如何在Google App Engine中从servlet上传文件到Google Cloud Storage？
当我这样做时，Google Cloud Storage不知道我从HTML表单发送的文件类型。上传文件到云存储的正确方法是什么？应该如何编写HTML / JavaScript和servlet代码？
从Google App Engine（Java）将文件上传到Google云存储
3
- user2354982
3
有一个谷歌示例使用了谷歌云存储JavaScript客户端库。它通过JavaScript将文件上传到云存储，因此不是通过AppEngine使用的，但是您可以在文件上传到云存储后立即调用AppEngine servlet。实际上，我在互联网上找不到这个示例了...但它非常有效，如果您感兴趣，我可以在这里发布它。 - Renaud Tarnec
是的，我有兴趣 - user2354982
你有看过这篇文章读写云存储吗？它提供了一个简单的示例和链接到工作的Github servlet文件。我建议先尝试一下，并在Stack Overflow上报告和寻求特定错误和挑战的答案，而不是一般性的如何问题。 - Nicholas
1个回答
3
以下是谷歌提供的与JavaScript交互Cloud Storage的代码示例。它不仅可以上传文件，还可以下载、创建新的存储桶等。下面是我从这个示例中衍生出来的上传功能函数。
（Note: 请勿翻译HTML标签，仅提供纯文本翻译）
以下是上传文件的函数，完全受到上面例子的启发。请注意，它使用JavaScript客户端库与Google API（gapi）交互，这意味着您可以通过Google帐户进行身份验证来保护上传(https://developers.google.com/api-client-library/javascript/start/start-js)。
（Note: 请勿翻译HTML标签，仅提供纯文本翻译）
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset='utf-8' />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script src="https://apis.google.com/js/client.js"></script>
<script type="text/javascript">
/**
* The Project ID of your Google Cloud Storage Project.
*/
var PROJECT = 'abcd';
/**
* Enter a client ID for a web application from the Google Developers
* Console on the "APIs & auth", "Credentials" page.
* In your Developers Console project add a JavaScript origin
* that corresponds to the domain from where you will be running the
* script. For more info see:
* https://developers.google.com/console/help/new/#generatingoauth2
*/
var clientId = '701111116470-55bj2lkjlkkjkljhe97di22gus5hs3.apps.googleusercontent.com';
/**
* Enter the API key from the Google Developers Console, by following these
* steps:
* 1) Visit https://cloud.google.com/console and select your project
* 2) Click on "APIs & auth" in the left column and then click “Credentials”
* 3) Find section "Public API Access" and use the "API key." If sample is
* being run on localhost then delete all "Referers" and save. Setting
* should display "Any referer allowed." For more info see:
* https://developers.google.com/console/help/new/#generatingdevkeys
*/
var apiKey = 'JHJhhguy8786875hghgjbS0nYjcMY';
/**
* To enter one or more authentication scopes, refer to the documentation
* for the API.
*/
var scopes = 'https://www.googleapis.com/auth/devstorage.full_control';
/**
* Constants for request parameters. Fill these values in with your custom
* information.
*/
var API_VERSION = 'v1';
/**
* Enter a unique bucket name to create a new bucket. The guidelines for
* bucket naming can be found here:
* https://developers.google.com/storage/docs/bucketnaming
*/
//var BUCKET = 'code-sample-bucket-' + Date.now();
var BUCKET = 'testbucket';
/**
* The name of the object inserted via insertObject method.
*/
var object = "";
/**
* Get this value from the Developers Console. Click on the
* “Cloud Storage” service in the Left column and then select
* “Project Dashboard”. Use one of the Google Cloud Storage group IDs
* listed and combine with the prefix “group-” to get a string
* like the example below.
*/
var GROUP =
'group-kjhHJKHJKH897897878jgjghg8728f21c3ff22597efbfc63ccdb8f2294d8fd2561cb9';
/**
* Valid values are user-userId, user-email, group-groupId, group-email,
* allUsers, allAuthenticatedUsers
*/
var ENTITY = 'allUsers';
/**
* Valid values are READER, OWNER
*/
var ROLE = 'READER';
/**
* Valid values are READER, OWNER
*/
var ROLE_OBJECT = 'READER';
/**
* A list of example calls to the Google Cloud Storage JavaScript client
* library, as well as associated explanations of each call.
*/
var listApiRequestExplanations = {
'listBuckets': 'This API call queries the Google Cloud Storage API ' +
'for a list of buckets in your project, and returns the result as ' +
'a list of Google Cloud Storage buckets.',
'listObjects': 'This API call queries the Google Cloud Storage API ' +
'for a list of objects in your bucket, and returns the result as ' +
'a list of Google Cloud Storage objects.',
'listBucketsAccessControls': 'This API call queries the Google Cloud ' +
'Storage API for the list of access control lists on buckets in your ' +
'project and returns the result as a list of Google Cloud Storage ' +
'Access Control Lists.',
'listObjectsAccessControls': 'This API call queries the Google Cloud ' +
'Storage API for the list of access control lists on objects in your ' +
'bucket and returns the result as a list of Google Cloud Storage ' +
'Access Control Lists.',
'getBucket': 'This API call queries the Google Cloud Storage API ' +
'for a bucket in your project, and returns the result as a ' +
'Google Cloud Storage bucket.',
'getBucketAccessControls': 'This API call queries the Google Cloud ' +
'Storage API for the access control list on a specific bucket ' +
'and returns the result as a Google Cloud Storage Access Control List.',
'getObjectAccessControls': 'This API call queries the Google Cloud ' +
'Storage API for the access control list on a specific object ' +
'and returns the result as a Google Cloud Storage Access Control List.',
'insertBucket': 'This API call uses the Google Cloud Storage API ' +
'to insert a bucket into your project.',
'insertObject': 'This API call uses the Google Cloud Storage API ' +
'to insert an object into your bucket.',
'insertBucketAccessControls': 'This API uses the Google Cloud ' +
'Storage API to insert an access control list on a specific bucket ' +
'and returns the result as a Google Cloud Storage Access Control List.',
'insertObjectAccessControls': 'This API uses the Google Cloud ' +
'Storage API to insert an access control list on a specific object ' +
'and returns the result as a Google Cloud Storage Access Control List.',
'deleteBucket': 'This API uses the Google Cloud Storage API to delete ' +
'an empty bucket and returns an empty response to indicate success.',
'deleteObject': 'This API uses the Google Cloud Storage API to delete ' +
'an object and returns an empty response to indicate success.'
};
/**
* Google Cloud Storage API request to retrieve the list of buckets in
* your Google Cloud Storage project.
*/
function listBuckets() {
var request = gapi.client.storage.buckets.list({
'project': PROJECT
});
executeRequest(request, 'listBuckets');
}
/**
* Google Cloud Storage API request to retrieve the list of objects in
* your Google Cloud Storage project.
*/
function listObjects() {
var request = gapi.client.storage.objects.list({
'bucket': BUCKET
});
executeRequest(request, 'listObjects');
}
/**
* Google Cloud Storage API request to retrieve the access control list on
* a bucket in your Google Cloud Storage project.
*/
function listBucketsAccessControls() {
var request = gapi.client.storage.bucketAccessControls.list({
'bucket': BUCKET
});
executeRequest(request, 'listBucketsAccessControls');
}
/**
* Google Cloud Storage API request to retrieve the access control list on
* an object in your Google Cloud Storage project.
*/
function listObjectsAccessControls() {
var request = gapi.client.storage.objectAccessControls.list({
'bucket': BUCKET,
'object': object
});
executeRequest(request, 'listObjectsAccessControls');
}
/**
* Google Cloud Storage API request to retrieve a bucket in
* your Google Cloud Storage project.
*/
function getBucket() {
var request = gapi.client.storage.buckets.get({
'bucket': BUCKET
});
executeRequest(request, 'getBucket');
}
/**
* Google Cloud Storage API request to retrieve a bucket's Access Control
* List in your Google Cloud Storage project.
*/
function getBucketAccessControls() {
var request = gapi.client.storage.bucketAccessControls.get({
'bucket': BUCKET,
'entity': GROUP
});
executeRequest(request, 'getBucketAccessControls');
}
/**
* Google Cloud Storage API request to retrieve an object's Access Control
* List in your Google Cloud Storage project.
*/
function getObjectAccessControls() {
var request = gapi.client.storage.objectAccessControls.get({
'bucket': BUCKET,
'object': object,
'entity': GROUP
});
executeRequest(request, 'getObjectAccessControls');
}
/**
* Google Cloud Storage API request to insert a bucket into
* your Google Cloud Storage project.
*/
function insertBucket() {
resource = {
'name': BUCKET
};
var request = gapi.client.storage.buckets.insert({
'project': PROJECT,
'resource': resource
});
executeRequest(request, 'insertBucket');
}
/**
* Google Cloud Storage API request to insert an object into
* your Google Cloud Storage bucket.
*/
function insertObject(event) {
try{
var fileData = event.target.files[0];
}
catch(e) {
//'Insert Object' selected from the API Commands select list
//Display insert object button and then exit function
filePicker.style.display = 'block';
return;
}
const boundary = '-------314159265358979323846';
const delimiter = "\r\n--" + boundary + "\r\n";
const close_delim = "\r\n--" + boundary + "--";
var reader = new FileReader();
reader.readAsBinaryString(fileData);
reader.onload = function(e) {
var contentType = fileData.type || 'application/octet-stream';
var metadata = {
'name': fileData.name,
'mimeType': contentType
};
var base64Data = btoa(reader.result);
var multipartRequestBody =
delimiter +
'Content-Type: application/json\r\n\r\n' +
JSON.stringify(metadata) +
delimiter +
'Content-Type: ' + contentType + '\r\n' +
'Content-Transfer-Encoding: base64\r\n' +
'\r\n' +
base64Data +
close_delim;
//Note: gapi.client.storage.objects.insert() can only insert
//small objects (under 64k) so to support larger file sizes
//we're using the generic HTTP request method gapi.client.request()
var request = gapi.client.request({
'path': '/upload/storage/' + API_VERSION + '/b/' + BUCKET + '/o',
'method': 'POST',
'params': {'uploadType': 'multipart'},
'headers': {
'Content-Type': 'multipart/mixed; boundary="' + boundary + '"'
},
'body': multipartRequestBody});
//Remove the current API result entry in the main-content div
listChildren = document.getElementById('main-content').childNodes;
if (listChildren.length > 1) {
listChildren[1].parentNode.removeChild(listChildren[1]);
}
try{
//Execute the insert object request
executeRequest(request, 'insertObject');
//Store the name of the inserted object
object = fileData.name;
}
catch(e) {
alert('An error has occurred: ' + e.message);
}
}
}
/**
* Google Cloud Storage API request to insert an Access Control List into
* your Google Cloud Storage bucket.
*/
function insertBucketAccessControls() {
resource = {
'entity': ENTITY,
'role': ROLE
};
var request = gapi.client.storage.bucketAccessControls.insert({
'bucket': BUCKET,
'resource': resource
});
executeRequest(request, 'insertBucketAccessControls');
}
/**
* Google Cloud Storage API request to insert an Access Control List into
* your Google Cloud Storage object.
*/
function insertObjectAccessControls() {
resource = {
'entity': ENTITY,
'role': ROLE_OBJECT
};
var request = gapi.client.storage.objectAccessControls.insert({
'bucket': BUCKET,
'object': object,
'resource': resource
});
executeRequest(request, 'insertObjectAccessControls');
}
/**
* Google Cloud Storage API request to delete a Google Cloud Storage bucket.
*/
function deleteBucket() {
var request = gapi.client.storage.buckets.delete({
'bucket': BUCKET
});
executeRequest(request, 'deleteBucket');
}
/**
* Google Cloud Storage API request to delete a Google Cloud Storage object.
*/
function deleteObject() {
var request = gapi.client.storage.objects.delete({
'bucket': BUCKET,
'object': object
});
executeRequest(request, 'deleteObject');
}
/**
* Removes the current API result entry in the main-content div, adds the
* results of the entry for your function.
* @param {string} apiRequestName The name of the example API request.
*/
function updateApiResultEntry(apiRequestName) {
listChildren = document.getElementById('main-content')
.childNodes;
if (listChildren.length > 1) {
listChildren[1].parentNode.removeChild(listChildren[1]);
}
if (apiRequestName != 'null') {
window[apiRequestName].apply(this);
}
}
/**
* Determines which API request has been selected, and makes a call to add
* its result entry.
*/
function runSelectedApiRequest() {
var curElement = document.getElementById('api-selection-options');
var apiRequestName = curElement.options[curElement.selectedIndex].value;
updateApiResultEntry(apiRequestName);
}
/**
* Binds event listeners to handle a newly selected API request.
*/
function addSelectionSwitchingListeners() {
document.getElementById('api-selection-options')
.addEventListener('change',
runSelectedApiRequest, false);
}
/**
* Template for getting JavaScript sample code snippets.
* @param {string} method The name of the Google Cloud Storage request
* @param {string} params The parameters passed to method
*/
function getCodeSnippet(method, params) {
var objConstruction = "// Declare your parameter object\n";
objConstruction += "var params = {};";
objConstruction += "\n\n";
var param = "// Initialize your parameters \n";
for (i in params) {
param += "params['" + i + "'] = ";
param += JSON.stringify(params[i], null, '\t');
param += ";";
param += "\n";
}
param += "\n";
var methodCall = "// Make a request to the Google Cloud Storage API \n";
methodCall += "var request = gapi.client." + method + "(params);";
return objConstruction + param + methodCall;
}
/**
* Executes your Google Cloud Storage request object and, subsequently,
* inserts the response into the page.
* @param {string} request A Google Cloud Storage request object issued
* from the Google Cloud Storage JavaScript client library.
* @param {string} apiRequestName The name of the example API request.
*/
function executeRequest(request, apiRequestName) {
request.execute(function(resp) {
console.log(resp);
var apiRequestNode = document.createElement('div');
apiRequestNode.id = apiRequestName;
var apiRequestNodeHeader = document.createElement('h2');
apiRequestNodeHeader.innerHTML = apiRequestName;
var apiRequestExplanationNode = document.createElement('div');
apiRequestExplanationNode.id = apiRequestName + 'RequestExplanation';
var apiRequestExplanationNodeHeader = document.createElement('h3');
apiRequestExplanationNodeHeader.innerHTML = 'API Request Explanation';
apiRequestExplanationNode.appendChild(apiRequestExplanationNodeHeader);
var apiRequestExplanationEntry = document.createElement('p');
apiRequestExplanationEntry.innerHTML =
listApiRequestExplanations[apiRequestName];
apiRequestExplanationNode.appendChild(apiRequestExplanationEntry);
apiRequestNode.appendChild(apiRequestNodeHeader);
apiRequestNode.appendChild(apiRequestExplanationNode);
var apiRequestCodeSnippetNode = document.createElement('div');
apiRequestCodeSnippetNode.id = apiRequestName + 'CodeSnippet';
var apiRequestCodeSnippetHeader = document.createElement('h3');
apiRequestCodeSnippetHeader.innerHTML = 'API Request Code Snippet';
apiRequestCodeSnippetNode.appendChild(apiRequestCodeSnippetHeader);
var apiRequestCodeSnippetEntry = document.createElement('pre');
//If the selected API command is not 'insertObject', pass the request
//paramaters to the getCodeSnippet method call as 'request.wc.wc.params'
//else pass request paramaters as 'request.wc.wc'
/* if (apiRequestName != 'insertObject') {
apiRequestCodeSnippetEntry.innerHTML =
getCodeSnippet(request.wc.wc.method, request.wc.wc.params);
//Selected API Command is not 'insertObject'
//hide insert object button
filePicker.style.display = 'none';
} else {
apiRequestCodeSnippetEntry.innerHTML =
getCodeSnippet(request.wc.wc.method, request.wc.wc);
}*/
apiRequestCodeSnippetNode.appendChild(apiRequestCodeSnippetEntry);
apiRequestNode.appendChild(apiRequestCodeSnippetNode);
var apiResponseNode = document.createElement('div');
apiResponseNode.id = apiRequestName + 'Response';
var apiResponseHeader = document.createElement('h3');
apiResponseHeader.innerHTML = 'API Response';
apiResponseNode.appendChild(apiResponseHeader);
var apiResponseEntry = document.createElement('pre');
apiResponseEntry.innerHTML = JSON.stringify(resp, null, ' ');
apiResponseNode.appendChild(apiResponseEntry);
apiRequestNode.appendChild(apiResponseNode);
var content = document.getElementById('main-content');
content.appendChild(apiRequestNode);
});
}
/**
* Set required API keys and check authentication status.
*/
function handleClientLoad() {
gapi.client.setApiKey(apiKey);
window.setTimeout(checkAuth, 1);
}
/**
* Authorize Google Cloud Storage API.
*/
function checkAuth() {
gapi.auth.authorize({
client_id: clientId,
scope: scopes,
immediate: true
}, handleAuthResult);
}
/**
* Handle authorization.
*/
function handleAuthResult(authResult) {
var authorizeButton = document.getElementById('authorize-button');
if (authResult && !authResult.error) {
authorizeButton.style.visibility = 'hidden';
initializeApi();
filePicker.onchange = insertObject;
} else {
authorizeButton.style.visibility = '';
authorizeButton.onclick = handleAuthClick;
}
}
/**
* Handle authorization click event.
*/
function handleAuthClick(event) {
gapi.auth.authorize({
client_id: clientId,
scope: scopes,
immediate: false
}, handleAuthResult);
return false;
}
/**
* Load the Google Cloud Storage API.
*/
function initializeApi() {
gapi.client.load('storage', API_VERSION);
}
/**
* Driver for sample application.
*/
$(window)
.bind('load', function() {
addSelectionSwitchingListeners();
handleClientLoad();
});
</script>
</head>
<body>
<!--Add a button for the user to click to initiate auth sequence -->
<button id="authorize-button" style="visibility: hidden">Authorize</button>
<header>
<h1>Google Cloud Storage JavaScript Client Library Application</h1>
</header>
<label id="api-label">Try a sample API call!</label>
<select id="api-selection-options">
<option value="null">
Please select an example API call from the dropdown menu
</option>
<option value="listBuckets">
List Buckets
</option>
<option value="insertBucket">
Insert Bucket
</option>
<option value="getBucket">
Get Bucket
</option>
<option value="getBucketAccessControls">
Get Bucket Access Controls
</option>
<option value="insertBucketAccessControls">
Insert Bucket Access Controls
</option>
<option value="listBucketsAccessControls">
List Buckets Access Control List
</option>
<option value="insertObject">
Insert Object
</option>
<option value="listObjects">
List Objects
</option>
<option value="getObjectAccessControls">
Get Object Access Controls
</option>
<option value="insertObjectAccessControls">
Insert Object Access Controls
</option>
<option value="listObjectsAccessControls">
List Objects Access Control List
</option>
<option value="deleteObject">
Delete Object
</option>
<option value="deleteBucket">
Delete Bucket
</option>
</select>
<br/>
<input type="file" id="filePicker" style="display: none" />
<div id="main-content">
</div>
</body>
</html>
以下是上传文件的函数，完全受到上面例子的启发。请注意，它使用JavaScript客户端库与Google API（gapi）交互，这意味着您可以通过Google帐户进行身份验证来保护上传(https://developers.google.com/api-client-library/javascript/start/start-js)。
function uploadFile(fileData, bucket) {
var boundary = '-------314159265358979323846';
var delimiter = "\r\n--" + boundary + "\r\n";
var close_delim = "\r\n--" + boundary + "--";
var reader = new FileReader();
reader.readAsBinaryString(fileData);
reader.onload = function (e) {
var contentType = fileData.type || 'application/octet-stream';
var metadata = {
'name': fileData.name,
'mimeType': contentType
};
var base64Data = btoa(reader.result);
var multipartRequestBody =
delimiter +
'Content-Type: application/json\r\n\r\n' +
JSON.stringify(metadata) +
delimiter +
'Content-Type: ' + contentType + '\r\n' +
'Content-Transfer-Encoding: base64\r\n' +
'\r\n' +
base64Data +
close_delim;
var request = gapi.client.request({
'path': '/upload/storage/v1/b/' + bucket + '/o',
'method': 'POST',
'params': {'uploadType': 'multipart'},
'headers': {
'Content-Type': 'multipart/mixed; boundary="' + boundary + '"'
},
'body': multipartRequestBody
});
try {
request.execute(function (resp) {
if (resp.hasOwnProperty("error")) {
//Treat Error
} else {
//Treat Success
}
});
}
catch (e) {
//Treat Error
}
};
}
最后，您可以使用云存储的对象更改通知来调用App引擎中的任务。 您可以传递桶和文件名，并通过App引擎处理刚上传的文件。 https://cloud.google.com/storage/docs/object-change-notification
- Renaud Tarnec
10
您需要查看文档和代码示例，因为有许多地方可以找到与云存储交互的示例，无论是客户端还是服务器端。 - Nick
但是有一个问题。当我运行您的代码时，用户需要授权。我需要跳过它，让用户上传图片吗？ - user2354982
@user2354982 不确定你遇到了什么问题：你想授权用户还是不想授权？如果你想的话，就像我说的“你可以通过谷歌账户进行身份验证来保护上传（https://developers.google.com/api-client-library/javascript/start/start-js）”。如果你不想，就将这部分停用即可。 - Renaud Tarnec
我需要的是：从我的网站上传图像到Google云存储，无需授权。有一个完整的示例可以做到这一点吗？ - user2354982
我的回答正是如此... 你试过了吗？你研究过了吗？就像我告诉你的那样，你可以从谷歌示例中删除身份验证部分，这很容易。你只需要花时间“深入代码”即可。 - Renaud Tarnec
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