java StAX – StartDocument的独立属性

我想阅读，操作和编写一个xml文件。 我想先从读写开始，然后再操作。

我使用StAX Parser并希望使用EventReader和EventWriter。

我想在读取和编写StartDocument元素时遇到了第一个问题。

输入：

文件“data_output_test.xml”中的输出：

我用显式创建了startDocument对象

 eventFactory.createStartDocument("iso-8859-15", "1.0", true); 

但是当我将新的startDocument对象写入文件时，该属性不会显示。

这是我的代码：

 import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import javax.xml.stream.XMLEventFactory; import javax.xml.stream.XMLEventReader; import javax.xml.stream.XMLEventWriter; import javax.xml.stream.XMLInputFactory; import javax.xml.stream.XMLOutputFactory; import javax.xml.stream.XMLStreamConstants; import javax.xml.stream.XMLStreamException; import javax.xml.stream.events.XMLEvent; public class XML_ReadWrite{ @SuppressWarnings("unchecked") public static void main(String[] args) { XMLInputFactory factory_in = null; XMLOutputFactory factory_out = null; XMLEventReader eventReader = null; XMLEventFactory eventFactory = null; XMLEventWriter eventWriter = null; XMLEvent event_out = null; XMLEvent event_in = null; try { factory_in = XMLInputFactory.newInstance(); eventReader = factory_in.createXMLEventReader (getReader("data_test.xml", "iso-8859-15")); } catch (XMLStreamException e) { e.printStackTrace(); return; } catch (Exception e) { //UnsupportedEncodingException or FileNotFoundException e.printStackTrace(); return; } try { factory_out = XMLOutputFactory.newInstance(); eventFactory = XMLEventFactory.newInstance(); eventWriter = factory_out.createXMLEventWriter(getWriter("data_output_test.xml", "iso-8859-15")); event_out = eventFactory.createStartDocument(null, "1.0", true); eventWriter.add(event_out); eventWriter.flush(); } catch (XMLStreamException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (Exception e) { //UnsupportedEncodingException or FileNotFoundException e.printStackTrace(); return; } while(eventReader.hasNext()){ try { event_in = eventReader.nextEvent(); } catch (XMLStreamException e) { e.printStackTrace(); continue; } if(event_in.getEventType() == XMLStreamConstants.START_DOCUMENT){ System.out.println("StartElement: " + event_in.isStartDocument()); System.out.println("StartElement: " + event_in.toString()); } } } public static InputStreamReader getReader(String filename, String encoding) throws Exception { FileInputStream in = new FileInputStream(filename); InputStreamReader r = null; r = new InputStreamReader(in, encoding); return r; } public static OutputStreamWriter getWriter(String filename, String encoding) throws Exception { FileOutputStream out = new FileOutputStream(filename); OutputStreamWriter w = new OutputStreamWriter(out, encoding); return w; } } 

有没有办法强制XMLEventWriter编写独立属性呢？

我的第二个问题是，当我这样做时，无法识别编码

 event_in.toString() 

在事件startDocument上。

我的程序输出是：

 StartElement: true StartElement:  

这是为什么？

提前谢谢了