dom4j不想出现空行

OutputFormat format = new OutputFormat();  
format.setEncoding("UTF-8");  
format.setIndent(true);    // 设置是否缩进 
format.setIndent("   ");   // 以空格方式实现缩进 
format.setNewlines(true);  
format.setTrimText(true);
[b][size=large][color=blue]format.setExpandEmptyElements(true);[/color][/size][/b]
FileOutputStream fos=new FileOutputStream(file);
XMLWriter output =new XMLWriter(fos,format);
output.write(doc);
output.close();