Exporting an object to a ZIP file

Question

I have my own type of object, which implements Serializable. Here I have one called "extendedFormat" (not a terribly helpful name, yes, I know). I'm writing it out to a file like so:

try {
 // is this the best way to do this????????
 // this seems like too many streams perhaps.
 // like maybe this is now a river
 File file = new File("C:/temp/tempExport.bef");
 file.createNewFile();
 FileOutputStream fileStream = new FileOutputStream(file);
 BufferedOutputStream bufferStream = new BufferedOutputStream(fileStream);
 ZipOutputStream zipStream = new ZipOutputStream(bufferStream);
 zipStream.putNextEntry(new ZipEntry("bef"));
 ObjectOutputStream objectStream = new ObjectOutputStream(zipStream);
 objectStream.writeObject(extendedFormat);
 zipStream.closeEntry();
 objectStream.close();
 zipStream.close();
 bufferStream.close();
 fileStream.close();
} catch (FileNotFoundException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
} catch (IOException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
}

Is this the best way to do this? It seems a little over complicated but I want to save as much time writing it out and also space in terms of how big the file is that I write out.

I know this may seem like a lot for one object, but it can hold an entire table with possibly hundreds of columns and thousands of rows, so efficiency is important.

• Panayiotis Poularakis: Do you have any hard requirements to use Java < 8, or would you consider using a library for this?
• MMAdams: @PanayiotisPoularakis no, a library would be fine as long as it is one I can use in a commercial application.

Answer 1

You could use try-with-resources to efficiently close the streams, this also reduces line count and readability.

IOUtils provides a tested utility to copy between input and output streams, add commons-compress to you classpath, for example using gradle

 compile group: 'org.apache.commons', name: 'commons-compress',version: '1.14'

I simply extended the code you provided. I believe you will get the idea for reading back the zip file.

 try {
 File file = new File("C:/temp/tempExport.bef");
 file.createNewFile();
//Use try with resources to handle closing streams
 try (ZipOutputStream zipStream = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(file)))) {
 zipStream.putNextEntry(new ZipEntry("bef"));
 ObjectOutputStream objectStream = new ObjectOutputStream(zipStream);
 objectStream.writeObject(extendedFormat);
 }
 //to read the file you need a temp buffer or file to decompress the archive
 File temp = Files.createTempFile("", "").toFile();
 try (ZipInputStream zis = new ZipInputStream(new BufferedInputStream(new FileInputStream(file)));
 BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(temp));
 BufferedInputStream bis = new BufferedInputStream(new FileInputStream(temp))) {
 zis.getNextEntry();
 IOUtils.copy(zis, bos);
 bos.close();
 ObjectInputStream ois = new ObjectInputStream(bis);
 ExtendedFormat extendedFormat= (ExtendedFormat) ois.readObject();
 }
 temp.delete();
 } catch (FileNotFoundException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 } catch (IOException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 } catch (ClassNotFoundException e) {
 e.printStackTrace();
 }