Golang的http包功能非常完善，提供了HTTP客户端和服务端的实现。支持Get、Head、Post和PostForm函数发出HTTP/ HTTPS请求，HTTP Head的设置。
简单的http客户端demo，即客户端请求服务端
package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
)
func main() {
resp, err := http.Get("http://www.baidu.com")
if err != nil {
fmt.Fprint(os.Stdout,err)
}
defer resp.Body.Close()
bytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
fmt.Fprint(os.Stdout,err)
}
fmt.Println("返回打印结果：", string(bytes))
}上面的代码是将百度作为服务端，由本地发起请求，将百度返回内容打印输出。
简单的http服务端demo
package main
import (
"io"
"log"
"net/http"
)
func httpHandleFun(w http.ResponseWriter, r *http.Request) {
io.WriteString(w,"Hello Web")
}
func main() {
http.HandleFunc("/hello", httpHandleFun)
serve := http.ListenAndServe("localhost:8080", nil)
if serve != nil {
log.Fatal(serve)
}
}代码种http.HandleFunc()，该方法用于分发请求，即针对某一路径请求将其映射到指定的业务逻辑处理方法中。
上例中，我们在浏览器地址栏输入：http://localhost:8080/hello
浏览器页面输出：Hello Web
我们第一个http程序就成功了。
我们现在使用一个完整的示例，来练习Golang的http编程。
这个demo的功能包括：
1、图片上传
2、上传后跳转到图片查看页面
3、图片上传列表页面
package main
import (
"io"
"io/ioutil"
"log"
"net/http"
"os"
)
/**
图片上传
*/
func uploadHandler(w http.ResponseWriter, r *http.Request) {
if r.Method == "GET" {
io.WriteString(w, "<html><body><form method=\"POST\" action=\"http://localhost:8080/upload\" "+
" enctype=\"multipart/form-data\">"+
"Choose an image to upload: <input name=\"image\" type=\"file\" />"+
"<input type=\"submit\" value=\"Upload\" />"+
"</form></body></html>")
return
}
if r.Method == "POST" {
log.Println("post")
file, header, e := r.FormFile("image")
if e != nil {
log.Fatal(e)
return
}
s := header.Filename
create, e := os.Create("d:/images/" + s)
defer create.Close()
if e != nil {
log.Fatal(e)
return
}
_, e = io.Copy(create, file)
if e != nil {
log.Fatal(e)
return
}
http.Redirect(w,r,"/view?id="+s,http.StatusFound)
}
}
/**
图片显示
*/
func viewHandler(w http.ResponseWriter, r *http.Request) {
value := r.FormValue("id")
imagePath := "d://images/" + value
if isExist(imagePath) {
w.Header().Set("Content-Type","image")
http.ServeFile(w,r, imagePath)
} else {
http.NotFound(w,r)
}
}
func isExist(name string) bool {
_, e := os.Stat(name)
if e != nil {
return false
} else {
return true
}
}
func listHandle(w http.ResponseWriter, r *http.Request) {
infos, e := ioutil.ReadDir("d:/images/")
if e != nil {
log.Fatal("查看列表出错：",e)
}
var listHtml string
for _,fi := range infos {
listHtml += "<li><a href=\"/view?id="+ fi.Name() +"\"> "+ fi.Name() +" </a></li>"
}
listHtml = "<html><body><ol>"+ listHtml +"</ol></body></html>"
io.WriteString(w,listHtml)
return
}
func main() {
log.Println("main start")
http.HandleFunc("/view", viewHandler)
http.HandleFunc("/upload", uploadHandler)
http.HandleFunc("/list", listHandle)
err := http.ListenAndServe(":8080", nil)
if err != nil {
log.Fatal("ListenAndServe: ", err.Error())
}
log.Println("main end")
}