Copying an XML document into a String Variable in Java

Question

I am trying to copy an entire XML document, tagnames/tagtypes irrelavant, into a String varible. Language to be used is Java. I used ReadAllText to do it in C#, but I need to find an equivalent of that command in Java or another idea to be able to have the entire XML document as a String. I have been working on this for a while now. This is part of a bigger project. This is the only thing that is left to be done. Any suggestions? Thanks in Advance.

Answer 1

Well since this is java and not a scripting language, you will just need to use a scanner or file reader and read it line by line and append it into a single string.

This website has a great overview of file io in java. I actually learned a lot even after knowing about file io.

Here is a sample of what you could do:

private void processFile(File file)
{
        StringBuilder allText = new StringBuilder();
        String line;
        Scanner reader = null;
        try {
            FileInputStream fis = new FileInputStream(propertyFile);
            InputStreamReader in = new InputStreamReader(fis, "ISO-8859-1");
            reader = new Scanner(in);
            while(reader.hasNextLine() && !errorState)
            {
                line = reader.nextLine();
                allText.append(line);
            }
        } catch (FileNotFoundException e)
        {
            System.err.println("Unable to read file");
            errorState=true;
        } catch (UnsupportedEncodingException e) {
            System.err.println("Encoding not supported");
            errorState=true;
        }
        finally
        {
            reader.close();
        }
}

Answer 2

Try following code:

public String convertXMLFileToString(String fileName) 
{ 
    try { 
        DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance(); 
        InputStream inputStream = new FileInputStream(new File(fileName)); 
        org.w3c.dom.Document doc = documentBuilderFactory.newDocumentBuilder().parse(inputStream); 
        StringWriter stw = new StringWriter(); 
        Transformer serializer = TransformerFactory.newInstance().newTransformer(); 
        serializer.transform(new DOMSource(doc), new StreamResult(stw)); 
        return stw.toString(); 
    } catch (Exception e) { 
        e.printStackTrace(); 
    } 
    return null; 
}

Answer 3

use an StringWriter with a StreamResult.

note, be very careful what you do with that string after that. if you later write it to a stream/byte[] of some sort using the wrong character encoding, you will generate broken xml data.

Answer 4

I used a buffered Reader the last time I did this. Worked well.

String output = "";
try {
  FileInputStream is = new FileInputStream(file);
  BufferedReader br = new BufferedReader(new InputStreamReader(is));
  String line = "";
  while ((line = br.readLine()) != null) {
    output = output + line;
  }
  br.close();
  is.close();
} catch(IOException ex) {
  //LOG!
}

My original implementation was to use an actual buffer but I seemed to keep having issues with flushing the buffer so I went this way which is super easy.

Answer 5

Many answers that get it almost, but not quite, correct.

• If you use a BufferedInputStream and read lines, the result is missing line breaks
• If you use a BufferedReader or a Scanner and read lines, the result is missing the original line breaks an the encoding may be wrong.
• If you use a Writer in a Result, the encoding may not match the source

If you positively know the source encoding, you can do this:

String file2string(File f, Charset cs) throws IOException {
    ByteArrayOutputStream out = new ByteArrayOutputStream(10000);
    InputStream in = new BufferedInputStream(new FileInputStream(f));
    int c;
    while ((c = in.read()) != -1)
        out.write(c);
    in.close();
    return out.toString(cs.name());
}

If you don't know the source encoding, rely on the XML parser to detect it and control the output:

String transform2String(File f, Charset cs) throws IOException,
        TransformerFactoryConfigurationError, TransformerException {
    Transformer t = TransformerFactory.newInstance().newTransformer();
    t.setOutputProperty(OutputKeys.ENCODING, cs.name());
    ByteArrayOutputStream out = new ByteArrayOutputStream(10000);
    t.transform(new StreamSource(new BufferedInputStream(
            new FileInputStream(f))), new StreamResult(out));
    return out.toString(cs.name());
}