读取xml的最快和最优化的方法 [英] Fastest and optimized way to read the xml
问题描述
我有以下XML文件
<book>
<person>
<first>Kiran</first>
<last>Pai</last>
<age>22</age>
</person>
<person>
<first>Bill</first>
<last>Gates</last>
<age>46</age>
</person>
<person>
<first>Steve</first>
<last>Jobs</last>
<age>40</age>
</person>
</book>
现在从XML文件读取数据的Java程序如下所示..
now the Java program to read data from an XML file is shown below..
import java.io.File;
import org.w3c.dom.Document;
import org.w3c.dom.*;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
public class ReadAndPrintXMLFile{
public static void main (String argv []){
try {
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
Document doc = docBuilder.parse (new File("book.xml"));
// normalize text representation
doc.getDocumentElement ().normalize ();
System.out.println ("Root element of the doc is " +
doc.getDocumentElement().getNodeName());
NodeList listOfPersons = doc.getElementsByTagName("person");
int totalPersons = listOfPersons.getLength();
System.out.println("Total no of people : " + totalPersons);
for(int s=0; s<listOfPersons.getLength() ; s++){
Node firstPersonNode = listOfPersons.item(s);
if(firstPersonNode.getNodeType() == Node.ELEMENT_NODE){
Element firstPersonElement = (Element)firstPersonNode;
//-------
NodeList firstNameList = firstPersonElement.getElementsByTagName("first");
Element firstNameElement = (Element)firstNameList.item(0);
NodeList textFNList = firstNameElement.getChildNodes();
System.out.println("First Name : " +
((Node)textFNList.item(0)).getNodeValue().trim());
//-------
NodeList lastNameList = firstPersonElement.getElementsByTagName("last");
Element lastNameElement = (Element)lastNameList.item(0);
NodeList textLNList = lastNameElement.getChildNodes();
System.out.println("Last Name : " +
((Node)textLNList.item(0)).getNodeValue().trim());
//----
NodeList ageList = firstPersonElement.getElementsByTagName("age");
Element ageElement = (Element)ageList.item(0);
NodeList textAgeList = ageElement.getChildNodes();
System.out.println("Age : " +
((Node)textAgeList.item(0)).getNodeValue().trim());
//------
}//end of if clause
}//end of for loop with s var
}catch (SAXParseException err) {
System.out.println ("** Parsing error" + ", line "
+ err.getLineNumber () + ", uri " + err.getSystemId ());
System.out.println(" " + err.getMessage ());
}catch (SAXException e) {
Exception x = e.getException ();
((x == null) ? e : x).printStackTrace ();
}catch (Throwable t) {
t.printStackTrace ();
}
//System.exit (0);
}//end of main
}
,结果是..
Root element of the doc is book
Total no of people : 3
First Name : Kiran
Last Name : Pai
Age : 22
First Name : Bill
Last Name : Gates
Age : 46
First Name : Steve
Last Name : Jobs
Age : 40
现在我的查询是请建议有没有其他方法,这是最快的阅读这个xml,我正在寻找紧张,请建议.. !!
Now my query is please advise is there any other way which is fastest to read this xml , I was looking the fastes , Please advise..!!
推荐答案
使用 ReadAndPrintXMLFileWithStAX
,当我从 ReadAndPrintXMLFileWithSAX 进行比较时://stackoverflow.com/a/12271247/383861> gontard给出的答案 StAX方法更快。我的测试包括在JDK 1.7.0_07上为Mac运行示例代码 500000
次。
Using ReadAndPrintXMLFileWithStAX
below, when I compare with ReadAndPrintXMLFileWithSAX
from the answer given by gontard the StAX approach is faster. My test involved running both sample code 500000
times on JDK 1.7.0_07 for the Mac.
ReadAndPrintXMLFileWithStAX: 103 seconds
ReadAndPrintXMLFileWithSAX: 125 seconds
ReadAndPrintXMLFileWithStAX(使用Java SE 7)
下面是一个更优化的StAX(JSR-173)示例,使用 XMLStreamReader
而不是 XMLEventReader
。
Below is a more optimized StAX (JSR-173) example using XMLStreamReader
instead of XMLEventReader
.
import java.io.FileInputStream;
import java.io.InputStream;
import javax.xml.stream.*;
public class ReadAndPrintXMLFileWithStAX {
public static void main(String argv[]) throws Exception {
XMLInputFactory inputFactory = XMLInputFactory.newInstance();
InputStream in = new FileInputStream("book.xml");
XMLStreamReader streamReader = inputFactory.createXMLStreamReader(in);
streamReader.nextTag(); // Advance to "book" element
streamReader.nextTag(); // Advance to "person" element
int persons = 0;
while (streamReader.hasNext()) {
if (streamReader.isStartElement()) {
switch (streamReader.getLocalName()) {
case "first": {
System.out.print("First Name : ");
System.out.println(streamReader.getElementText());
break;
}
case "last": {
System.out.print("Last Name : ");
System.out.println(streamReader.getElementText());
break;
}
case "age": {
System.out.print("Age : ");
System.out.println(streamReader.getElementText());
break;
}
case "person" : {
persons ++;
}
}
}
streamReader.next();
}
System.out.print(persons);
System.out.println(" persons");
}
}
输出
First Name : Kiran
Last Name : Pai
Age : 22
First Name : Bill
Last Name : Gates
Age : 46
First Name : Steve
Last Name : Jobs
Age : 40
3 persons
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