问题描述
我正在接收一个 XML 文件作为输入，其大小可以从几 KB 到更多.我正在通过网络获取此文件.我需要根据我的使用提取少量节点，所以大部分文档对我来说毫无用处.我没有记忆偏好，我只需要速度.
I am receving an XML file as an input, whose size can vary from a few KBs to a lot more. I am getting this file over a network. I need to extract a small number of nodes as per my use, so most of the document is pretty useless for me. I have no memory preferences, I just need speed.
考虑到这一切，我得出结论:
Considering all this, I concluded :
这里不使用 DOM(由于 doc 可能很大，没有 CRUD 要求，并且来源是网络)
Not using DOM here (due to possible huge size of doc , no CRUD requirement, and source being network)
没有 SAX，因为我只需要获取一小部分数据.
No SAX as I only need to get a small subset of data.
StaX 可能是一种方法，但我不确定它是否是最快的方法.
StaX can be a way to go, but I am not sure if it is the fastest way.
JAXB 是另一种选择——但它使用什么样的解析器?我读到它默认使用 Xerces(这是什么类型 - 推或拉?)，尽管我可以按照这个 链接p>
JAXB came up as another option - but what sort of parser does it use ? I read it uses Xerces by default (which is what type - push or pull ?), although I can configure it for use with Stax or Woodstock as per this link
我读了很多书，仍然对这么多选项感到困惑！任何帮助将不胜感激.
I am reading a lot, still confused with so many options ! Any help would be appreciated.
谢谢！
我想在这里再添加一个问题:在这里使用 JAXB 有什么问题?
Edit : I want to add one more question here : What is wrong in using JAXB here ?
推荐答案
目前最快的解决方案是 StAX 解析器，特别是因为您只需要 XML 文件的特定子集，并且您可以轻松地忽略任何不需要使用的东西StAX，而如果您使用 SAX 解析器，无论如何您都会收到该事件.
Fastest solution is by far a StAX parser, specially as you only need a specific subset of the XML file and you can easily ignore whatever isn't really necessary using StAX, while you would receive the event anyway if you were using a SAX parser.
但它也比使用 SAX 或 DOM 稍微复杂一些.有一天，我不得不为以下 XML 编写 StAX 解析器:
But it's also a little bit more complicated than using SAX or DOM. One of these days I had to write a StAX parser for the following XML:
<?xml version="1.0"?>
<table>
<row>
<column>1</column>
<column>Nome</column>
<column>Sobrenome</column>
<column>email@gmail.com</column>
<column></column>
<column>2011-06-22 03:02:14.915</column>
<column>2011-06-22 03:02:25.953</column>
<column></column>
<column></column>
</row>
</table>
以下是最终解析器代码的样子:
Here's how the final parser code looks like:
public class Parser {
private String[] files ;
public Parser(String ... files) {
this.files = files;
}
private List<Inscrito> process() {
List<Inscrito> inscritos = new ArrayList<Inscrito>();
for ( String file : files ) {
XMLInputFactory factory = XMLInputFactory.newFactory();
try {
String content = StringEscapeUtils.unescapeXml( FileUtils.readFileToString( new File(file) ) );
XMLStreamReader parser = factory.createXMLStreamReader( new ByteArrayInputStream( content.getBytes() ) );
String currentTag = null;
int columnCount = 0;
Inscrito inscrito = null;
while ( parser.hasNext() ) {
int currentEvent = parser.next();
switch ( currentEvent ) {
case XMLStreamReader.START_ELEMENT:
currentTag = parser.getLocalName();
if ( "row".equals( currentTag ) ) {
columnCount = 0;
inscrito = new Inscrito();
}
break;
case XMLStreamReader.END_ELEMENT:
currentTag = parser.getLocalName();
if ( "row".equals( currentTag ) ) {
inscritos.add( inscrito );
}
if ( "column".equals( currentTag ) ) {
columnCount++;
}
break;
case XMLStreamReader.CHARACTERS:
if ( "column".equals( currentTag ) ) {
String text = parser.getText().trim().replaceAll( "
" , " ");
switch( columnCount ) {
case 0:
inscrito.setId( Integer.valueOf( text ) );
break;
case 1:
inscrito.setFirstName( WordUtils.capitalizeFully( text ) );
break;
case 2:
inscrito.setLastName( WordUtils.capitalizeFully( text ) );
break;
case 3:
inscrito.setEmail( text );
break;
}
}
break;
}
}
parser.close();
} catch (Exception e) {
throw new IllegalStateException(e);
}
}
Collections.sort(inscritos);
return inscritos;
}
public Map<String,List<Inscrito>> parse() {
List<Inscrito> inscritos = this.process();
Map<String,List<Inscrito>> resultado = new LinkedHashMap<String, List<Inscrito>>();
for ( Inscrito i : inscritos ) {
List<Inscrito> lista = resultado.get( i.getInicial() );
if ( lista == null ) {
lista = new ArrayList<Inscrito>();
resultado.put( i.getInicial(), lista );
}
lista.add( i );
}
return resultado;
}
}
代码本身是葡萄牙语，但你应该很容易理解它是什么，这里是github上的repo.
The code itself is in portuguese but it should be straightforward for you to understand what it is, here's the repo on github.
这篇关于在这里使用哪个 XML 解析器?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持跟版网！