格式化xml

import java.io.StringWriter;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;

public class FormatXml{
    public static String formatXml(String xml){
        String res = null;
        try{
            Document doc = DocumentHelper.parseText(xml);
            OutputFormat format = OutputFormat.createPrettyPrint();
            StringWriter writer = new StringWriter();
            XMLWriter xmlWriter = new XMLWriter(writer,format);
            xmlWriter.write(doc);
            xmlWriter.close();
            res = writer.toString().trim();
        }catch(Exception e){}
        return res;
    }
}