在GO的net包中定义了很多对网络编程操作的方法.

比如操作IP,输入IP格式地址,返回IP

package mainimport (	"net"	"os"	"fmt")func main() {	if len(os.Args) != 2 {		fmt.Fprintf(os.Stderr, "Usage: %s ip-addr\n", os.Args[0])		os.Exit(1)	}	name := os.Args[1]	addr := net.ParseIP(name)	if addr == nil {		fmt.Println("Invalid address")	} else {		fmt.Println("The address is ", addr.String())	}	os.Exit(0)}

客户端代码

package mainimport (	"fmt"	"io/ioutil"	"net"	"os")func main() {	if len(os.Args) != 2 {		fmt.Fprintf(os.Stderr, "Usage: %s host:port ", os.Args[0])		os.Exit(1)	}	service := os.Args[1]	tcpAddr, err := net.ResolveTCPAddr("tcp4", service)  //获取一个IP地址转成格式	checkError(err)	conn, err := net.DialTCP("tcp", nil, tcpAddr)   //连接服务器,协议,本机地址,目的地址,本机地址一般为nil	checkError(err)	_, err = conn.Write([]byte("HEAD / HTTP/1.0\r\n\r\n"))   //请求头写进去,协议格式要把换行写清楚	checkError(err)	result, err := ioutil.ReadAll(conn)	checkError(err)	fmt.Println(string(result))	os.Exit(0)}func checkError(err error) {	if err != nil {		fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())		os.Exit(1)	}}

然后是tcp服务端

package mainimport (	"fmt"	"net"	"os"	"time")func main() {	service := ":7777"	tcpAddr, err := net.ResolveTCPAddr("tcp4", service)   //转换IP地址格式	checkError(err)	listener, err := net.ListenTCP("tcp", tcpAddr)  //监听端口	checkError(err)	for {		conn, err := listener.Accept()   //等等连接		if err != nil {			continue		}		daytime := time.Now().String()		conn.Write([]byte(daytime)) // don't care about return value		conn.Close()                // we're finished with this client	}}func checkError(err error) {	if err != nil {		fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())		os.Exit(1)	}}

然后是加了goroutine的服务端

package mainimport (	"fmt"	"net"	"os"	"time")func main() {	service := ":1200"	tcpAddr, err := net.ResolveTCPAddr("tcp4", service)	checkError(err)	listener, err := net.ListenTCP("tcp", tcpAddr)	checkError(err)	for {		conn, err := listener.Accept()		if err != nil {			continue		}		go handleClient(conn)   //每次有用户连接就启动一个单独的goroutine来处理,可以处理多用户,彼此保持独立性.	}}func handleClient(conn net.Conn) {	defer conn.Close()            //结束完后关闭连接,就是关闭用户的套接字.	daytime := time.Now().String()	conn.Write([]byte(daytime)) // don't care about return value	// we're finished with this client}func checkError(err error) {	if err != nil {		fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())		os.Exit(1)	}}

加个长连接,判断超时

package mainimport (	"fmt"	"net"	"os"	"time"	"strconv"	"strings")func main() {	service := ":1200"	tcpAddr, err := net.ResolveTCPAddr("tcp4", service)	checkError(err)	listener, err := net.ListenTCP("tcp", tcpAddr)	checkError(err)	for {		conn, err := listener.Accept()		if err != nil {			continue		}		go handleClient(conn)	}}func handleClient(conn net.Conn) {	conn.SetReadDeadline(time.Now().Add(2 * time.Minute)) // set 2 minutes timeout	request := make([]byte, 128) // set maxium request length to 128B to prevent flood attack	defer conn.Close()  // close connection before exit	for {		read_len, err := conn.Read(request)  //读取连接用户发送过来的内容,括号中为大小		if err != nil {			fmt.Println(err)			break		}    		if read_len == 0 {    			break // connection already closed by client    		} else if strings.TrimSpace(string(request[:read_len])) == "timestamp" {    			daytime := strconv.FormatInt(time.Now().Unix(), 10)    			conn.Write([]byte(daytime))    		} else {    			daytime := time.Now().String()    			conn.Write([]byte(daytime))    		}    		request = make([]byte, 128) //清除内容,开始下一次	}}func checkError(err error) {	if err != nil {		fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())		os.Exit(1)	}}

再就是UDP客户端

package mainimport (	"fmt"	"net"	"os")func main() {	if len(os.Args) != 2 {		fmt.Fprintf(os.Stderr, "Usage: %s host:port", os.Args[0])		os.Exit(1)	}	service := os.Args[1]	udpAddr, err := net.ResolveUDPAddr("udp4", service)  //转换IP地址	checkError(err)	conn, err := net.DialUDP("udp", nil, udpAddr)   //UDP连接	checkError(err)	_, err = conn.Write([]byte("anything"))  //发送内容	checkError(err)	var buf [512]byte	n, err := conn.Read(buf[0:])   //读取响应内容	checkError(err)	fmt.Println(string(buf[0:n]))	os.Exit(0)}func checkError(err error) {	if err != nil {		fmt.Fprintf(os.Stderr, "Fatal error ", err.Error())		os.Exit(1)	}}

udp服务器

package mainimport (	"fmt"	"net"	"os"	"time")func main() {	service := ":1200"	udpAddr, err := net.ResolveUDPAddr("udp4", service)   //转换IP地址格式	checkError(err)	conn, err := net.ListenUDP("udp", udpAddr)   //监听IP和地址	checkError(err)	for {		handleClient(conn)	}}func handleClient(conn *net.UDPConn) {	var buf [512]byte	_, addr, err := conn.ReadFromUDP(buf[0:])   //读取接收的内容	if err != nil {		return	}	daytime := time.Now().String()	conn.WriteToUDP([]byte(daytime), addr)   //回复内容}func checkError(err error) {	if err != nil {		fmt.Fprintf(os.Stderr, "Fatal error ", err.Error())		os.Exit(1)	}}