解析原理
读取内容的情况下
DocumentBuilderFactory->DocumentBulder->Document->NodeList->Node->content
更改内容的情况下
TransformerFactory->Transformer->transform(Source, Result)
实例代码如下
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package com.gowhich.xmlparser;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.junit.Test;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class DomXmlParserTest {
@Test
public void domXmlParser() throws Exception {
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = builderFactory.newDocumentBuilder();
Document document = documentBuilder.parse("book.xml");
NodeList nodeList = document.getElementsByTagName("书名");
Node node = nodeList.item(1);
String content = node.getTextContent();
System.out.println(content);
}
@Test
public void domXmlModifyParser() throws Exception {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document document = documentBuilder.parse("book.xml");
NodeList nodeList = document.getElementsByTagName("书名");
for (int i = 0; i < nodeList.getLength(); i++) {
Node node = nodeList.item(i);
String content = node.getTextContent();
System.out.println(content);
}
Node node = nodeList.item(1);
node.setTextContent("书名2-改");
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
Source xmlSource = new DOMSource(document);
Result outputTarget = new StreamResult("book.xml");
transformer.transform(xmlSource , outputTarget);
}
}
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dom解析优缺点
优点:因为分配了一个树形结构,很容易的进行增加、删除、更改操作
缺点:如果要解析的文件过大,一次性在内存中分配一个树形结构,造成内存溢出