我正在尝试将文件上传到Google云端存储。我的Servlet代码是
public class UploadFile extends HttpServlet {
private final String BUCKET = "XXXXXXXXX";
private boolean isMultipart;
private String filePath;
private int maxFileSize = 5 * 1024 * 1024;
private int maxMemSize = 5 * 1024 * 1024;
private File file ;
public void init( ){
// Get the file location where it would be stored.
filePath =
getServletContext().getInitParameter("file-upload");
}
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, java.io.IOException {
// Check that we have a file upload request
isMultipart = ServletFileUpload.isMultipartContent(request);
response.setContentType("text/html");
java.io.PrintWriter out = response.getWriter( );
if( !isMultipart ){
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet upload</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>No file uploaded</p>");
out.println("</body>");
out.println("</html>");
return;
}
DiskFileItemFactory factory = new DiskFileItemFactory();
// maximum size that will be stored in memory
factory.setSizeThreshold(maxMemSize);
// Location to save data that is larger than maxMemSize.
factory.setRepository(new File("/temp/image/"));
// Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload(factory);
// maximum file size to be uploaded.
upload.setSizeMax( maxFileSize );
try{
// Parse the request to get file items.
List fileItems = upload.parseRequest(request);
// Process the uploaded file items
Iterator i = fileItems.iterator();
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet upload</title>");
out.println("</head>");
out.println("<body>");
while ( i.hasNext () )
{
FileItem fi = (FileItem)i.next();
if ( !fi.isFormField () )
{
// Get the uploaded file parameters
String fieldName = fi.getFieldName();
String fileName = fi.getName();
String contentType = fi.getContentType();
boolean isInMemory = fi.isInMemory();
long sizeInBytes = fi.getSize();
// Write the file
if( fileName.lastIndexOf("\\") >= 0 ){
file = new File( filePath +
fileName.substring( fileName.lastIndexOf("\\"))) ;
}else{
file = new File( filePath +
fileName.substring(fileName.lastIndexOf("\\")+1)) ;
}
String path = Events.uploadFile ( fileName, "image/*", file, BUCKET );
// fi.write( file ) ;
out.println("Uploaded Filename: " + fileName + "<br>"+ " File Path:"+ path);
}
}
out.println("</body>");
out.println("</html>");
}catch(Exception ex) {
System.out.println(ex);
}
}
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, java.io.IOException {
throw new ServletException("GET method used with " +
getClass( ).getName( )+": POST method required.");
}
}
的web.xml
<servlet>
<servlet-name>UploadFile</servlet-name>
<servlet-class>XXXXXXXXXX.UploadFile</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UploadFile</servlet-name>
<url-pattern>/uploadManager/UploadFile</url-pattern> //Based on your original URL
</servlet-mapping>
fileUpload函数将文件保存到GCS
public static String uploadFile ( String name, String contentType, File file, String bucketName )
throws IOException, GeneralSecurityException
{
InputStreamContent contentStream = new InputStreamContent ( contentType, new FileInputStream ( file ) );
// Setting the length improves upload performance
contentStream.setLength ( file.length () );
StorageObject objectMetadata = new StorageObject ()
// Set the destination object name
.setName ( name )
// Set the access control list to publicly read-only
.setAcl ( Arrays.asList ( new ObjectAccessControl ().setEntity ( "allUsers" ).setRole ( "READER" ) ) );
// Do the insert
Storage client = StorageFactory.getService ();
Storage.Objects.Insert insertRequest = client.objects ().insert ( bucketName, objectMetadata, contentStream );
insertRequest.execute ();
return "https://storage.cloud.google.com/" + BUCKET + "/" + file.getName ();
}
但是当我尝试使用某些API测试客户端进行测试时，它会出错
org.apache.commons.fileupload.FileUploadException: the request was rejected because no multipart boundary was found
进一步将其与Angular中的UI集成并在本地测试后，我面临这个问题
Cross-Origin Request Blocked Reason: CORS header 'Access-Control-Allow-Origin' missing
我尝试解决此问题，但未找到与google appengine相对应的解决方案。
最初我尝试通过此代码上传图片，但在不久的将来，相同的代码将用于将.pdf和.html文件上传到GCS。
供参考： 我正在使用Google Endpoints满足客户端的其他数据通信需求。 Client End是Angular中的webapp构建，但它将扩展到android和ios。
任何帮助将不胜感激。
谢谢
更新2016年1月8日
现在我收到服务器上的文件，但我不知道在将文件发送到Google云端存储之前我必须暂时保存该文件。在
中存储文件war\WEB-INI\
我面临的例外是
java.security.AccessControlException: access denied ("java.io.FilePermission" "\war\WEB-INI\profile.png" "read")
答案 0 :(得分：4)
最后，我可以通过appengine将文件从客户端上传到Google云端存储。
我认为在执行这些步骤之前，您已准备好以下事项
第1步：制作这样的Servlet
package XXXXXXXXX;
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.util.Arrays;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.google.api.client.http.InputStreamContent;
import com.google.api.services.storage.Storage;
import com.google.api.services.storage.model.ObjectAccessControl;
import com.google.api.services.storage.model.StorageObject;
import XXXXXXXXXXXXX.StorageFactory;
//@author Umesh Chauhan
/**
* Save File to GCS
*
* @param fileName File Name with format
* @header Content-Type "*/*"
* @return file path
* @throws Exception Any Error during upload
*/
public class UploadFile extends HttpServlet
{
private static final long serialVersionUID = 1L;
private final String BUCKET = "YOUR BUCKET NAME";
private int maxFileSize = 6 * 1024 * 1024;
@Override
protected void doOptions ( HttpServletRequest req, HttpServletResponse resp ) throws ServletException, IOException
{
// pre-flight request processing
resp.setHeader ( "Access-Control-Allow-Origin", "*" );
resp.setHeader ( "Access-Control-Allow-Methods", "*" );
resp.setHeader ( "Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept" );
}
@Override
public void doPost ( HttpServletRequest request, HttpServletResponse response )
throws ServletException, java.io.IOException
{
try
{
String path = uploadFile ( request.getParameter ( "fileName" ), request.getContentType (),
request.getInputStream (), BUCKET, request.getInputStream ().available () );
// Sending Response
response.setStatus ( HttpServletResponse.SC_OK );
response.getWriter ().write ( path );
response.getWriter ().flush ();
response.getWriter ().close ();
}
catch ( GeneralSecurityException e )
{
e.printStackTrace ();
}
}
public String uploadFile ( String name, String contentType, InputStream input, String bucketName,
int contentLength ) throws IOException, GeneralSecurityException
{
InputStreamContent contentStream = new InputStreamContent ( contentType, input );
if ( contentLength < maxFileSize )
{
// It is done Automatically.
/*
* // Setting the length improves upload performance
* contentStream.setLength ( contentLength );
*/
StorageObject objectMetadata = new StorageObject ()
// Set the destination object name
.setName ( name )
// Set the access control list to publicly read-only
.setAcl ( Arrays.asList (
new ObjectAccessControl ().setEntity ( "allUsers" ).setRole ( "READER" ) ) );
// Do the insert
Storage client = StorageFactory.getService ();
Storage.Objects.Insert insertRequest = client.objects ()
.insert ( bucketName, objectMetadata, contentStream );
insertRequest.execute ();
return "https://storage.cloud.google.com/" + BUCKET + "/" + name;
}
else
{
throw new GeneralSecurityException ( "File size canot be more then 6 MB !" );
}
}
public void doGet ( HttpServletRequest request, HttpServletResponse response )
throws ServletException, java.io.IOException
{
throw new ServletException ( "GET method used with " + getClass ().getName () + ": POST method required." );
}
}
第2步：您的存储工厂
package XXXXXXXXXXXX;
import java.io.IOException;
import java.net.URL;
import java.security.GeneralSecurityException;
import java.util.Collection;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.storage.Storage;
import com.google.api.services.storage.StorageScopes;
//@author Umesh Chauhan
public class StorageFactory
{
private static Storage instance = null;
public static synchronized Storage getService () throws IOException, GeneralSecurityException
{
if ( instance == null )
{
instance = buildService ();
}
return instance;
}
private static Storage buildService () throws IOException, GeneralSecurityException
{
HttpTransport transport = GoogleNetHttpTransport.newTrustedTransport ();
JsonFactory jsonFactory = new JacksonFactory ();
GoogleCredential credential = GoogleCredential.fromStream (
new URL ( "HERE GOES THE URL FOR YOUR SERVICE ACCOUNT JSON - I USED GOOGLE DRIVE DIRECT DOWNLOAD LINK TO MY JSON FILE" )
.openStream () );
// Depending on the environment that provides the default credentials
// (for
// example: Compute Engine, App Engine), the credentials may require us
// to
// specify the scopes we need explicitly. Check for this case, and
// inject
// the Cloud Storage scope if required.
if ( credential.createScopedRequired () )
{
Collection<String> scopes = StorageScopes.all ();
credential = credential.createScoped ( scopes );
}
return new Storage.Builder ( transport, jsonFactory, credential ).setApplicationName ( "YOUR PROJECT NAME" ).build ();
}
}
第3步：更新web.xml
<servlet>
<servlet-name>UploadFile</servlet-name>
<servlet-class>PACKAGE.UploadFile</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UploadFile</servlet-name>
<url-pattern>/uploadManager/UploadFile</url-pattern> //Based on your original URL
</servlet-mapping>
答案 1 :(得分：2)
以下是根据docs
上传到存储空间的正确方法import com.google.appengine.tools.cloudstorage.*;
public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
String buffer = "the data to be saved in GCS bla bla";
GcsFileOptions instance = GcsFileOptions.getDefaultInstance();
GcsFilename fileName = new GcsFilename("bucketName", "fileName");
GcsOutputChannel outputChannel;
gcsService.createOrReplace(fileName, instance, ByteBuffer.wrap(buffer.getBytes()));
}
您将找到完整的代码here
答案 2 :(得分：1)
首先，您需要在飞行前请求处理中解决CORS问题，您需要在后端执行：在Google App Engine上通过添加doOptions方法完成：
@Override
protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
{
resp.setHeader("Access-Control-Allow-Origin", "*");
resp.setHeader("Access-Control-Allow-Methods", "*");
resp.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
}
然后您需要确保使用Content-Type: multipart/form-data这样的标头发送请求，否则您的文件将被错误编码。在angular2请求标头中，您的帖子请求中设置为第三个（可选）参数，如：
let headers = new Headers();
headers.append('content-type', 'multipart/form-data');
http.post(url, body, {
headers:headers
})
答案 3 :(得分：1)
对不起，这并没有直接解决你的问题，但无论如何我想指出来。我建议使用您的一个正常端点生成一个临时上传URL，Angular客户端可以使用该URL直接将文件发送到云存储，而无需通过您的应用程序。一种方法是通过blobstore API，如here所述。您可以按照here所述，通过该API上传到云端存储（在同一页面的下方）。
这会减少您在服务器上所需的上传代码量，不受GAE请求的32MB限制，并且符合Google的建议（如上文文档链接所示）。
答案 4 :(得分：1)
在本地运行gcloud auth application-default login命令时
见authentication
import com.google.cloud.storage.*;
public static void upload(String bucketName, String fileId, String content) throws IOException {
Storage storage = StorageOptions.newBuilder().build().getService();
BlobInfo fileInfo = BlobInfo.newBuilder(bucketName, fileId)
.build();
InputStream fileIS = IOUtils.toInputStream(content, "UTF-8");
storage.create(fileInfo, fileIS);
}