在移动通信领域，短信（Short Message Service，简称SMS）是一种非常基础的通信方式。短信的数据传输是通过特定的格式来实现的，这种格式被称为PDU（Protocol Data Unit，协议数据单元）。理解短信PDU结构对于开发者来说至关重要，因为它可以帮助我们更好地读取和发送短信。本文将带领大家轻松掌握短信PDU的结构，并学习如何解码这些数据。
什么是短信PDU？
短信PDU是一种用于移动通信网络中的数据传输格式。它包含了短信的所有信息，包括发送者、接收者、短信内容、编码方式等。PDU数据通常以16进制的形式表示。
短信PDU结构解析
一个典型的短信PDU结构如下：
PDU Header | TPDU (Teleservice Data Unit)
PDU Header
PDU Header包含了短信的一些基本属性，如协议标识、信息类型、编码方式等。以下是PDU Header的一些关键字段：
- Protocol Identifier (PID): 协议标识，用于指示PDU的类型，如0x01表示短信。
- Data Coding Scheme (DCS): 数据编码方案，用于指定短信内容的编码方式，如0x00表示7位ASCII编码，0x08表示UCS2编码。
- Message Type (MT): 信息类型，用于指示短信是发送、接收还是其他类型。
TPDU (Teleservice Data Unit)
TPDU包含了短信的具体内容，包括发送者、接收者、短信正文等。以下是TPDU的一些关键字段：
- Service Center Address (SCA): 服务中心地址，用于指示短信发送或接收的服务中心。
- Destination Address (DA): 目标地址，即接收短信的号码。
- Originating Address (OA): 发送者地址，即发送短信的号码。
- User Data Header (UDH): 用户数据头，用于携带一些附加信息，如短信优先级、短信类别等。
- User Data (UD): 用户数据，即短信正文。
短信PDU解码示例
以下是一个简单的短信PDU解码示例：
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