在Java中压缩base 64 png图像

Question

Hi I would like to know if there is any way in Java to reduce the size of an image.Actually My front end is IOS,they are sending Base 64 encode data and when i'm getting the encoded data and i'm decoding the encoded data and storing in byte array. and now i want to compress the PNG image in java and my method code something like

public String  processFile(String strImageBase64, String strImageName,String donorId)
{       
    FileOutputStream fos =null;
    File savedFile=null;
    try
    {            
        String FileItemRefPath = propsFPCConfig.getProperty("fileCreationReferencePath");
        String imageURLReferncePath = propsFPCConfig.getProperty("imageURLReferncePath");
        File f = new File(FileItemRefPath+"\\"+"productimages"+"\\"+donorId);            
        String strException = "Actual File "+f.getName();            
        if(!f.exists())
        {
            boolean isdirCreationStatus = f.mkdir();                
        }            
        String strDateTobeAppended = new SimpleDateFormat("yyyyMMddhhmm").format(new Date(0));            
        String fileName = strImageName+strDateTobeAppended;            
        savedFile = new File(f.getAbsolutePath()+"\\"+fileName);            
        strException=strException+" savedFile "+savedFile.getName();            
        Base64 decoder = new Base64();            
        byte[] decodedBytes = decoder.decode(strImageBase64);                                    
        if( (decodedBytes != null) && (decodedBytes.length != 0) )
        {
            System.out.println("Decoded bytes length:"+decodedBytes.length);
            fos = new FileOutputStream(savedFile);                                
            System.out.println(new String(decodedBytes) + "\n") ;
            int x=0;
            {
                fos.write(decodedBytes, 0, decodedBytes.length);
            }
            fos.flush();
        }
        //System.out.println(savedFile.getCanonicalPath() +" savedFile.getCanonicalPath()  ");            
        if(fos != null)
        {
            fos.close();
            return savedFile.getAbsolutePath();
        }
        else
        {
            return null;
        }
    }
    catch(Exception e)
    {            
        e.printStackTrace();
    }
    finally
    {
        try
        {
            if( fos!= null)
            {
                fos.close();
            }
            else
            {
                savedFile = null;
            }
        }
        catch (IOException e)
        {                
            e.printStackTrace();
        }
    }        
    return savedFile.getName();
}

and i'm storing this decoded data with imagename,now i want to store this compressed image in anothe url

Answer 1

I don't think this should be worth the effort.

PNGs already have a very high level of compression. It is hard to reduce the size by means of additional compression significantly.

If you are really sending the image or the response Base64 encoded to the client, of course there are ways to improve transfer rates: Enable gzip compression on your server so that HTTP responses will be gzip compressed. This reduces the actual number of bytes to transfer quite a bit in case the original data is Base64 encoded (which basically means that you are only using 6 of 8 bits per bytes). Enabling gzip compression is transparent to your server code and is just a configuration switch away for most webservers.