一个Rust实现的mqtt协议解析库
rust
let connect = MqttMessageBuilder::connect()
.client_id("client_01")
.keep_alive(10)
.clean_session(true)
.username("rump")
.password("mq")
.protocol_level(crate::MqttVersion::V4)
.retain(false)
.will_qos(crate::QoS::AtLeastOnce)
.will_topic("/a")
.will_message(Bytes::from_static(b"offline"))
.build().unwarp();
MqttMessageBuilder: 是MQTT报文的构建器，提供了多种MQTT报文的构建方式。
MqttMessageBuilder并没有具体的属性，MqttMessageBuilder提供了其他具体Builder的方法,例如：
rust
pub fn connect() -> ConnectBuilder {
ConnectBuilder::new()
}
```rust
/// 编码
pub trait Encoder: Sync + Send + 'static {
fn encode(&self, buffer: &mut BytesMut) -> Result
/// 解码
pub trait Decoder: Sync + Send + 'static {
// 定义的返回类型
type Item;
type Error;
// 将bytes解析为对应的报文
fn decode(bytes: Bytes) -> Result
Encoder和Decoder实现了Bytes和Mqtt报文的相互转换,每种MQTT报文类型都实现了Encoder和Decoder，以Connect报文为例：
rust
fn encodeanddecodeforconnectshouldbework() {
let connect = buildconnect().unwrap();
println!("原始connect = {:?}", connect);
let mut bytes = BytesMut::new();
let mut bytes1 = BytesMut::new();
// encoder
connect.encode(&mut bytes).unwrap();
println!("bytes = {:?}", bytes);
let connect1 = Connect::decode(bytes.freeze());
match connect1 {
Ok(connect) => {
println!("connect1 = {:?}", connect);
connect.encode(&mut bytes1).unwrap();
println!(
"encodeanddecodeforconnectshoudbe_work bytes1 = {:?}",
bytes1
);
// decoder
let connect2 = Connect::decode(bytes1into()).unwrap();
println!("connect2 = {:?}", connect2);
}
Err(err) => println!("编解码出错"),
}
}
```