How to decompress a GZip string on the server side script include

[vkachineni]

Community,

I have a situation where I need to unzip the contents of a Gzip string from attachment_doc table

var strEncodedString1 = 'H4sIAAAAAAAAAA==';
var strEncodedString2 = 'c3RydgEApSAX2wQAAAA=';

//Got the above stings from a REST call to the sys_attachment_doc table. It is a text file with ABCD as content.

var objStringUtil = new GlideStringUtil();
var bytes1 = objStringUtil.base64Decode(strEncodedString1);
var bytes2 = objStringUtil.base64Decode(strEncodedString2);

//This gives a zip string. I would have to decompress it to get the contents as text ABCD
gs.log(bytes1 + bytes2);

I am stuck at the decompressing part.

Looking for suggestions on how to proceed.

Do I need to write a Java class to call the GZIPInputStream to return a decompressed string?

Suggestions please.

Thanks,

vkachineni

[anjiadmin]

Hi Vkachineni,

Did you find a solution for this as I have a same type of requirement .

Please let me know if you find anything .

Thanks,

Anji

[vkachineni]

Sorry. Could not find a native solution. Alternative is to write a Java or .NET program to get data and decompress it and write it to memory/disk. Here is an example java class.

//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111
import java.io.*; 
import java.util.*;
import java.lang.*;
import java.util.Base64.*;
import java.util.Collections;
import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
import java.nio.*;
import java.nio.charset.StandardCharsets;
class Rextester
{  
    public static void main(String args[])
    {
        Stack<Integer> fullResponse = new Stack<Integer>();
        byte[] bytes1 = Base64.getDecoder().decode("H4sIAAAAAAAAAA==");
		byte[] bytes2 = Base64.getDecoder().decode("c3RydgEApSAX2wQAAAA=");

        for(int i=0; i<=bytes1.length -1; i++)
        {
            
            int n = (bytes1[i] + 256) % 256;
            fullResponse.push(n);
            //System.out.println(n);
            
        }
        //System.out.println("************");
        for(int i=0; i<=bytes2.length -1; i++)
        {
            int n = (bytes2[i] + 256) % 256;
            fullResponse.push(n);
           // System.out.println(n);
            
        }
        //System.out.println("Full =" + fullResponse);
        /*Stack<Integer> fullResponseCorrectOrder = new Stack<Integer>();
        while(!fullResponse.isEmpty())
        {
            fullResponseCorrectOrder.push(fullResponse.pop());
            
        }
        //System.out.println("Full =" + fullResponseCorrectOrder);*/
        // Creating the array and using toArray() 
        Integer[] arr = new Integer[fullResponse.size()]; 
        arr = fullResponse.toArray(arr); 
        for(int i = 0; i < arr.length; i++){            
            //System.out.println(arr[i]);
        }
        decompress(arr);
		
        
        
    }
	public static void decompress(Integer[] data)
	{
        try{
            byte[] bytes = convertIntArrayToByteArray(data);
            ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
            GZIPInputStream gis = new GZIPInputStream(bis);
            
            byte[] buffer = new byte[1024];
            int len;
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            while((len = gis.read(buffer)) != -1){
                bos.write(buffer, 0, len);
            }
            byte[] result = bos.toByteArray();
            //close resources
            bis.close();
            gis.close();
            String string = new String(result, StandardCharsets.UTF_8);
            System.out.println(string);
            
            
        }catch (IOException e) {
            e.printStackTrace();
        }
        
	}
    public static int[] toPrimitives(Integer[] oInts)
    {

        int[] ints = new int[oInts.length];
        for(int i = 0; i < oInts.length; i++){
            ints[i] = oInts[i];
            //System.out.println(bytes[i]);
        }
        return ints;

    }
    public static byte[] convertIntArrayToByteArray(Integer[] data) {
        if (data == null) return null;
        // ----------
        byte[] byts = new byte[data.length * 4];
        for (int i = 0; i < data.length; i++)
            byts[i] = data[i].byteValue();
            
            //System.arraycopy(convertIntToByteArray(data[i]), 0, byts, i * 4, 4);
        return byts;
    }
    
}

[anjiadmin]

How can we use the Java code in Servicenow?

Thanks,

Anji