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Registry API Service contributing to the PDS Federated Search API

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package gov.nasa.pds.api.registry.model;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Base64;
import java.util.zip.InflaterInputStream;

/**
 * Utility class to extract BLOBs stored in DB
 * 
 * @author karpenko
 */
public class BlobUtil {
  public static final String JSON_BLOB_PROPERTY = "ops:Label_File_Info/ops:json_blob";
  public static final String XML_BLOB_PROPERTY = "ops:Label_File_Info/ops:blob";

  /**
   * Decompress base64 encoded BLOB.
   * 
   * @param blob Base64 encoded compressed BLOB
   * @return Original BLOB value as a string
   * @throws Exception an exception
   */
  public static String blobToString(String blob) throws Exception {
    byte[] data = Base64.getDecoder().decode(blob);
    return blobToString(data);
  }

  /**
   * Decompress binary BLOB.
   * 
   * @param blob compressed BLOB
   * @return Original BLOB value as a string
   * @throws Exception an exception
   */
  public static String blobToString(byte[] blob) throws Exception {
    ByteArrayInputStream is = new ByteArrayInputStream(blob);
    // Decompress ("inflate") the BLOB
    InflaterInputStream source = new InflaterInputStream(is);

    ByteArrayOutputStream dest = new ByteArrayOutputStream();
    copy(source, dest);
    dest.close();

    return dest.toString("utf-8");
  }

  /**
   * Copy data from input to output stream
   * 
   * @param source source stream
   * @param dest destination stream
   * @throws Exception an exception
   */
  private static void copy(InputStream source, OutputStream dest) throws Exception {
    byte[] buf = new byte[1024];

    int count = 0;
    while ((count = source.read(buf)) >= 0) {
      dest.write(buf, 0, count);
    }
  }

}