1.本例子實現了一個簡單的TCP echo。客戶端發送Hello，服務端回應World。

參考：《Socket編程》

2.服務端代碼

package main

import (
    "net"
    "fmt"
    "os"
    "time"
)

//錯誤處理函數
func checkErr(err error, extra string) bool {
    if err != nil {
        formatStr := " Err : %s\n";
        if extra != "" {
            formatStr 
 
= extra + formatStr;
        }

        fmt.Fprintf(os.Stderr, formatStr, err.Error());
        return true;
    }

    return false;
}

//連接處理函數
func svrConnHandler(conn net.Conn) {
    fmt.Println("Client connect success :", conn.RemoteAddr().String());
    conn.SetReadDeadline(time.Now().Add(
 
2 * time.Minute))
    request := make([]byte, 128);
    defer conn.Close();
    for {
        readLen, err := conn.Read(request)
        if checkErr(err, "Read") {
            break;
        }

        //socket被關閉了
        if readLen == 0 {
            fmt.Println("Client connection close!");
            
 
break;
        } else {
            //輸出接收到的信息
            fmt.Println(string(request[:readLen]))

            time.Sleep(time.Second);
            //發送
            conn.Write([]byte("World !"));
        }

        request = make([]byte, 128);
    }
}

func main() {
    //解析地址
    tcpAddr, err := net.ResolveTCPAddr("tcp", "127.0.0.1:6666");
    if checkErr(err, "ResolveTCPAddr") {
        return;
    }

    //設置監聽地址
    listener, err := net.ListenTCP("tcp", tcpAddr);
    if checkErr(err, "ListenTCP") {
        return;
    }

    for {
        //監聽
        fmt.Println("Start wait for client.")
        conn, err := listener.Accept();
        if checkErr(err, "Accept") {
            continue;
        }

        //消息處理函數
        go svrConnHandler(conn);
    }
}

3.客戶端代碼

package main

import (
    "fmt"
    "os"
    "net"
    "sync"
)

var gLocker sync.Mutex; //全局鎖
var gCondition *sync.Cond; //全局條件變量

//錯誤處理函數
func checkErr(err error, extra string) bool {
    if err != nil {
        formatStr := " Err : %s\n";
        if extra != "" {
            formatStr = extra + formatStr;
        }

        fmt.Fprintf(os.Stderr, formatStr, err.Error());
        return true;
    }

    return false;
}

//連接處理函數
func clientConnHandler(conn net.Conn) {
    gLocker.Lock();
    defer gLocker.Unlock();

    defer conn.Close();

    request := make([]byte, 128);
    for {
        readLen, err := conn.Read(request)
        if checkErr(err, "Read") {
            gCondition.Signal();
            break;
        }

        //socket被關閉了
        if readLen == 0 {
            fmt.Println("Server connection close!");

            //條件變量同步通知
            gCondition.Signal();
            break;
        } else {
            //輸出接收到的信息
            fmt.Println(string(request[:readLen]))

            //發送
            conn.Write([]byte("Hello !"));
        }

        request = make([]byte, 128);
    }
}

func main() {
    //解析地址
    tcpAddr, err := net.ResolveTCPAddr("tcp", "127.0.0.1:6666");
    if checkErr(err, "ResolveTCPAddr") {
        return;
    }

    conn, err := net.DialTCP("tcp", nil, tcpAddr);
    if checkErr(err, "DialTCP") {
        return;
    }

    fmt.Println("Connect server success.")

    gLocker.Lock();
    gCondition = sync.NewCond(&gLocker);

    //發送數據給服務器
    conn.Write([]byte("Hello !"));

    //處理連接（lock在上面調用了，所以clientConnHandler函數必須等wait函數調用後才能lock,這樣就能保證調用的先後順序）
    go clientConnHandler(conn);

    //主線程阻塞，等待Singal結束
    for {
        //條件變量同步等待
        gCondition.Wait();
        break;
    }
    gLocker.Unlock();
    fmt.Println("Client finish.")
}

4.結果截圖

以上。

Golang socket