为什么StAX创建XML比DOM慢？ [英] Why does StAX create XML slower than DOM?
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问题描述
我正在尝试测量StAX和DOM创建两个相同文档所需的时间。我不知道为什么DOM在创建XML时更快。也许我的StAX作家的代码不是很好。
所以这里是
StAX（更长的代码）
public static final int pocet = 100000;
try {
String encoding =UTF-8;
XMLOutputFactory f = XMLOutputFactory.newInstance（）;
XMLStreamWriter w = f.createXMLStreamWriter（
new FileOutputStream（subor），
encoding）;
w.writeStartDocument（encoding，1.0）;
w.writeCharacters（\r\\\
）;
w.writeStartElement（Noviny）; （int i = 1; i< = pocet; i ++）{
w.writeCharacters（\r\\\
）;
w.writeStartElement（Autor）;
w.writeCharacters（\r\\\
）;
w.writeStartElement（Id）;
String ID = Integer.toString（i）;
w.writeCharacters（ID）;
w.writeEndElement（）;
w.writeCharacters（\r\\\
）;
w.writeStartElement（Meno）;
w.writeCharacters（Autor+ i）;
w.writeEndElement（）;
w.writeCharacters（\r\\\
）;
w.writeStartElement（Email）;
w.writeCharacters（Autor+ i +@ email.com）;
w.writeEndElement（）;
w.writeCharacters（\r\\\
）;
w.writeStartElement（Tel_cislo）;
w.writeAttribute（typ，pevna）;
w.writeCharacters（+ 4219）;
w.writeEndElement（）;
w.writeCharacters（\r\\\
）;
w.writeStartElement（plat）;
w.writeCharacters（5000）;
w.writeEndElement（）;
w.writeCharacters（\r\\\
）;
w.writeEndElement（）;
w.writeCharacters（\r\\\
）;
}
w.writeCharacters（\r\\\
）;
w.writeEndElement（）;
w.writeCharacters（\r\\\
）;
w.writeEndDocument（）;
w.close（）;
}
catch（异常e）{
e.printStackTrace（）;
}
DOM
int pocet = 1500000;
try {
DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance（）;
DocumentBuilder builder = dfactory.newDocumentBuilder（）;
DOMImplementation domImpl = builder.getDOMImplementation（）;
文档文档= domImpl.createDocument（null，Noviny，null）;
Node noviny = document.getDocumentElement（）; （int i = 0; i< pocet; i ++）{
元素autor = document.createElement（autor）;
元素meno = document.createElement（meno）;
元素id = document.createElement（id）;
元素email = document.createElement（email）;
元素tel = document.createElement（tel_cislo）;
元素plat = document.createElement（plat）;
文本textid = document.createTextNode（+ i）;
文本textmeno = document.createTextNode（Autor+ i）;
文本textemail = document.createTextNode（mail@gmail.com）;
Text texttel = document.createTextNode（65456465465）;
文本textplat = document.createTextNode（200）;
noviny.appendChild（autor）;
autor.appendChild（id）;
id.appendChild（textid）;
autor.appendChild（meno）;
meno.appendChild（textmeno）;
autor.appendChild（email）;
email.appendChild（textemail）;
autor.appendChild（tel）;
tel.appendChild（texttel）;
autor.appendChild（plat）;
plat.appendChild（textplat）;
}
TransformerFactory factory = TransformerFactory.newInstance（）;
变压器变压器= factory.newTransformer（）;
transformer.setOutputProperty（OutputKeys.INDENT，yes）;
transformer.setOutputProperty（OutputKeys.ENCODING，UTF-8）;
transformer.transform（new DOMSource（document），new StreamResult（new File（subor）））;
我知道StAX在阅读文档时速度更快，但我不能解释这一点。除了我对StAX有不错的代码
谢谢
解决方案
在这里添加BufferedOuputStream
XMLStreamWriter w = f.createXMLStreamWriter（new BufferedOutputStream（new FileOutputStream（subor）），UTF-8） ;
现在测试速度，你会看到StAX至少快2倍。 b $ b
i was trying to measure time needed for StAX and DOM to create two same documents. I dont know why DOM is faster in creating XML. Maybe my code for StAX writer is not very good. so here it is StAX(longer code)
public static final int pocet =100000;
try {
String encoding = "UTF-8";
XMLOutputFactory f = XMLOutputFactory.newInstance();
XMLStreamWriter w = f.createXMLStreamWriter(
new FileOutputStream(subor),
encoding);
w.writeStartDocument(encoding, "1.0");
w.writeCharacters("\r\n");
w.writeStartElement("Noviny");
for (int i = 1; i <= pocet; i++) {
w.writeCharacters("\r\n ");
w.writeStartElement("Autor");
w.writeCharacters("\r\n ");
w.writeStartElement("Id");
String ID = Integer.toString(i);
w.writeCharacters(ID);
w.writeEndElement();
w.writeCharacters("\r\n ");
w.writeStartElement("Meno");
w.writeCharacters("Autor"+i);
w.writeEndElement();
w.writeCharacters("\r\n ");
w.writeStartElement("Email");
w.writeCharacters("Autor"+i+"@email.com");
w.writeEndElement();
w.writeCharacters("\r\n ");
w.writeStartElement("Tel_cislo");
w.writeAttribute("typ", "pevna");
w.writeCharacters("+4219");
w.writeEndElement();
w.writeCharacters("\r\n ");
w.writeStartElement("plat");
w.writeCharacters("5000");
w.writeEndElement();
w.writeCharacters("\r\n ");
w.writeEndElement();
w.writeCharacters("\r\n");
}
w.writeCharacters("\r\n");
w.writeEndElement();
w.writeCharacters("\r\n");
w.writeEndDocument();
w.close();
}
catch (Exception e) {
e.printStackTrace();
}
DOM
int pocet =1500000;
try {
DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = dfactory.newDocumentBuilder();
DOMImplementation domImpl = builder.getDOMImplementation();
Document document = domImpl.createDocument(null, "Noviny", null);
Node noviny = document.getDocumentElement();
for(int i = 0; i<pocet ; i++) {
Element autor = document.createElement("autor");
Element meno = document.createElement("meno");
Element id = document.createElement("id");
Element email = document.createElement("email");
Element tel = document.createElement("tel_cislo");
Element plat = document.createElement("plat");
Text textid = document.createTextNode(""+i);
Text textmeno = document.createTextNode("Autor"+i);
Text textemail = document.createTextNode("mail@gmail.com");
Text texttel = document.createTextNode("65456465465");
Text textplat = document.createTextNode("200");
noviny.appendChild(autor);
autor.appendChild(id);
id.appendChild(textid);
autor.appendChild(meno);
meno.appendChild(textmeno);
autor.appendChild(email);
email.appendChild(textemail);
autor.appendChild(tel);
tel.appendChild(texttel);
autor.appendChild(plat);
plat.appendChild(textplat);
}
TransformerFactory factory = TransformerFactory.newInstance();
Transformer transformer = factory.newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer.transform(new DOMSource(document),new StreamResult(new File(subor)));
i know that StAX is way faster in reading document, but i can´t explain this. Except that i have pretty bad code for StAX
thanks
解决方案
Add BufferedOuputStream here
XMLStreamWriter w = f.createXMLStreamWriter(new BufferedOutputStream(new FileOutputStream(subor)), "UTF-8");
now test the speed and you will see that StAX is at least 2 times faster
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