go语言渐入佳境-网络[5]-tcpaddr

TCPAddr

type TCPAddr struct {
IP IP
Port int
}

ResolveTCPAddr函数用于创建TCPAddr

func ResolveTCPAddr(net, addr string) (*TCPAddr, os.Error)

其中参数net是“tcp”，“tcp4”或“tcp6”之一，addr是由主机名或IP地址组成的字符串，后跟“：”后面的端口号，例如“www.google.com:80“或”127.0.0.1:22“。

func DialTCP(net string, laddr, raddr *TCPAddr) (c *TCPConn, err os.Error)

func (c *TCPConn) SetTimeout(nsec int64) os.Error
即使客户端无需发送任何内容，客户端也可能希望保持与服务器的连接。它可以使用:
func (c *TCPConn) SetKeepAlive(keepalive bool) os.Error

func (c *TCPConn) Write(b []byte) (n int, err os.Error)
func (c *TCPConn) Read(b []byte) (n int, err os.Error)

客户端

/* GetHeadInfo
 */
package main

import (
	"net"
	"os"
	"fmt"
	"io/ioutil"
)

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]

  // 生成TCPAddr
	tcpAddr, err := net.ResolveTCPAddr("tcp4", service)
	checkError(err)

  // 创建网络连接
	conn, err := net.DialTCP("tcp", nil, tcpAddr)
	checkError(err)

  // 写数据
	_, err = conn.Write([]byte("HEAD / HTTP/1.0\r\n\r\n"))
	checkError(err)

  // 读数据
	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)
	}
}

测试

$ ./net www.baidu.com:80
HTTP/1.0 302 Found
Content-Length: 17931
Content-Type: text/html
Date: Fri, 18 Jan 2019 15:33:50 GMT
Etag: "54d9748e-460b"
Server: bfe/1.0.8.18

服务器

func ListenTCP(net string, laddr *TCPAddr) (l *TCPListener, err os.Error)
func (l *TCPListener) Accept() (c Conn, err os.Error)

ListenTCP为服务器监听端口，Accept代表锁住，等待客户端连接

/* DaytimeServer
 */
package main

import (
    "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
        }

        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)
    }
}

多线程服务器

/* ThreadedEchoServer
 */
package main

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

func main() {

    service := ":1201"
    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
        }
        // run as a goroutine
        go handleClient(conn)
    }
}

func handleClient(conn net.Conn) {
    // close connection on exit
    defer conn.Close()

    var buf [512]byte
    for {
        // read upto 512 bytes
        n, err := conn.Read(buf[0:])
        if err != nil {
            return
        }

        // write the n bytes read
        _, err2 := conn.Write(buf[0:n])
        if err2 != nil {
            return
        }
    }
}

func checkError(err error) {
    if err != nil {
        fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())
        os.Exit(1)
    }
}