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{
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return;
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}
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System.Array.Copy(bytes, 0, byteBuffer, position, bytes.Length);
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position += bytes.Length;
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//如果多条命令打包在一条数据中，都需要处理完
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while (true)
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{
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removeInVoidBytes();//移除可能存在的无效数据
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//头部数据
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string header = getHeader();
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if (header == null)
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{
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break;
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}
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string[] topMsgs = header.Split("\r\n");
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string topic = getTopic(topMsgs);
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int lenght = getLenght(topMsgs);
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if (topic == null || lenght <= 0)
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{
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//获取不到主题或者头部数据还没有接收完成
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break;
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}
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int bodyIndex = getBodyIndex();
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//是否已经获取完整所有的数据
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byte[] body = getBody(bodyIndex, lenght);
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if (body == null)
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{
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//当前数据还没有接收完成
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break;
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}
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remove(bodyIndex + lenght);
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action?.Invoke(topic, body);
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}
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}
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catch (Exception ee)
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{
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}
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}
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}
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}
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