Create 15.3.md

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+# 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
+```