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快速入门:使用计算机视觉 REST API 和 Go 分析远程图像Quickstart: Analyze a remote image using the Computer Vision REST API with Go

在本快速入门中,你将使用计算机视觉的 REST API 分析远程存储的图像以提取视觉特征。In this quickstart, you analyze a remotely stored image to extract visual features by using Computer Vision's REST API. 使用分析图像方法,可以根据图像内容提取视觉特征。With the Analyze Image method, you can extract visual features based on image content.

如果没有 Azure 订阅,请在开始之前创建一个免费帐户If you don't have an Azure subscription, create a free account before you begin.

先决条件Prerequisites

创建并运行示例Create and run the sample

要创建和运行示例,请执行以下步骤:To create and run the sample, do the following steps:

  1. 将以下代码复制到文本编辑器中。Copy the below code into a text editor.
  2. 必要时在代码中进行如下更改:Make the following changes in code where needed:
    1. subscriptionKey 的值替换为你的订阅密钥。Replace the value of subscriptionKey with your subscription key.
    2. 如有必要,请将 uriBase 的值替换为获取的订阅密钥所在的 Azure 区域中的分析图像方法的终结点 URL。Replace the value of uriBase with the endpoint URL for the Analyze Image method from the Azure region where you obtained your subscription keys, if necessary.
    3. (可选)将 imageUrl 的值替换为要分析的其他图像的 URL。Optionally, replace the value of imageUrl with the URL of a different image that you want to analyze.
  3. 将代码保存为以 .go 为扩展名的文件。Save the code as a file with a .go extension. 例如,analyze-image.goFor example, analyze-image.go.
  4. 打开命令提示符窗口。Open a command prompt window.
  5. 在提示符处运行 go build 命令,对文件中的包进行编译。At the prompt, run the go build command to compile the package from the file. 例如,go build analyze-image.goFor example, go build analyze-image.go.
  6. 在提示符处,运行所编译的包。At the prompt, run the compiled package. 例如,analyze-imageFor example, analyze-image.
package main

import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "net/http"
    "strings"
    "time"
)

func main() {
    // Replace <Subscription Key> with your valid subscription key.
    const subscriptionKey = "<Subscription Key>"

    // You must use the same Azure region in your REST API method as you used to
    // get your subscription keys. For example, if you got your subscription keys
    // from the West US region, replace "westcentralus" in the URL
    // below with "westus".
    //
    // Free trial subscription keys are generated in the "westcentralus" region.
    // If you use a free trial subscription key, you shouldn't need to change
    // this region.
    const uriBase =
        "https://westcentralus.api.cognitive.microsoft.com/vision/v2.0/analyze"
    const imageUrl =
        "https://upload.wikimedia.org/wikipedia/commons/3/3c/Shaki_waterfall.jpg"

    const params = "?visualFeatures=Description&details=Landmarks&language=en"
    const uri = uriBase + params
    const imageUrlEnc = "{\"url\":\"" + imageUrl + "\"}"

    reader := strings.NewReader(imageUrlEnc)

    // Create the HTTP client
    client := &http.Client{
        Timeout: time.Second * 2,
    }

    // Create the POST request, passing the image URL in the request body
    req, err := http.NewRequest("POST", uri, reader)
    if err != nil {
        panic(err)
    }

    // Add request headers
    req.Header.Add("Content-Type", "application/json")
    req.Header.Add("Ocp-Apim-Subscription-Key", subscriptionKey)

    // Send the request and retrieve the response
    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }

    defer resp.Body.Close()

    // Read the response body
    // Note, data is a byte array
    data, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        panic(err)
    }

    // Parse the JSON data from the byte array
    var f interface{}
    json.Unmarshal(data, &f)

    // Format and display the JSON result
    jsonFormatted, _ := json.MarshalIndent(f, "", "  ")
    fmt.Println(string(jsonFormatted))
}

检查响应Examine the response

成功的响应以 JSON 格式返回。A successful response is returned in JSON. 示例应用程序会在命令提示符窗口中分析和显示成功响应,如下例所示:The sample application parses and displays a successful response in the command prompt window, similar to the following example:

{
  "categories": [
    {
      "detail": {
        "landmarks": []
      },
      "name": "outdoor_water",
      "score": 0.9921875
    }
  ],
  "description": {
    "captions": [
      {
        "confidence": 0.916458423253597,
        "text": "a large waterfall over a rocky cliff"
      }
    ],
    "tags": [
      "nature",
      "water",
      "waterfall",
      "outdoor",
      "rock",
      "mountain",
      "rocky",
      "grass",
      "hill",
      "covered",
      "hillside",
      "standing",
      "side",
      "group",
      "walking",
      "white",
      "man",
      "large",
      "snow",
      "grazing",
      "forest",
      "slope",
      "herd",
      "river",
      "giraffe",
      "field"
    ]
  },
  "metadata": {
    "format": "Jpeg",
    "height": 959,
    "width": 1280
  },
  "requestId": "a92f89ab-51f8-4735-a58d-507da2213fc2"
}

后续步骤Next steps

了解计算机视觉 API,它用于分析图像、检测名人和地标、创建缩略图,并提取印刷体文本和手写文本。Explore the Computer Vision API used to analyze an image, detect celebrities and landmarks, create a thumbnail, and extract printed and handwritten text. 要快速体验计算机视觉 API,请尝试使用 Open API 测试控制台To rapidly experiment with the Computer Vision API, try the Open API testing console.