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Output Streaming multiple files into a zip file

Hie , I m generating report in csv format using solr , angularjs , Jax-rs and java. The input stream contain a csv response already because we have specified wt=csv while querying solr. Size of csv created from every input Stream might be 300mb .At java layer code is some thing like :
enter code here
InputStream is1;
InputStream is2;
// for is1 let file is csv1
// for is2 let file is csv2
// csvzip is the csv created form both two files
// now csvzip need to be downloaded through a popup
Creating big size file and zipfile in memory will not be a good approach surely.
Is there is any way to handle this?

Java - when there is no need of writing to file - should I use input or output stream?

I'm getting from the client an inputStream and file Metadata, and saving it in my SQL table. This table also holds full file path and some unique uid.
I want to be able to pass a uid and get a "handler" to the file, but can't seem to understand if I need to return outputStream, InputStream or File?
Which one should be returned?
I want this handler for the client for the following reasons:
The user will pass it to another function
The user will decide to convert stream to a file and copy it to some local path
Also, When returning outputstram,is it enough to do the following:
OutputStream out = new FileOutputStream(PATH_TO_MY_FILE))
return out;
Am I returning an empty stream? Does out contain all file data?
I thought maybe the best way will be to return file:
File f = new File(PATH_TO_MY_FILE);
return f;
Editing:
My metadata holds file name and file type. When I get InputStream I save in in my folder and set the path in the SQL table to be : folerPath+"/"+filename + "."+ fileType
When The user will run the following function : get(fileUid) I want to retrieve the full path (by using sql query) and return the file (hanlder)
Can you please advise?
Thanks

The user will decide to convert stream to a file and copy it to some local path
This tells us that what you need to give them is an InputStream (or Reader), since they'll be reading from it.
Your code will be reading from your database or whatever, presumably via the InputStream you get back from ResultSet#getBinaryStream or similar. You might give that directly to the caller, or you may prefer to have your code in the middle, perhaps working through a memory buffer.
Re your comment below:
I'm saving the file at some DB folder...
Databases don't have folders; file systems have folders. It sounds like the file isn't stored in your database table, just the path to it. If so, use FileInputStream with the path to get an InputStream for it, which you can return to the caller.

Thread.currentThread().getContextClassLoader().getResourceAsStream reads a property file multiple times

I have a property file named sysconfig.properties, I want to read it multiple times, because it is mutable.But I found when I changed the content of the sysconfig.properties then I read the content that is imutable, which is the same with the first time I read from the systemconfig.properties file.The content of the sysconfig.propertes file as follows:
isInitSuccess=TRUE
isStartValid=2013
May be sometime it will been changed as follows:
isInitSuccess=FALSE
isStartValid=2013
The code of read the properties file as follows:
InputStream inStream = Thread.currentThread().getContextClassLoader().getResourceAsStream(filePath);
I use the code read the file mutilple times, but every time the "isInitSuccess" is "TRUE", even though I changed the isInitSuccess=FALSE.Is the system just read it one time, then I read the file, it just get the input stream from the memory?
But when I use the code below, it will work fine:
InputStream inStream = new FileInputStream(new File(strPath));
I googled, but I did not find any help, the problem confused me a lot, any help would be appreciate.

You need to read up on what the classpath is.
In short, Java has a concept of classpath which includes all the resources (.class files, .properties files, and anything really) it needs to run. When you use ClassLoader#getResourceAsStream(String), you're actually getting the InputStream of a classpath resource. This resource can be a physical resource on disk or it can be in an archive.
When you use a FileInputStream, you are getting the InputStream of a file on disk.
The InputStream from the ClassLoader and the one from the FileInputStream do not correspond to the same file.
You should read up on how your IDE (or whatever build system) handles your files.

Creating a .txt file from scratch

I'm working on a microcontroller and I'm trying to write some data from some sensors into a .txt file on the SDcard and later on place the sd card in a card reader and read the data on the PC.
Does anyone know how to write a .txt file from scratch for a FAT32 file system? I don't have any predefined code/methods/functions to call, I'll need to create the code from nothin.
It's not a question for a specific programming language, that is why I tagged more than one. I can later on convert the code from C or Java to my programming language of choice. But I can't seem to find such low level methods/functions in any type of language :)
Any ideas?

FatFs is quite good, and highly portable. It has support for FAT12, FAT16 and FAT32, long filenames, seeking, reading and writing (most of these things can be switched on and off to change the memory footprint).
If you're really tight on memory there's also Petit FatFs, but it doesn't have write support by default and adding it would take some work.
After mounting the drive you'd simply open a file to create it. For example:
FATFS fatFs;
FIL newFile;
// The drive number may differ
if (f_mount(0, &fatFs) != FR_OK) {
// Something went wrong
}
if (f_open(&newFile, "/test.txt", FA_WRITE | FA_OPEN_ALWAYS) != FR_OK) {
// Something went wrong
}
If you really need to create the file using only your own code you'll have to traverse the FAT, looking for empty space and then creating new LFN entries (where you store the filename) and DIRENTs (which specify the clusters on the disk that will hold the file data).I can't see any reason for doing this except if this is some kind of homework / lab exercise. In any case you should do some reading about the FAT structure first and return with some more specific questions once you've got started.

In JAVA you can do like this
Writer output = null;
String text = "This is test message";
File file = new File("write.txt");
output = new BufferedWriter(new FileWriter(file));
output.write(text);
output.close();
System.out.println("Your file has been written");

How to use Android Internal Storage?

I am a beginner in java and I am building an android app.
I want to have an xml file that has text in it.
Whenever the server sends updates, I want to change some lines in that file (what I mean by update is changing some lines in that file by erasing the some part of the text written already and replace by the update)
I know nothing about creating,writing or reading from files.
When I searched I found out that Internal storage suits me best.
But I do not know if I have to create an xml file manually in any directory or just use the code bellow to create this file automatically?
// If this is the first time run,execute one time code
// create XML Internal store
String FILENAME = "My_XML_file";
try{
FileOutputStream fos = openFileOutput(FILENAME, Context.MODE_APPEND);
} catch (final IOException e) {
e.printStackTrace();
}
Thank you in advance!

- First give the External Storage permission in the Manifest.xml file.
- You can use JAXP & JAXB, and even CASTOR to handle XML in a better way, but still DOM and SAX are inbuilt into Android.
You can use something like this
String s = "/sdcard/Myfolder/mytext.txt";
File f = new File(s);

The code you have will create a file in internal storage but you need a bit more to create and maintain an XML file easily.
I suggest you use the Build in Android DOM Parser (Android developers site docs on XML Parse options)
I found this example which explains how to use the dom parser to build a specific (new) XML file from code. In your context where the output stream in created:
StreamResult result = new StreamResult(new File("C:\\file.xml"));
you might want to use the other constructor based on the output stream you created above
StreamResult result = new StreamResult(fos);
In a similar fashion this DOM library allows you to read from an input stream (which you might get from android openFileInput) using DocumentBuilder.parse()