XML之StAX（二）

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XML之StAX（一）

XML之StAX（二）

面向Stream的StAX

XMLStreamReader

StAX中的XMLStreamReader类提供了一个Cursor形式的API，用于解析XML。和Iterator API一样，允许你确定何时访问下一个Event，这里的Event是元素开头，元素的结尾，一组text等。XMLStreamReader的next()方法不返回Events，而是移动Cursor到下一个XML的Event。你可以直接调用方法获取当前Event的更多信息，这和你迭代JDBC ResultSet的记录一样。下面是你可能遇到的XML Stream的Events，它们包含在javax.xml.stream.XMLStreamConstants：

ATTRIBUTE
CDATA
CHARACTERS
COMMENT
DTD
END_DOCUMENT
END_ELEMENT
ENTITY_DECLARATION
ENTITY_REFERENCE
NAMESPACE
NOTATION_DECLARATION
PROCESSING_INSTRUCTION
SPACE
START_DOCUMENT
START_ELEMENT

下面是一个简单的例子：

public static void read()throws IOException{XMLInputFactory factory = XMLInputFactory.newFactory();Reader reader = null;try {//            reader = new FileReader("F:\\Codes\\IDEA\\Tools\\data\\xml\\test.xml");InputStream input = CursorAccess.class.getClassLoader().getResourceAsStream("test.xml");XMLStreamReader streamReader = factory.createXMLStreamReader(input);while (streamReader.hasNext()){int type = streamReader.next();  // streamReader.getEventType() == XMLStreamReader.START_ELEMENT == XMLStreamConstans.START_ELEMENT  // equals streamReader.isStartElement() and type==XMLStreamConstans.START_ELEMENTif(streamReader.isStartElement()){QName element = streamReader.getName();String name = element.toString();//if(name.equals("book")) {QName attrName = streamReader.getAttributeName(0);String attrValue = streamReader.getAttributeValue(0);System.out.println(element + ": " + attrName + "=" + attrValue);}else if(!name.equals("bookstore") && !name.equals("book")){String value = streamReader.getElementText();System.out.println(element + ": " + value);}}}}catch (Exception e){e.printStackTrace();}finally {if(reader != null) {reader.close();}}}

和XMLEventReader一样，XMLStreamReader也可以自定义Filter：

public static void readFilter()throws IOException{XMLInputFactory factory = XMLInputFactory.newFactory();InputStream input = null;try {input = new FileInputStream(new File("F:\\Codes\\IDEA\\Tools\\data\\xml\\test.xml"));XMLStreamReader streamReader = factory.createFilteredReader(factory.createXMLStreamReader(input), new StreamFilter() {@Overridepublic boolean accept(XMLStreamReader reader) {if(reader.isStartElement()){String name = reader.getName().toString();if(name.equals("title") || name.equals("price")){return true;}}return false;}});while (streamReader.hasNext()){streamReader.next();if(streamReader.isStartElement()){String name = streamReader.getLocalName();System.out.println(name + ": " + streamReader.getElementText());}}}catch (Exception e){e.printStackTrace();}finally {if(input != null){input.close();}}}

XMLStreamWriter

XMLStreamWriter是用于生成XML的，不过不同于XMLEventWriter的是，它不要求为元素定义前缀：

public static void write(){XMLOutputFactory factory = XMLOutputFactory.newFactory();try {XMLStreamWriter writer = factory.createXMLStreamWriter(new FileWriter("F:\\Codes\\IDEA\\Tools\\data\\xml\\cursor.xml"));writer.writeStartDocument();writer.writeStartElement("test:bookstore");writer.writeStartElement("test:book");writer.writeAttribute("category", "COMPUTER");writer.writeStartElement("author");writer.writeCharacters("Giada De Laurentiis");writer.writeEndElement();writer.writeEndElement();writer.writeEndElement();writer.writeEndDocument();writer.flush();writer.close();}catch (Exception e){e.printStackTrace();}}

完整代码托管在：https://github.com/GatsbyNewton/xml-stax

参考文献：

http://www.w3school.com.cn/xml/index.asp

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