|
@@ -0,0 +1,49 @@
|
|
|
|
|
+# 15.3 访问并读取页面
|
|
|
|
|
+
|
|
|
|
|
+在下边这个程序中，数组中的url都将被访问：会发送一个简单的`http.Head()`请求查看返回值；它的声明如下：`func Head(url string) (r *Response, err error)`
|
|
|
|
|
+
|
|
|
|
|
+返回状态码会被打印出来。
|
|
|
|
|
+
|
|
|
|
|
+示例 15.7 [poll_url.go](examples/chapter_15/poll_url.go)：
|
|
|
|
|
+```go
|
|
|
|
|
+package main
|
|
|
|
|
+
|
|
|
|
|
+import (
|
|
|
|
|
+ "fmt"
|
|
|
|
|
+ "net/http"
|
|
|
|
|
+)
|
|
|
|
|
+
|
|
|
|
|
+var urls = []string{
|
|
|
|
|
+ "http://www.google.com/",
|
|
|
|
|
+ "http://golang.org/",
|
|
|
|
|
+ "http://blog.golang.org/",
|
|
|
|
|
+}
|
|
|
|
|
+
|
|
|
|
|
+func main() {
|
|
|
|
|
+ // Execute an HTTP HEAD request for all url's
|
|
|
|
|
+ // and returns the HTTP status string or an error string.
|
|
|
|
|
+ for _, url := range urls {
|
|
|
|
|
+ resp, err := http.Head(url)
|
|
|
|
|
+ if err != nil {
|
|
|
|
|
+ fmt.Println("Error:", url, err)
|
|
|
|
|
+ }
|
|
|
|
|
+ fmt.Print(url, ": ", resp.Status)
|
|
|
|
|
+ }
|
|
|
|
|
+}
|
|
|
|
|
+```
|
|
|
|
|
+输出为：
|
|
|
|
|
+```
|
|
|
|
|
+http://www.google.com/ : 302 Found
|
|
|
|
|
+http://golang.org/ : 200 OK
|
|
|
|
|
+http://blog.golang.org/ : 200 OK
|
|
|
|
|
+```
|
|
|
|
|
+***译者注*** 由于国内的网络环境现状，很有可能见到如下超时错误提示：
|
|
|
|
|
+```
|
|
|
|
|
+Error: http://www.google.com/ Head http://www.google.com/: dial tcp 216.58.221.100:80: connectex: A connection attempt failed because the connected pa
|
|
|
|
|
+rty did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
|
|
|
|
|
+```
|
|
|
|
|
+在下边的程序中我们使用`http.Get()`获取网页内容； `Get`的返回值`res`中的`Body`属性包含了网页内容，然后我们用`ioutil.ReadAll`把它读出来：
|
|
|
|
|
+
|
|
|
|
|
+示例 15.8 [http_fetch.go](examples/chapter_15/http_fetch.go)：
|
|
|
|
|
+```go
|
|
|
|
|
+```
|
glight2000