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Go语言学习之10Web开发与Mysql数据库

原作者: [db:作者] 来自: [db:来源] 收藏 邀请

本节主要内容:

1. http编程
2. mysql使用

1. http编程

(1)http编程分析

  • Go原生支持http,import(“net/http”)
  • Go的http服务性能和nginx比较接近
  • 几行代码就可以实现一个web服务

      关于HTTP,TCP/IP相关知识可以看系列博客 https://www.jianshu.com/p/dfbac2ff2657

      首先来看一个最简单的http服务器:

 1 package main
 2 
 3 import (
 4     "io"
 5     "log"
 6     "net/http"
 7 )
 8 
 9 func main() {
10     // Hello world, the web server
11 
12     helloHandler := func(w http.ResponseWriter, req *http.Request) {
13         io.WriteString(w, "Hello, world!\n")
14     }
15 
16     http.HandleFunc("/hello", helloHandler)
17     log.Fatal(http.ListenAndServe(":8080", nil))
18 }
http server(hello world)

      执行结果:

      几个函数及接口定义:

  • HandleFunc
func HandleFunc(pattern string, handler func(ResponseWriter, *Request))

HandleFunc registers the handler function for the given pattern in the DefaultServeMux. The documentation for ServeMux explains how patterns 
are matched.
 1 package main
 2 
 3 import (
 4     "io"
 5     "log"
 6     "net/http"
 7 )
 8 
 9 func main() {
10     h1 := func(w http.ResponseWriter, _ *http.Request) {
11         io.WriteString(w, "Hello from a HandleFunc #1!\n")
12     }
13     h2 := func(w http.ResponseWriter, _ *http.Request) {
14         io.WriteString(w, "Hello from a HandleFunc #2!\n")
15     }
16 
17     http.HandleFunc("/", h1)
18     http.HandleFunc("/endpoint", h2)
19 
20     log.Fatal(http.ListenAndServe(":8080", nil))
21 }
HandleFunc
  • ResponseWriter接口
A ResponseWriter interface is used by an HTTP handler to construct an HTTP response.
A ResponseWriter may not be used after the Handler.ServeHTTP method has returned.
 1 type ResponseWriter interface {
 2         // Header returns the header map that will be sent by
 3         // WriteHeader. The Header map also is the mechanism with which
 4         // Handlers can set HTTP trailers.
 5         //
 6         // Changing the header map after a call to WriteHeader (or
 7         // Write) has no effect unless the modified headers are
 8         // trailers.
 9         //
10         // There are two ways to set Trailers. The preferred way is to
11         // predeclare in the headers which trailers you will later
12         // send by setting the "Trailer" header to the names of the
13         // trailer keys which will come later. In this case, those
14         // keys of the Header map are treated as if they were
15         // trailers. See the example. The second way, for trailer
16         // keys not known to the Handler until after the first Write,
17         // is to prefix the Header map keys with the TrailerPrefix
18         // constant value. See TrailerPrefix.
19         //
20         // To suppress automatic response headers (such as "Date"), set
21         // their value to nil.
22         Header() Header
23 
24         // Write writes the data to the connection as part of an HTTP reply.
25         //
26         // If WriteHeader has not yet been called, Write calls
27         // WriteHeader(http.StatusOK) before writing the data. If the Header
28         // does not contain a Content-Type line, Write adds a Content-Type set
29         // to the result of passing the initial 512 bytes of written data to
30         // DetectContentType. Additionally, if the total size of all written
31         // data is under a few KB and there are no Flush calls, the
32         // Content-Length header is added automatically.
33         //
34         // Depending on the HTTP protocol version and the client, calling
35         // Write or WriteHeader may prevent future reads on the
36         // Request.Body. For HTTP/1.x requests, handlers should read any
37         // needed request body data before writing the response. Once the
38         // headers have been flushed (due to either an explicit Flusher.Flush
39         // call or writing enough data to trigger a flush), the request body
40         // may be unavailable. For HTTP/2 requests, the Go HTTP server permits
41         // handlers to continue to read the request body while concurrently
42         // writing the response. However, such behavior may not be supported
43         // by all HTTP/2 clients. Handlers should read before writing if
44         // possible to maximize compatibility.
45         Write([]byte) (int, error)
46 
47         // WriteHeader sends an HTTP response header with the provided
48         // status code.
49         //
50         // If WriteHeader is not called explicitly, the first call to Write
51         // will trigger an implicit WriteHeader(http.StatusOK).
52         // Thus explicit calls to WriteHeader are mainly used to
53         // send error codes.
54         //
55         // The provided code must be a valid HTTP 1xx-5xx status code.
56         // Only one header may be written. Go does not currently
57         // support sending user-defined 1xx informational headers,
58         // with the exception of 100-continue response header that the
59         // Server sends automatically when the Request.Body is read.
60         WriteHeader(statusCode int)
61 }
type ResponseWriter interface
  •  ListenAndServe
func ListenAndServe(addr string, handler Handler) error
ListenAndServe listens on the TCP network address addr and then calls Serve with handler to handle requests on incoming connections. 
Accepted connections are configured to enable TCP keep
-alives. The handler is typically nil, in which case the DefaultServeMux is used. ListenAndServe always returns a non-nil error.

      具体实现过程需要分析:后续补上。

(2)http常见请求方法
    1)Get请求
    2)Post请求
    3)Put请求
    4)Delete请求
    5)Head请求

 1 package main
 2 
 3 import (
 4     "fmt"
 5     "io/ioutil"
 6     "net/http"
 7 )
 8 
 9 func main() {
10     res, err := http.Get("https://www.baidu.com/")
11     if err != nil {
12         fmt.Println("get err:", err)
13         return
14     }
15 
16     data, err := ioutil.ReadAll(res.Body)
17     if err != nil {
18         fmt.Println("get data err:", err)
19         return
20     }
21 
22     fmt.Println(string(data))
23 }
Get请求示例
 1 package main
 2 
 3 import (
 4     "fmt"
 5     "net/http"
 6 )
 7 
 8 var url = []string{
 9     "http://www.baidu.com",
10     "http://google.com",
11     "http://taobao.com",
12 }
13 
14 func main() {
15 
16     for _, v := range url {
17         resp, err := http.Head(v)
18         if err != nil {
19             fmt.Printf("head %s failed, err:%v\n", v, err)
20             continue
21         }
22 
23         fmt.Printf("head succ, status:%v\n", resp.Status)
24     }
25 }
Head请求示例
  • Get
 1 func (c *Client) Get(url string) (resp *Response, err error)
 2   
 3 Get issues a GET to the specified URL. If the response is one of the following redirect codes, Get follows the redirect after calling the Client's CheckRedirect function:
 4 
 5 301 (Moved Permanently)
 6 302 (Found)
 7 303 (See Other)
 8 307 (Temporary Redirect)
 9 308 (Permanent Redirect)
10 An error is returned if the Client's CheckRedirect function fails or if there was an HTTP protocol error. A non-2xx response doesn't cause an error. Any returned error will be of type *url.Error. The url.Error value's Timeout method will report true if request timed out or was canceled.
11 
12 When err is nil, resp always contains a non-nil resp.Body. Caller should close resp.Body when done reading from it.
13 
14 To make a request with custom headers, use NewRequest and Client.Do.
Get
  • Head
 1 func Head(url string) (resp *Response, err error)
 2 
 3 func (c *Client) Head(url string) (resp *Response, err error)
 4 Head issues a HEAD to the specified URL. If the response is one of the following redirect codes, Head follows the redirect after calling the Client's CheckRedirect function:
 5 
 6 301 (Moved Permanently)
 7 302 (Found)
 8 303 (See Other)
 9 307 (Temporary Redirect)
10 308 (Permanent Redirect)
Head
  • Response
 1 type Response struct {
 2         Status     string // e.g. "200 OK"
 3         StatusCode int    // e.g. 200
 4         Proto      string // e.g. "HTTP/1.0"
 5         ProtoMajor int    // e.g. 1
 6         ProtoMinor int    // e.g. 0
 7 
 8         // Header maps header keys to values. If the response had multiple
 9         // headers with the same key, they may be concatenated, with comma
10         // delimiters.  (RFC 7230, section 3.2.2 requires that multiple headers
11         // be semantically equivalent to a comma-delimited sequence.) When
12         // Header values are duplicated by other fields in this struct (e.g.,
13         // ContentLength, TransferEncoding, Trailer), the field values are
14         // authoritative.
15         //
16         // Keys in the map are canonicalized (see CanonicalHeaderKey).
17         Header Header
18 
19         // Body represents the response body.
20         //
21         // The response body is streamed on demand as the Body field
22         // is read. If the network connection fails or the server
23         // terminates the response, Body.Read calls return an error.
24         //
25         // The http Client and Transport guarantee that Body is always
26         // non-nil, even on responses without a body or responses with
27         // a zero-length body. It is the caller's responsibility to
28         // close Body. The default HTTP client's Transport may not
29         // reuse HTTP/1.x "keep-alive" TCP connections if the Body is
30         // not read to completion and closed.
31         //
32         // The Body is automatically dechunked if the server replied
33         // with a "chunked" Transfer-Encoding.
34         //
35         // As of Go 1.12, the Body will be also implement io.Writer
36         // on a successful "101 Switching Protocols" responses,
37         // as used by WebSockets and HTTP/2's "h2c" mode.
38         Body io.ReadCloser
39 
40         // ContentLength records the length of the associated content. The
41         // value -1 indicates that the length is unknown. Unless Request.Method
42         // is "HEAD", values >= 0 indicate that the given number of bytes may
43         // be read from Body.
44         ContentLength int64
45 
46         // Contains transfer encodings from outer-most to inner-most. Value is
47         // nil, means that "identity" encoding is used.
48         TransferEncoding []string
49 
50         // Close records whether the header directed that the connection be
51         // closed after reading Body. The value is advice for clients: neither
52         // ReadResponse nor Response.Write ever closes a connection.
53         Close bool
54 
55         // Uncompressed reports whether the response was sent compressed but
56         // was decompressed by the http package. When true, reading from
57         // Body yields the uncompressed content instead of the compressed
58         // content actually set from the server, ContentLength is set to -1,
59         // and the "Content-Length" and "Content-Encoding" fields are deleted
60         // from the responseHeader. To get the original response from
61         // the server, set Transport.DisableCompression to true.
62         Uncompressed bool // Go 1.7
63 
64         // Trailer maps trailer keys to values in the same
65         // format as Header.
66         //
67         // The Trailer initially contains only nil values, one for
68         // each key specified in the server's "Trailer" header
69         // value. Those values are not added to Header.
70         //
71         // Trailer must not be accessed concurrently with Read calls
72         // on the Body.
73         //
74         // After Body.Read has returned io.EOF, Trailer will contain
75         // any trailer values sent by the server.
76         Trailer Header
77 
78         // Request is the request that was sent to obtain this Response.
79         // Request's Body is nil (having already been consumed).
80         // This is only populated for Client requests.
81         Request *Request
82 
83         // TLS contains information about the TLS connection on which the
84         // response was received. It is nil for unencrypted responses.
85         // The pointer is shared between responses and should not be
86         // modified.
87         TLS *tls.ConnectionState // Go 1.3
88 }
Response
  •  http 常见状态码
http.StatusContinue = 100
http.StatusOK = 200
http.StatusFound = 302
http.StatusBadRequest = 400
http.StatusUnauthorized = 401
http.StatusForbidden = 403
http.StatusNotFound = 404
http.StatusInternalServerError = 500

(3)表单处理

 1 package main
 2 import (
 3     "io"
 4     "net/http"
 5 )
 6 
 7 const form = `<html><body><form action="#" method="post" name="bar">
 8                     <input type="text" name="in"/>
 9                     <input type="text" name="in"/>
10                      <input type="submit" value="Submit"/>
11              </form></html></body>`
12 
13 func SimpleServer(w http.ResponseWriter, request *http.Request) {
14     io.WriteString(w, "<h1>hello, world</h1>")
15 }
16 
17 func FormServer(w http.ResponseWriter, request *http.Request) {
18     w.Header().Set("Content-Type", "text/html")
19     switch request.Method {
20     case "GET":
21         io.WriteString(w, form)
22     case "POST":
23         request.ParseForm()
24         io.WriteString(w, request.Form["in"][0])
25         io.WriteString(w, "\n")
26         io.WriteString(w, request.FormValue("in"))
27     }
28 }
29 func main() {
30     http.HandleFunc("/test1", SimpleServer)
31     http.HandleFunc("/test2", FormServer)
32     if err := http.ListenAndServe(":8088", nil); err != nil {
33     }
34 }
form表单处理

    执行结果:

    url: test1

 

    url: test2(第一次请求是GET,第二次是POST请求)

    GET请求:

 

    POST请求:

(4)模板

    1)替换 {{.字段名}}

     模板中的点(.)为结构体中的p

 1 package main
 2 
 3 import (
 4     "fmt"
 5     "os"
 6     "text/template"
 7 )
 8 
 9 type Person struct {
10     Name string
11     Age  string
12     Title string
13 }
14 
15 func main() {
16     t, err := template.ParseFiles("./index.html")
17     if err != nil {
18         fmt.Println("parse file err:", err)
19         return
20     }
21     p := Person{Name: "Mary", Age: "31", Title:"My blog"}
22     if err := t.Execute(os.Stdout, p); err != nil {
23         fmt.Println("There was an error:", err.Error())
24     }
25 }
template.go
1 <html>
2     <head>
3         <title>{{.Title}}</title>
4     </head>
5     <body>
6         <p> hello, {{.Name}}</p>
7         <p> {{.}}</p>
8     </body>
9 </html>
index.html

    2)if判断

 1 package main
 2 
 3 import (
 4     "fmt"
 5     "os"
 6     "text/template"
 7 )
 8 
 9 type Person struct {
10     Name string
11     Age  int
12     Title string
13 }
14 
15 func main() {
16     t, err := template.ParseFiles("./index2.html")
17     if err != nil {
18         fmt.Println("parse file err:", err)
19         return
20     }
21     p := Person{Name: "Mary", Age: 17, Title:"My blog"}
22     if err := t.Execute(os.Stdout, p); err != nil {
23         fmt.Println( 
                       
                    
                    

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