将图像从 android 客户端存储到 Blobstore,并检索 blobkey 并上传 url 以存储在 Datastore 中.- GAE [英] Store image to Blobstore from android client and retrieve blobkey and upload url to store in Datastore. - GAE
问题描述
在我的 Android 应用程序中,我想将图像上传到 Blobstore,然后检索上传 url 和图像的 Blobkey,以便我可以将 Blobkey 存储在 DataStore 中.
In my Android application, I want to upload image to the Blobstore, then retrieve an Upload url and the image's Blobkey, so I can store the Blobkey in the DataStore.
我已经尝试过这段代码,但我的图片没有上传:
I've tried this code, but my image isn't uploading:
Servlet(返回上传地址)
Servlet (Return upload url)
BlobstoreService blobstoreService = BlobstoreServiceFactory
.getBlobstoreService();
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
UploadOptions uploadOptions = UploadOptions.Builder
.withGoogleStorageBucketName("photobucket11")
.maxUploadSizeBytes(1048576);
String blobUploadUrl = blobstoreService.createUploadUrl("/upload",
uploadOptions);
// String blobUploadUrl = blobstoreService.createUploadUrl("/uploaded");
resp.setStatus(HttpServletResponse.SC_OK);
resp.setContentType("text/plain");
PrintWriter out = resp.getWriter();
out.print(blobUploadUrl);
}
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
doGet(req, resp);
}
代码:安卓客户端
Bitmap bmp = BitmapFactory.decodeFile(imagePath);
ByteArrayOutputStream out = new ByteArrayOutputStream();
bmp.compress(CompressFormat.JPEG, 75, out);
byte[] imgByte = out.toByteArray();
String encodedImage = Base64.encodeToString(imgByte,
Base64.DEFAULT);
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(
"app-url/ImgUpload");
HttpResponse response = httpClient.execute(httpGet);
HttpEntity urlEntity = response.getEntity();
InputStream in = urlEntity.getContent();
String str = "";
while (true) {
int ch = in.read();
if (ch == -1)
break;
str += (char) ch;
}
这将以 /_ah/upload/akjdhjahdjaudshgaajsdhjsdh
的形式返回上传 url,我可以用它来存储图像.
This will return upload url in form of /_ah/upload/akjdhjahdjaudshgaajsdhjsdh
which I can use to store the image.
此代码使用 url 来存储图像:
This code uses the url to store the image:
httpClient = new DefaultHttpClient();
HttpPost postRequest = new HttpPost(str);
ByteArrayBody bab = new ByteArrayBody(imgByte, "forest.jpg");
MultipartEntity reqEntity = new MultipartEntity(
HttpMultipartMode.BROWSER_COMPATIBLE);
reqEntity.addPart("uploaded", bab);
reqEntity.addPart("photoCaption", new StringBody("sfsdfsdf"));
postRequest.setEntity(reqEntity);
response = httpClient.execute(postRequest);
BufferedReader reader = new BufferedReader(
new InputStreamReader(
response.getEntity().getContent(), "UTF-8"));
String sResponse;
StringBuilder s = new StringBuilder();
while ((sResponse = reader.readLine()) != null) {
s = s.append(sResponse);
}
这里,如果我检查字符串 s
的值,它会显示 null
.这意味着它返回一个空响应.我不知道这段代码有什么问题.请指导我解决这个问题.
Here, if I check value of the String s
, it shows null
. That means it is returning a null response. I don't know what the problem is with this code. Please guide me to solve this problem.
推荐答案
经过多次尝试,我解决了这个问题.要将图像存储在 blobstore 中,首先 android 需要向 servlet 发出请求,servlet 将生成上传 url :
After many tries i solved this problem. To store image in blobstore, first android needs to make request to servlet which will generate upload url :
Android 客户端:它会请求生成 url 并从 servlet 获取 url
Android client : It will request to generate url and gets url from servlet
HttpClient httpClient = new DefaultHttpClient();
//This will invoke "ImgUpload servlet
HttpGet httpGet = new HttpGet("my-app-url/ImgUpload");
HttpResponse response = httpClient.execute(httpGet);
HttpEntity urlEntity = response.getEntity();
InputStream in = urlEntity.getContent();
String str = "";
while (true) {
int ch = in.read();
if (ch == -1)
break;
str += (char) ch;
}
ImgUpload.java - 生成 url 并向客户端发送响应的 Servlet
ImgUpload.java - Servlet to generate url and sends response to client
BlobstoreService blobstoreService = BlobstoreServiceFactory
.getBlobstoreService();
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
//"uploaded" is another servlet which will send UploadUrl and blobkey to android client
String blobUploadUrl = blobstoreService.createUploadUrl("/uploaded");
resp.setStatus(HttpServletResponse.SC_OK);
resp.setContentType("text/plain");
PrintWriter out = resp.getWriter();
out.print(blobUploadUrl);
}
在android客户端,写下面的代码上传图像到上面servlet返回的响应.
In android client,write below code upload image to returned response from above servlet.
//Save image to generated url
HttpPost httppost = new HttpPost(str);
File f = new File(imagePath);
FileBody fileBody = new FileBody(f);
MultipartEntity reqEntity = new MultipartEntity();
reqEntity.addPart("file", fileBody);
httppost.setEntity(reqEntity);
response = httpClient.execute(httppost); //Here "uploaded" servlet is automatically invoked
urlEntity = response.getEntity(); //Response will be returned by "uploaded" servlet in JSON format
in = urlEntity.getContent();
str = "";
while (true) {
int ch = in.read();
if (ch == -1)
break;
str += (char) ch;
}
JSONObject resultJson = new JSONObject(str);
String blobKey = resultJson.getString("blobKey");
String servingUrl = resultJson.getString("servingUrl");
uploaded.java- servlet 返回图片的 Uploadurl 和 Blobkey
uploaded.java- servlet which returns Uploadurl and Blobkey of image
BlobstoreService blobstoreService = BlobstoreServiceFactory
.getBlobstoreService();
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
try {
List<BlobKey> blobs = blobstoreService.getUploads(req).get("file");
BlobKey blobKey = blobs.get(0);
ImagesService imagesService = ImagesServiceFactory
.getImagesService();
ServingUrlOptions servingOptions = ServingUrlOptions.Builder
.withBlobKey(blobKey);
String servingUrl = imagesService.getServingUrl(servingOptions);
resp.setStatus(HttpServletResponse.SC_OK);
resp.setContentType("application/json");
JSONObject json = new JSONObject();
json.put("servingUrl", servingUrl);
json.put("blobKey", blobKey.getKeyString());
PrintWriter out = resp.getWriter();
out.print(json.toString());
out.flush();
out.close();
} catch (JSONException e) {
e.printStackTrace();
}
}
这篇关于将图像从 android 客户端存储到 Blobstore,并检索 blobkey 并上传 url 以存储在 Datastore 中.- GAE的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!