go smtp示例
书接上文
telnet smtp.163.com 25 [outpout] ehlo dz45693 [outpout] auth login [outpout] 输入用户名base64 [outpout] 输入密码base64 mail from:<dz45693@163.com> [outpout] rcpt to:<dz45693@sina.com> [outpout] data [outpout] from:<dz45693@163.com> to:<dz45693@sina.com> subject:hello world This is the first email sent by hand using the SMTP protocol . quit
好，那我们下现在用go实现代码让如下： 这里只是一个demo，主要熟悉smtp命令
package main import ( "bufio" "encoding/base64" "fmt" "net" "strconv" "strings" ) func main() { testSmtp() } var gConn net.Conn var gRead *bufio.Reader var gWrite *bufio.Writer //可以放到这样的类里 type TcpClient struct { Conn net.Conn Read *bufio.Reader Write *bufio.Writer } // func Connect(host string, port int) (net.Conn, *bufio.Reader, *bufio.Writer) { addr := host + ":" + strconv.Itoa(port) conn, err := net.Dial("tcp", addr) if err != nil { return nil, nil, nil } reader := bufio.NewReader(conn) writer := bufio.NewWriter(conn) return conn, reader, writer } // //收取一行,可再优化 func RecvLine() string { line, err := gRead.ReadString('\n') //如何设定超时? if err != nil { fmt.Print(err) return "" } line = strings.Split(line, "\r")[0] //还要再去掉 "\r"，其实不去掉也可以 return line } func SendLine(line string) { gWrite.WriteString(line + "\r\n") gWrite.Flush() } //解码一行命令,这里比较简单就是按空格进行分隔就行了 func DecodeCmd(line string, sp string) []string { tmp := strings.Split(line, sp) var cmds = []string{"", "", "", "", ""} //先定义多几个，以面后面使用时产生异常 for i := 0; i < len(tmp); i++ { if i >= len(cmds) { break } cmds[i] = tmp[i] } return cmds } //读取多行结果 func RecvMCmd() string { i := 0 rs := "" mLine := "" for i = 0; i < 50; i++ { rs = RecvLine() //只收取一行 mLine = mLine + rs + "\r\n" if len(rs) < 4 { break } //长度要足够 c4 := rs[4-1] //第4个字符 if ' ' == c4 { break } //第4个字符是空格就表示读取完了//也可以判断 "250[空格]" } return mLine } //简单的测试一下 smtp func testSmtp() { //连接 gConn, gRead, gWrite = Connect("smtp.163.com", 25) defer gConn.Close() //收取一行 line := RecvLine() fmt.Println("recv:" + line) //解码一下,这样后面的 EHLO 才能有正确的第二个参数 cmds := DecodeCmd(line, " ") domain := cmds[1] //要从对方的应答中取出域名//空格分开的各个命令参数中的第二个 //发送一个命令 SendLine("EHLO" + " " + domain) //domain 要求其实来自 HELO 命令//HELO <SP> <domain> <CRLF> //收取多行 line = RecvMCmd() fmt.Println("recv:" + line) //-------------------------------------------------- //用 base64 登录 SendLine("AUTH LOGIN") //收取一行 line = RecvLine() fmt.Println("recv:" + line) s := "dz45693" //要换成你的用户名,注意 163 邮箱的话不要带后面的 @域名 部分 s = base64.StdEncoding.EncodeToString([]byte(s)) SendLine(s) //收取一行 line = RecvLine() fmt.Println("recv:" + line) s = "xxxxx" //要换成您的密码 s = base64.StdEncoding.EncodeToString([]byte(s)) SendLine(s) //收取一行 line = RecvLine() fmt.Println("recv:" + line) //-------------------------------------------------- //邮件内容 from := "dz45693@163.com" to := "dz45693@sina.com" SendLine("MAIL FROM: <" + from + ">") //注意"<" 符号和前面的空格。空格在协议中有和没有都可能，最好还是有 //收取一行 line = RecvLine() fmt.Println("recv:" + line) SendLine("RCPT TO: <" + to + ">") //收取一行 line = RecvLine() fmt.Println("recv:" + line) SendLine("DATA") //收取一行 line = RecvLine() fmt.Println("recv:" + line) //发送邮件头 SendLine("from:<dz45693@163.com>") SendLine("to:<dz45693@sina.com>") SendLine("subject:hello world") SendLine("") //发送空行 后面就是邮件体 SendLine("This is the first email sent by hand using the SMTP protocol") SendLine(".") //邮件结束符 //收取一行 line = RecvLine() fmt.Println("recv:" + line) SendLine("quit") //链接推出 line = RecvLine() fmt.Println("recv:" + line) } //
运行结果图下：
在go的sdk中提供了SendMail方法【发送邮件后这个方法会关闭链接】，实现如下：
实现如下：
func SendMailBySmtp(){ auth := smtp.PlainAuth("", "dz45693@163.com", "xxx", "smtp.163.com") to := []string{"dz45693@sina.com"} image,_:=ioutil.ReadFile("d:\\Downloads\\1.png") imageBase64:=base64.StdEncoding.EncodeToString(image) msg := []byte("from:dz45693@163.com\r\n"+ "to: dz45693@sina.com\r\n" + "Subject: hello,subject!\r\n"+ "Content-Type:multipart/mixed;boundary=a\r\n"+ "Mime-Version:1.0\r\n"+ "\r\n" + "--a\r\n"+ "Content-type:text/plain;charset=utf-8\r\n"+ "Content-Transfer-Encoding:quoted-printable\r\n"+ "\r\n"+ "此处为正文内容!\r\n"+ "--a\r\n"+ "Content-type:image/jpg;name=1.jpg\r\n"+ "Content-Transfer-Encoding:base64\r\n"+ "\r\n"+ imageBase64+"\r\n"+ "--a--\r\n") err := smtp.SendMail("smtp.163.com:25", auth, "dz45693@163.com", to, msg) if err != nil { fmt.Println(err) } }
运行效果
示例如下：
func SendMailByGomailOne(){ m := gomail.NewMessage() m.SetAddressHeader("From", "dz45693@163.com", "dz45693") m.SetHeader("To", "dz45693@sina.com") m.SetHeader("Subject", "hello SendMailByGomailOne!") m.Embed("d:\\Downloads\\1.png") m.SetBody("text/html", "此处为正文121333!") d := gomail.NewDialer("smtp.163.com", 25, "dz45693@163.com", "xxxx#") if err := d.DialAndSend(m); err != nil { panic(err) } }
运行结果：
来我们看看DialAndSend的实现如下：
package gomail import ( "crypto/tls" "fmt" "io" "net" "net/smtp" "strings" "time" ) // A Dialer is a dialer to an SMTP server. type Dialer struct { // Host represents the host of the SMTP server. Host string // Port represents the port of the SMTP server. Port int // Username is the username to use to authenticate to the SMTP server. Username string // Password is the password to use to authenticate to the SMTP server. Password string // Auth represents the authentication mechanism used to authenticate to the // SMTP server. Auth smtp.Auth // SSL defines whether an SSL connection is used. It should be false in // most cases since the authentication mechanism should use the STARTTLS // extension instead. SSL bool // TSLConfig represents the TLS configuration used for the TLS (when the // STARTTLS extension is used) or SSL connection. TLSConfig *tls.Config // LocalName is the hostname sent to the SMTP server with the HELO command. // By default, "localhost" is sent. LocalName string } // NewDialer returns a new SMTP Dialer. The given parameters are used to connect // to the SMTP server. func NewDialer(host string, port int, username, password string) *Dialer { return &Dialer{ Host: host, Port: port, Username: username, Password: password, SSL: port == 465, } } // NewPlainDialer returns a new SMTP Dialer. The given parameters are used to // connect to the SMTP server. // // Deprecated: Use NewDialer instead. func NewPlainDialer(host string, port int, username, password string) *Dialer { return NewDialer(host, port, username, password) } // Dial dials and authenticates to an SMTP server. The returned SendCloser // should be closed when done using it. func (d *Dialer) Dial() (SendCloser, error) { conn, err := netDialTimeout("tcp", addr(d.Host, d.Port), 10*time.Second) if err != nil { return nil, err } if d.SSL { conn = tlsClient(conn, d.tlsConfig()) } c, err := smtpNewClient(conn, d.Host) if err != nil { return nil, err } if d.LocalName != "" { if err := c.Hello(d.LocalName); err != nil { return nil, err } } if !d.SSL { if ok, _ := c.Extension("STARTTLS"); ok { if err := c.StartTLS(d.tlsConfig()); err != nil { c.Close() return nil, err } } } if d.Auth == nil && d.Username != "" { if ok, auths := c.Extension("AUTH"); ok { if strings.Contains(auths, "CRAM-MD5") { d.Auth = smtp.CRAMMD5Auth(d.Username, d.Password) } else if strings.Contains(auths, "LOGIN") && !strings.Contains(auths, "PLAIN") { d.Auth = &loginAuth{ username: d.Username, password: d.Password, host: d.Host, } } else { d.Auth = smtp.PlainAuth("", d.Username, d.Password, d.Host) } } } if d.Auth != nil { if err = c.Auth(d.Auth); err != nil { c.Close() return nil, err } } return &smtpSender{c, d}, nil } func (d *Dialer) tlsConfig() *tls.Config { if d.TLSConfig == nil { return &tls.Config{ServerName: d.Host} } return d.TLSConfig } func addr(host string, port int) string { return fmt.Sprintf("%s:%d", host, port) } // DialAndSend opens a connection to the SMTP server, sends the given emails and // closes the connection. func (d *Dialer) DialAndSend(m ...*Message) error { s, err := d.Dial() if err != nil { return err } defer s.Close() return Send(s, m...) } type smtpSender struct { smtpClient d *Dialer } func (c *smtpSender) Send(from string, to []string, msg io.WriterTo) error { if err := c.Mail(from); err != nil { if err == io.EOF { // This is probably due to a timeout, so reconnect and try again. sc, derr := c.d.Dial() if derr == nil { if s, ok := sc.(*smtpSender); ok { *c = *s return c.Send(from, to, msg) } } } return err } for _, addr := range to { if err := c.Rcpt(addr); err != nil { return err } } w, err := c.Data() if err != nil { return err } if _, err = msg.WriteTo(w); err != nil { w.Close() return err } return w.Close() } func (c *smtpSender) Close() error { return c.Quit() } // Stubbed out for tests. var ( netDialTimeout = net.DialTimeout tlsClient = tls.Client smtpNewClient = func(conn net.Conn, host string) (smtpClient, error) { return smtp.NewClient(conn, host) } ) type smtpClient interface { Hello(string) error Extension(string) (bool, string) StartTLS(*tls.Config) error Auth(smtp.Auth) error Mail(string) error Rcpt(string) error Data() (io.WriteCloser, error) Quit() error Close() error }
DialAndSend ,首先调用Dial方法创建连接，然后发送邮件，最后关闭链接，如果要频繁发邮件，那么是否保持长连接更好了？这里的Dial 调用了smtp.NewClient 创建smtp.Client对象c,然后调用c.Hello ,c.Auth，send 实际是调用c.Mail,c.Rcpt,c.Data，那么我们可以自己调用Dial方法 然后循环调用send方法，最后在close。
代码如下：
func SendMailByGomailTwo() { d := gomail.NewDialer("smtp.163.com", 25, "dz45693@163.com", "xxx") m := gomail.NewMessage() m.SetAddressHeader("From", "dz45693@163.com", "dz45693") m.SetHeader("To", "dz45693@sina.com") m.SetHeader("Subject", "hello SendMailByGomailtwo!") m.Embed("d:\\Downloads\\1.png") m.SetBody("text/html", "此处为正文121333!SendMailByGomailtwo") s, err := d.Dial() if err != nil { panic(err) } defer s.Close() err = gomail.Send(s, m) if err != nil { panic(err) } m.Reset() m.SetAddressHeader("From", "dz45693@163.com", "dz45693") m.SetHeader("To", "dz45693@sina.com") m.SetHeader("Subject", "hello SendMailByGomailthree!") m.Embed("d:\\Downloads\\2.png") m.SetBody("text/html", "此处为正文1SendMailByGomailthreeSendMailByGomailthree!") err = gomail.Send(s, m) if err != nil { panic(err) } }
运行结果：
windows技术爱好者
