MetadataWriter.java

package gov.loc.repository.bagit.writer;

import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.util.ResourceBundle;
import java.util.AbstractMap.SimpleImmutableEntry;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import gov.loc.repository.bagit.domain.Metadata;
import gov.loc.repository.bagit.domain.Version;

/**
 * Responsible for writing out the bag {@link Metadata} to the filesystem
 */
public final class MetadataWriter {
  private static final Logger logger = LoggerFactory.getLogger(MetadataWriter.class);
  private static final Version VERSION_0_95 = new Version(0, 95);
  private static final ResourceBundle messages = ResourceBundle.getBundle("MessageBundle");

  private MetadataWriter(){
    //intentionall left empty
  }
  
  /**
   * Write the bag-info.txt (or package-info.txt) file to the specified outputDir with specified encoding (charsetName)
   * 
   * @param metadata the key value pair info in the bag-info.txt file
   * @param version the version of the bag you are writing
   * @param outputDir the root of the bag
   * @param charsetName the name of the encoding for the file
   * 
   * @throws IOException if there was a problem writing a file
   */
  public static void writeBagMetadata(final Metadata metadata, final Version version, final Path outputDir, final Charset charsetName) throws IOException{
    Path bagInfoFilePath = outputDir.resolve("bag-info.txt");
    if(version.isSameOrOlder(VERSION_0_95)){
      bagInfoFilePath = outputDir.resolve("package-info.txt");
    }
    logger.debug(messages.getString("writing_metadata_to_path"), bagInfoFilePath.getFileName(), outputDir);

    Files.deleteIfExists(bagInfoFilePath);
    final StringBuilder lines = new StringBuilder();
    
    for(final SimpleImmutableEntry<String, String> entry : metadata.getAll()){
      final String line = entry.getKey() + ": " + entry.getValue() + System.lineSeparator();
      lines.append(line);
    }
    
    logger.debug(messages.getString("writing_line_to_file"), lines.toString(), bagInfoFilePath);
    Files.write(bagInfoFilePath, lines.toString().getBytes(charsetName), 
        StandardOpenOption.APPEND, StandardOpenOption.CREATE);
  }
}