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Golang有自己的序列化格式,称为gob。使用gob可以对结构进行编码和解码。你可以使用其他格式,如JSON, XML, protobuff等,具体选择要根据实际需求,但当接收和发送都为Golang,我建议使用Go的gob格式。
Gob简介
gob在kg/encoding/gob包中:
gob流是自描述的,这意味着我们不需要创建单独的文件来解释(使用protobuff格式需要创建文件)
gob流中的每个数据项之前都有其类型说明(一些预定义的类型)
Gob包很简单,仅包括8个函数和5个类型:
func Register(value interface{}) func RegisterName(name string, value interface{}) type CommonType type Decoder func NewDecoder(r io.Reader) *Decoder func (dec *Decoder) Decode(e interface{}) error func (dec *Decoder) DecodeValue(v reflect.Value) error type Encoder func NewEncoder(w io.Writer) *Encoder func (enc *Encoder) Encode(e interface{}) error func (enc *Encoder) EncodeValue(value reflect.Value) error type GobDecoder type GobEncoder
单个对象序列化
首先定义student结构体,包括两个字段Name和Age.
使用gob.NewEncoder和gob.NewDecoder方法,接收io.Writer 和 io.Reader 对象,用于读写文件:
package main import ( "fmt" "os" "encoding/gob" ) type Student struct { Name string Age int32 } func main() { fmt.Println("Gob Example") student := Student{"Ketan Parmar",35} err := writeGob("./student.gob",student) if err != nil{ fmt.Println(err) } var studentRead = new (Student) err = readGob("./student.gob",studentRead) if err != nil { fmt.Println(err) } else { fmt.Println(studentRead.Name, " ", studentRead.Age) } } func writeGob(filePath string,object interface{}) error { file, err := os.Create(filePath) if err == nil { encoder := gob.NewEncoder(file) encoder.Encode(object) } file.Close() return err } func readGob(filePath string,object interface{}) error { file, err := os.Open(filePath) if err == nil { decoder := gob.NewDecoder(file) err = decoder.Decode(object) } file.Close() return err }
列表数据序列化
首先创建student结构体数组或slice,然后填充数据。下面示例无需修改readGob和writeGob函数:
package main import ( "fmt" "os" "encoding/gob" ) type Student struct { Name string Age int32 } type Students []Student func main() { fmt.Println("Gob Example") students := Students{} students = append(students,Student{"Student 1",20}) students = append(students,Student{"Student 2",25}) students = append(students,Student{"Student 3",30}) err := writeGob("./student.gob",students) if err != nil{ fmt.Println(err) } var studentRead = new (Students) err = readGob("./student.gob",studentRead) if err != nil { fmt.Println(err) } else { for _,v := range *studentRead{ fmt.Println(v.Name, " ", v.Age) } } }
上面两个示例主要使用了NewEncoder 和 NewDecoder,接下来看看其他函数:Register, Encode, EncodeValue, Decode 和 DecodeValue。
Encode 和 Decode 函数主要用于网络应用程序,方法签名如下:
func (dec *Decoder) Decode(e interface{}) error
func (enc *Encoder) Encode(e interface{}) error
简单编码示例
package main import ( "fmt" "encoding/gob" "bytes" ) type Student struct { Name string Age int32 } func main() { fmt.Println("Gob Example") studentEncode := Student{Name:"Ketan",Age:30} var b bytes.Buffer e := gob.NewEncoder(&b) if err := e.Encode(studentEncode); err != nil { panic(err) } fmt.Println("Encoded Struct ", b) var studentDecode Student d := gob.NewDecoder(&b) if err := d.Decode(&studentDecode); err != nil { panic(err) } fmt.Println("Decoded Struct ", studentDecode.Name," ",studentDecode.Age) }
上面示例把student结构序列化、反序列化。序列化后存储在字节buffer变量b中,先可以使用b在网络中传输。要解码仅需要创建相同结构对象并提供其地址。studentDecode变量获得解码的内容。
编码在TCP连接中使用
TCP客户端:打开连接使用gob.Encoder方法编码数据进行传输:
package main import ( "fmt" "encoding/gob" "net" "log" ) type Student struct { Name string Age int32 } func main() { fmt.Println("Client") //create structure object studentEncode := Student{Name:"Ketan",Age:30} fmt.Println("start client"); // dial TCP connection conn, err := net.Dial("tcp", "localhost:8080") if err != nil { log.Fatal("Connection error", err) } //Create encoder object, We are passing connection object in Encoder encoder := gob.NewEncoder(conn) // Encode Structure, IT will pass student object over TCP connection encoder.Encode(studentEncode) // close connection conn.Close() fmt.Println("done"); }
TCP Server: 监听8080端口,在go协程中处理所有客户端,使用gob.Decoder方法解码student结构体并输出:
package main import ( "fmt" "net" "encoding/gob" ) type Student struct { Name string Age int32 } func handleConnection(conn net.Conn) { // create new decoder object and provide connection dec := gob.NewDecoder(conn) // create blank student object p := &Student{} // decode serialize data dec.Decode(p) // print fmt.Println("Hello ",p.Name,", Your Age is ",p.Age); // close connection for that client conn.Close() } func main() { fmt.Println("Server") // start TCP server and listen on port 8080 ln, err := net.Listen("tcp", ":8080") if err != nil { // handle error panic(err) } for { // this blocks until connection or error conn, err := ln.Accept() if err != nil { // handle error continue } // a goroutine handles conn so that the loop can accept other connections go handleConnection(conn) } }
上文中没有实现序列化,本文给出golang-ttl-map实现:
func (h *Heap) append(data Data) (err error) { h.fileMx.Lock() defer h.fileMx.Unlock() // 打开文件 var file *os.File file, err = os.OpenFile(h.filePath, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0755) if err != nil { return } defer func() { _ = file.Sync() }() defer func() { _ = file.Close() }() // 定义buffer var buf bytes.Buffer enc := gob.NewEncoder(&buf) // 序列化 err = enc.Encode(data) if err != nil { return } bs := buf.Bytes() bs = append(bs, ' ') // 写入文件 _, err = file.Write(bs) if err != nil { return } return }