Java File S3 Upload

How it works

1. Create a bucket on Amazon S3 and set the CORS for it.
2. Code computes the Amazon S3 signature on server side.
3. The editor initializes with the fileUploadToS3 option.
4. Uploaded files go directly to the S3 bucket without passing through the server.

Jump to Complete Example

Create a S3 Bucket

Amazon explains in detail on the URL below how to create a bucket and set a region for it. If you have any troubles with creating it, please contact Amazon for getting it set up.

http://docs.aws.amazon.com/AmazonS3/latest/gsg/CreatingABucket.html

Set CORS on the S3 Bucket

Cross-origin resource sharing (CORS) tells Amazon from which domains to accept requests and what kind of requests. For a detailed explanation of how that works, refer to the Amazon CORS Documentation.

The following example shows the recomended configuration, remember to replace ALLOWED_URL with the URL of the page where you are using editor:

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<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
    <CORSRule>
        <AllowedOrigin>ALLOWED_URL</AllowedOrigin>
        <AllowedMethod>GET</AllowedMethod>
        <AllowedMethod>POST</AllowedMethod>
        <AllowedMethod>PUT</AllowedMethod>
        <MaxAgeSeconds>3000</MaxAgeSeconds>
        <AllowedHeader>*</AllowedHeader>
    </CORSRule>
</CORSConfiguration>

Compute Signature

To get the file uploaded to S3, it is necessary to compute a signature using the AWS access key ID and AWS secret access key and provide it together with the upload request. The editor .NET SDK comes with methods to compute the S3 signature using the V4 signing algorithm that works with buckets created on any of the S3 regions.

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S3Config config = new S3Config();

// The name of your bucket.
config.bucket = 'bucket-name';

// S3 region. If you are using the default us-east-1, it this can be ignored.
config.region = 'eu-west-1';

// The folder where to upload the images.
config.keyStart = 'uploads';

// File access.
config.acl = 'public-read';

// AWS keys.
config.accessKey = YOUR_AWS_ACCESS_KEY;
config.secretKey = YOUR_AWS_SECRET_KEY;

// Compute the signature.
Map<Object, Object> hash = S3.getHash(config);

Initialize the javascript editor

To upload images to Amazon S3, set the fileUploadToS3 option on initialization. The editor Java SDK computes the hash required for this as the response of the FroalaEditor.S3.GetHash method.

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<script>
  $.get( "/amazon_hash", {})
  .done(function( data ) {
      $('.selector').froalaEditor({
          fileUploadToS3: data
      })
  });
</script>

Complete Example

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<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
    <CORSRule>
        <AllowedOrigin>ALLOWED_URL</AllowedOrigin>
        <AllowedMethod>GET</AllowedMethod>
        <AllowedMethod>POST</AllowedMethod>
        <AllowedMethod>PUT</AllowedMethod>
        <MaxAgeSeconds>3000</MaxAgeSeconds>
        <AllowedHeader>*</AllowedHeader>
    </CORSRule>
</CORSConfiguration>

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package com.froala.examples.servlets;

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

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

import com.froala.editor.S3;
import com.froala.editor.s3.S3Config;
import com.google.gson.Gson;

/**
 * Servlet implementation class AmazonHash
 */
@WebServlet("/amazon_hash")
public class AmazonHash extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public AmazonHash() {
        super();
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        Map<Object, Object> hash;
        S3Config config = new S3Config();
        // The name of your bucket.
        config.bucket = 'bucket-name';

        // S3 region. If you are using the default us-east-1, it this can be ignored.
        config.region = 'eu-west-1';

        // The folder where to upload the images.
        config.keyStart = 'uploads';

        // File access.
        config.acl = 'public-read';

        // AWS keys.
        config.accessKey = YOUR_AWS_ACCESS_KEY;
        config.secretKey = YOUR_AWS_SECRET_KEY;

        try {
            // Compute the signature.
            hash = S3.getHash(config);
        } catch (Exception e) {
            e.printStackTrace();
            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }

        String jsonResponseData = new Gson().toJson(hash);
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        response.getWriter().write(jsonResponseData);
    }

}

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<script>
  $.get( "/amazon_hash", {})
  .done(function( data ) {
      $('.selector').froalaEditor({
          fileUploadToS3: data
      })
  });
</script>