download attachment worked. (with eye witnessed test)

crmAttachment.go

 	return
 }
 
-func crmDownloadAttachment(fileID, saveAs string) (err error) {
+func crmDownloadAttachmentAs(fileID, saveAs string) (err error) {
 	return nil
 }
+
+func crmDownloadAttachment(fileID string) (err error) {
+	u := crmURL4DownloadAttachmet(fileID)
+	headers := map[string]string{}
+	headers["Authorization"] = crmAuthHeader()
+	f, _, err := saveURLwithHTTPHeader(u, headers)
+	log.Println(f)
+	return nil
+}
+
+func crmURL4DownloadAttachmet(fileID string) string {
+	return CRMConfig.BaseURL + "?entryPoint=download&id=" + fileID
+}

crmAttachment_test.go

 	err := json.Unmarshal([]byte(msg), &info)
 	AssertEqual(t, err, nil, "json decode shold be correct")
 }
+
+func TestCRMDownloadAttachment(t *testing.T) {
+	SetupConfig()
+	crmDownloadAttachment("591ef9c61d6ca779c")
+}

download.go

 )
 
 func saveURL(url string) (tmpFile string, contentType string, err error) {
-	log.Println("saveURL: " + url)
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return
+	}
+	return saveHTTPRequest(req)
+}
+
+//{"video_url":"http://153.37.232.145/vweixinp.tc.qq.com/1007_6475d21fb443453b8adeac7e59cc0e1c.f10.mp4?vkey=E79C6B0DA06E7A434D15E24774F91412386D1956768C400AC93ECA5320ACAAAF050E1E1BA5C22DFD81B5EE3FBA97E928E0FC2DC597CF611B3E6641BC1AEE2892736FFE29E993F200AA4A0811FEB4E234C48516131207DDE4&sha=0&save=1"}
+type videoURL struct {
+	VideoURL string `json:"video_url"`
+}
+
+//readVideoURL try to read a file into json structure
+//containing video_url
+//
+func readVideoURL(path string) (u string) {
+	body, err := ioutil.ReadFile(path)
+	if err == nil {
+		var v = videoURL{}
+		err = json.Unmarshal([]byte(body), &v)
+		if err == nil {
+			_, err = url.ParseRequestURI(v.VideoURL)
+			if err == nil {
+				return v.VideoURL
+			}
+		}
+	}
+	return ""
+}
+
+func buildHTTPReqWithHeader(httpMethod, targetURL string, headers map[string]string) (req *http.Request, err error) {
+	req, err = http.NewRequest(httpMethod, targetURL, nil)
+	if err != nil {
+		return
+	}
+
+	if headers != nil {
+		for k, v := range headers {
+			req.Header.Set(k, v)
+		}
+	}
+	return
+}
+
+func saveHTTPRequest(req *http.Request) (tmpFile string, contentType string, err error) {
 	var myClient = &http.Client{Timeout: 20 * time.Second}
-	r, err := myClient.Get(url)
+
+	r, err := myClient.Do(req)
 	if err != nil {
-		log.Fatal("Fail to get URL:" + url)
-		log.Fatal(err)
+		log.Printf("Fail to get URL: %s", req.RequestURI)
+		log.Println(err)
 		return "", "", err
 	}
 	defer r.Body.Close()
 	return
 }
 
-//{"video_url":"http://153.37.232.145/vweixinp.tc.qq.com/1007_6475d21fb443453b8adeac7e59cc0e1c.f10.mp4?vkey=E79C6B0DA06E7A434D15E24774F91412386D1956768C400AC93ECA5320ACAAAF050E1E1BA5C22DFD81B5EE3FBA97E928E0FC2DC597CF611B3E6641BC1AEE2892736FFE29E993F200AA4A0811FEB4E234C48516131207DDE4&sha=0&save=1"}
-type videoURL struct {
-	VideoURL string `json:"video_url"`
-}
-
-//readVideoURL try to read a file into json structure
-//containing video_url
-//
-func readVideoURL(path string) (u string) {
-	body, err := ioutil.ReadFile(path)
-	if err == nil {
-		var v = videoURL{}
-		err = json.Unmarshal([]byte(body), &v)
-		if err == nil {
-			_, err = url.ParseRequestURI(v.VideoURL)
-			if err == nil {
-				return v.VideoURL
-			}
-		}
+func saveURLwithHTTPHeader(url string, headers map[string]string) (tmpFile string, contentType string, err error) {
+	log.Println("saveURL: " + url)
+	req, err := buildHTTPReqWithHeader("GET", url, headers)
+	if err != nil {
+		return
 	}
-	return ""
+	return saveHTTPRequest(req)
 }