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如何使用Java 1.4和SAX将任意数据编码为XML？

2023-04-16 00:02:00

How do I encode arbitrary data to XML using Java 1.4 and SAX?

我们使用SAX来解析XML，因为它不需要为了解析单个值而将整个XML文档读入内存。我读过许多文章，坚持认为SAX只能用于解析/解码XML，而不能创建XML。这是真的？

不，这不是真的，您可以使用类似于以下内容的方式将XML编码为Java中的任何Writer：

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char[] ch;
AttributesImpl atts = new AttributesImpl();
Writer writer = new StringWriter();
StreamResult streamResult = new StreamResult(writer);
SAXTransformerFactory tf = (SAXTransformerFactory) TransformerFactory.newInstance();

// SAX2.0 ContentHandler
TransformerHandler transformerHandler = tf.newTransformerHandler();

Transformer serializer = transformerHandler.getTransformer();

serializer.setOutputProperty(OutputKeys.ENCODING,"UTF-8");
// serializer.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM,"nodes.dtd");
serializer.setOutputProperty(OutputKeys.INDENT,"yes");

transformerHandler.setResult(streamResult);

transformerHandler.startDocument();

atts.clear();
// atts.addAttribute("","","xmlns","CDATA","http://www.example.com/nodes");
// atts.addAttribute("","","xmlns:xsi","CDATA","http://www.w3.org/2001/XMLSchema-instance");
// atts.addAttribute("","","xsi:schemaLocation","CDATA","/nodes.xsd");
transformerHandler.startElement("","","node_list", atts);

// displayName element
if (displayName != null) {
transformerHandler.startElement("","","display_name", null);
ch = displayName.toCharArray();
transformerHandler.characters(ch, 0, ch.length);
transformerHandler.endElement("","","display_name");
}

// nodes element
transformerHandler.startElement("","","nodes", null);

atts.clear();
atts.addAttribute("","","node_type","CDATA","sometype");
transformerHandler.startElement("","","node", atts);

ch = node.getValue().toCharArray();
transformerHandler.startElement("","","value", null);
transformerHandler.characters(ch, 0, ch.length);
transformerHandler.endElement("","","value");

transformerHandler.endElement("","","node");

transformerHandler.endElement("","","nodes");

transformerHandler.endElement("","","node_list");

transformerHandler.endDocument();

String xml = writer.toString();

SAX处理程序接口的设计易于实现。编写具有类似内容的类很容易(也许包装了SAX接口)以使其易于调用-链接，记住要关闭的元素，更容易的属性等。

数据编码内存文档用于