Golang中使用TCP发送多个文件时，如何解决文件合并的问题？

package main

import (
    "encoding/binary"
    "fmt"
    "io/ioutil"
    "log"
    "net"
    "os"
)

func main() {
    conn, err := net.Dial("tcp", ":9900")
    if err != nil {
        log.Fatalf("dial: %v", err)
    }
    defer conn.Close()

    files := []string{"./file/1.jpg", "./file/2.jpg"} // 需要发送的文件列表

    for _, file := range files {
        data, err := ioutil.ReadFile(file)
        if err != nil {
            log.Fatalf("read file %s: %v", file, err)
        }
        length := len(data)
        lengthBytes := make([]byte, 8)
        binary.BigEndian.PutUint64(lengthBytes, uint64(length)) // 将文件长度转换为8字节的big endian表示

        _, err = conn.Write(lengthBytes)
        if err != nil {
            log.Fatalf("write length: %v", err)
        }
        _, err = conn.Write(data)
        if err != nil {
            log.Fatalf("write data: %v", err)
        }
    }
}

package main

import (
    "encoding/binary"
    "fmt"
    "io"
    "log"
    "net"
    "os"
)

func main() {
    listener, err := net.Listen("tcp", ":9900")
    if err != nil {
        log.Fatalf("listen: %v", err)
    }
    defer listener.Close()

    for {
        conn, err := listener.Accept()
        if err != nil {
            log.Printf("accept: %v", err)
            continue
        }
        go handleConnection(conn)
    }
}

func handleConnection(conn net.Conn) {
    defer conn.Close()
    fileNum := 1
    for {
        lengthBytes := make([]byte, 8)
        _, err := io.ReadFull(conn, lengthBytes)
        if err == io.EOF {
            break
        }
        if err != nil {
            log.Printf("read length: %v", err)
            break
        }
        length := int(binary.BigEndian.Uint64(lengthBytes))
        fileName := fmt.Sprintf("./tmp/%d.jpg", fileNum)
        file, err := os.Create(fileName)
        if err != nil {
            log.Printf("create file %s: %v", fileName, err)
            break
        }
        defer file.Close()

        data := make([]byte, length)
        _, err = io.ReadFull(conn, data)
        if err != nil {
            log.Printf("read data: %v", err)
            break
        }
        _, err = file.Write(data)
        if err != nil {
            log.Printf("write data to file %s: %v", fileName, err)
            break
        }
        fmt.Printf("Received file %s\n", fileName)
        fileNum++
    }
}