使用 Cloud Storage

您可以使用 Cloud Storage 来存储和提供文件，例如电影、图片或其他静态内容。

本文档介绍了如何在应用中使用 Google Cloud 客户端库将数据存储在 Cloud Storage 中，以及如何从 Cloud Storage 检索数据。

准备工作

  • 请按照 App Engine Go 版“Hello, World!”中的说明设置您的环境和项目，并了解如何在 App Engine 中构建 Go 应用。记下并保存项目 ID，因为您需要用它来运行本文档中所述的示例应用。

  • 请务必调用以下命令，为您的应用创建 Cloud Storage 存储分区：

    gsutil mb gs://[YOUR_BUCKET_NAME]

  • 将此存储分区设为可公开读取，以便其可以传送文件：

    gsutil defacl set public-read gs://[YOUR_BUCKET_NAME]

下载示例

如需克隆代码库，请执行以下命令：

go get -d -v github.com/GoogleCloudPlatform/golang-samples/storage
cd $GOPATH/src/github.com/GoogleCloudPlatform/golang-samples/appengine_flexible/storage

修改项目配置并安装依赖项

在 app.yaml 中设置 GCLOUD_STORAGE_BUCKET。此值是您之前创建的 Cloud Storage 存储分区的名称。

appengine_flexible/storage/app.yaml 
# Copyright 2019 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

runtime: go
env: flex

automatic_scaling:
  min_num_instances: 1

env_variables:
  GCLOUD_STORAGE_BUCKET: your-bucket-name

应用代码

示例应用会显示一个网页，提示用户选择要存储在 Cloud Storage 中的文件。在用户选择文件并点击“提交”后，上传处理程序会通过 Cloud Storage NewWriter 功能将文件写入 Cloud Storage 存储分区。

请注意，要从 Cloud Storage 中检索此文件，您需要指定存储分区名称和文件名。您应将这些值存储在应用中以备将来使用。

appengine_flexible/storage/storage.go 
// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Sample storage demonstrates use of the cloud.google.com/go/storage package from App Engine flexible environment.
package main

import (
	"context"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"

	"cloud.google.com/go/storage"
	"google.golang.org/appengine"
)

var (
	storageClient *storage.Client

	// Set this in app.yaml when running in production.
	bucket = os.Getenv("GCLOUD_STORAGE_BUCKET")
)

func main() {
	ctx := context.Background()

	var err error
	storageClient, err = storage.NewClient(ctx)
	if err != nil {
		log.Fatal(err)
	}

	http.HandleFunc("/", formHandler)
	http.HandleFunc("/upload", uploadHandler)

	appengine.Main()
}

func uploadHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, "", http.StatusMethodNotAllowed)
		return
	}

	ctx := appengine.NewContext(r)

	f, fh, err := r.FormFile("file")
	if err != nil {
		msg := fmt.Sprintf("Could not get file: %v", err)
		http.Error(w, msg, http.StatusBadRequest)
		return
	}
	defer f.Close()

	sw := storageClient.Bucket(bucket).Object(fh.Filename).NewWriter(ctx)
	if _, err := io.Copy(sw, f); err != nil {
		msg := fmt.Sprintf("Could not write file: %v", err)
		http.Error(w, msg, http.StatusInternalServerError)
		return
	}

	if err := sw.Close(); err != nil {
		msg := fmt.Sprintf("Could not put file: %v", err)
		http.Error(w, msg, http.StatusInternalServerError)
		return
	}

	u, _ := url.Parse("/" + bucket + "/" + sw.Attrs().Name)

	fmt.Fprintf(w, "Successful! URL: https://storage.googleapis.com%s", u.EscapedPath())
}

func formHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprint(w, formHTML)
}

const formHTML = `<!DOCTYPE html>
<html>
  <head>
    <title>Storage</title>
    <meta charset="utf-8">
  </head>
  <body>
    <form method="POST" action="/upload" enctype="multipart/form-data">
      <input type="file" name="file">
      <input type="submit">
    </form>
  </body>
</html>`

了解详情

如需全面了解 Cloud Storage，请参阅 Cloud Storage 文档。