// [START uploading_a_blob_1]
<body>
    <form action="<%= blobstoreService.createUploadUrl("/upload") %>" method="post" enctype="multipart/form-data">
        <input type="file" name="myFile">
        <input type="submit" value="Submit">
    </form>
</body>
// [END uploading_a_blob_1]

// [START uploading_a_blob_2]
Map<String, List<BlobKey>> blobs = blobstoreService.getUploads(req);
List<BlobKey> blobKeys = blobs.get("myFile");

if (blobKeys == null || blobKeys.isEmpty()) {
    res.sendRedirect("/");
} else {
    res.sendRedirect("/serve?blob-key=" + blobKeys.get(0).getKeyString());
}
// [END uploading_a_blob_2]

// [START serving_a_blob]
public void doGet(HttpServletRequest req, HttpServletResponse res)
    throws IOException {
        BlobKey blobKey = new BlobKey(req.getParameter("blob-key"));
        blobstoreService.serve(blobKey, res);
// [END serving_a_blob]

// [START complete_sample_application]
// file Upload.java

import java.io.IOException;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.appengine.api.blobstore.BlobKey;
import com.google.appengine.api.blobstore.BlobstoreService;
import com.google.appengine.api.blobstore.BlobstoreServiceFactory;

public class Upload extends HttpServlet {
    private BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();

    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException {

        Map<String, List<BlobKey>> blobs = blobstoreService.getUploads(req);
        List<BlobKey> blobKeys = blobs.get("myFile");

        if (blobKeys == null || blobKeys.isEmpty()) {
            res.sendRedirect("/");
        } else {
            res.sendRedirect("/serve?blob-key=" + blobKeys.get(0).getKeyString());
        }
    }
}

// file Serve.java

import java.io.IOException;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.appengine.api.blobstore.BlobKey;
import com.google.appengine.api.blobstore.BlobstoreService;
import com.google.appengine.api.blobstore.BlobstoreServiceFactory;

public class Serve extends HttpServlet {
    private BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();

    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse res)
        throws IOException {
            BlobKey blobKey = new BlobKey(req.getParameter("blob-key"));
            blobstoreService.serve(blobKey, res);
        }
}


// file index.jsp

<%@ page import="com.google.appengine.api.blobstore.BlobstoreServiceFactory" %>
<%@ page import="com.google.appengine.api.blobstore.BlobstoreService" %>

<%
    BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();
%>


<html>
    <head>
        <title>Upload Test</title>
    </head>
    <body>
        <form action="<%= blobstoreService.createUploadUrl("/upload") %>" method="post" enctype="multipart/form-data">
            <input type="text" name="foo">
            <input type="file" name="myFile">
            <input type="submit" value="Submit">
        </form>
    </body>
</html>

// web.xml

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns="http://java.sun.com/xml/ns/javaee"
   xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
   http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">

  <servlet>
    <servlet-name>Upload</servlet-name>
    <servlet-class>Upload</servlet-class>
  </servlet>
  
  <servlet>
    <servlet-name>Serve</servlet-name>
    <servlet-class>Serve</servlet-class>
  </servlet>
 
  <servlet-mapping>
    <servlet-name>Upload</servlet-name>
    <url-pattern>/upload</url-pattern>
  </servlet-mapping>

  <servlet-mapping>
    <servlet-name>Serve</servlet-name>
    <url-pattern>/serve</url-pattern>
  </servlet-mapping>
  
</web-app>
// [END complete_sample_application]

// [START writing_files_to_the_Blobstore]
// Get a file service
FileService fileService = FileServiceFactory.getFileService();

// Create a new Blob file with mime-type "text/plain"
AppEngineFile file = fileService.createNewBlobFile("text/plain");

// Open a channel to write to it
boolean lock = false;
FileWriteChannel writeChannel = fileService.openWriteChannel(file, lock);

// Different standard Java ways of writing to the channel
// are possible. Here we use a PrintWriter:
PrintWriter out = new PrintWriter(Channels.newWriter(writeChannel, "UTF8"));
out.println("The woods are lovely dark and deep.");
out.println("But I have promises to keep.");

// Close without finalizing and save the file path for writing later
out.close();
String path = file.getFullPath();

// Write more to the file in a separate request:
file = new AppEngineFile(path);

// This time lock because we intend to finalize
lock = true;
writeChannel = fileService.openWriteChannel(file, lock);

// This time we write to the channel directly
writeChannel.write(ByteBuffer.wrap
          ("And miles to go before I sleep.".getBytes()));

// Now finalize
writeChannel.closeFinally();

// Later, read from the file using the Files API
lock = false; // Let other people read at the same time
FileReadChannel readChannel = fileService.openReadChannel(file, false);

// Again, different standard Java ways of reading from the channel.
BufferedReader reader =
        new BufferedReader(Channels.newReader(readChannel, "UTF8"));
     String line = reader.readLine();
// line = "The woods are lovely dark and deep."

readChannel.close();

// Now read from the file using the Blobstore API
BlobKey blobKey = fileService.getBlobKey(file);
BlobstoreService blobStoreService = BlobstoreServiceFactory.getBlobstoreService();
String segment = new String(blobStoreService.fetchData(blobKey, 30, 40));
// [END writing_files_to_the_Blobstore]