Java解析XML的四種方法

時間 2019-11-12

標籤 java 解析 xml 四種方法欄目 Java 简体版

原文原文鏈接

XML文件解析方法 java

XML在不一樣的語言裏解析方式都是同樣的,只不過實現的語法不一樣而已。基本的解析方式有兩種,一種叫SAX，另外一種叫DOM。SAX是基於事件流的解析,DOM是基於XML文檔樹結構的解析。假設咱們XML的內容和結構以下: node

<?xml version="1.0" encoding="UTF-8"?>

<employees>
<employee>
<name>ddviplinux</name>
<sex>m</sex>
<age>30</age>
</employee>
</employees>

本文實現DOM與SAX的XML文檔生成與解析。

首先定義一個操做XML文檔的接口XmlDocument 它定義了XML文檔的創建與解析的接口。 linux

package com.alisoft.facepay.framework.bean;
/**
*
* @author hongliang.dinghl
* 定義XML文檔創建與解析的接口
*/
public interface XmlDocument {
/**
* 創建XML文檔
* @param fileName 文件全路徑名稱
*/
public void createXml(String fileName);
/**
* 解析XML文檔
* @param fileName 文件全路徑名稱
*/
public void parserXml(String fileName);
}

1.DOM生成和解析XML文檔 程序員

爲 XML 文檔的已解析版本定義了一組接口。解析器讀入整個文檔，而後構建一個駐留內存的樹結構，而後代碼就可使用 DOM 接口來操做這個樹結構。優勢：整個文檔樹在內存中，便於操做；支持刪除、修改、從新排列等多種功能；缺點：將整個文檔調入內存（包括無用的節點），浪費時間和空間；使用場合：一旦解析了文檔還需屢次訪問這些數據；硬件資源充足（內存、CPU）。編程

（1）DOM解析XML文檔所使用到的jar：dom.jar app

（2）DOM解析與建立XML文檔示例代碼 dom

package com.alisoft.facepay.framework.bean;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
/**
*
* @author hongliang.dinghl DOM生成與解析XML文檔
*/
public class DomDemo implements XmlDocument {
private Document document;
private String fileName;
public void init() {
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
this.document = builder.newDocument();
} catch(ParserConfigurationException e) {
System.out.println(e.getMessage());
}
}
//建立一個xml文件
public void createXml(String fileName) {
Element root = this.document.createElement("employees"); //建立一個xml文件根節點
this.document.appendChild(root); //把根節點加到xml文檔結構下面
Element employee = this.document.createElement("employee"); //創過employee節點
Element name = this.document.createElement("name"); //建立name節點
name.appendChild(this.document.createTextNode("丁宏亮")); //建立一個內容,並把內容加到name節點下面
employee.appendChild(name); //把name加到employee下面
Element sex = this.document.createElement("sex"); //建立軍一個sex節點
sex.appendChild(this.document.createTextNode("m")); //建立一個性別添加到性別節點下面
employee.appendChild(sex); //把性別添加到,人員節點下面
Element age = this.document.createElement("age");
age.appendChild(this.document.createTextNode("30"));
employee.appendChild(age);
root.appendChild(employee);
TransformerFactory tf = TransformerFactory.newInstance();
try {
Transformer transformer = tf.newTransformer();
DOMSource source = new DOMSource(document);
transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312");
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
PrintWriter pw = new PrintWriter(new FileOutputStream(fileName));
StreamResult result = new StreamResult(pw);
transformer.transform(source, result);
System.out.println("生成XML文件成功!");
} catch (TransformerConfigurationException e) {
System.out.println(e.getMessage());
} catch (IllegalArgumentException e) {
System.out.println(e.getMessage());
} catch (FileNotFoundException e) {
System.out.println(e.getMessage());
} catch (TransformerException e) {
System.out.println(e.getMessage());
}
}
//解釋一個XML文件
public void parserXml(String fileName) {
try {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document document = db.parse(fileName); // 讀取xml文件
NodeList employees = document.getChildNodes();
for (int i = 0; i < employees.getLength(); i++) {
Node employee = employees.item(i);
NodeList employeeInfo = employee.getChildNodes();
for (int j = 0; j < employeeInfo.getLength(); j++) {
Node node = employeeInfo.item(j);
NodeList employeeMeta = node.getChildNodes();
for (int k = 0; k < employeeMeta.getLength(); k++) {
System.out.println(employeeMeta.item(k).getNodeName()
+ ":" + employeeMeta.item(k).getTextContent());
}
}
}
System.out.println("解析完畢");
} catch (FileNotFoundException e) {
System.out.println(e.getMessage());
} catch (ParserConfigurationException e) {
System.out.println(e.getMessage());
} catch (SAXException e) {
System.out.println(e.getMessage());
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
}

2.SAX生成和解析XML文檔

爲解決DOM的問題，出現了SAX。SAX ，事件驅動。當解析器發現元素開始、元素結束、文本、文檔的開始或結束等時，發送事件，程序員編寫響應這些事件的代碼，保存數據。優勢：不用事先調入整個文檔，佔用資源少；SAX解析器代碼比DOM解析器代碼小，適於Applet，下載。缺點：不是持久的；事件事後，若沒保存數據，那麼數據就丟了；無狀態性；從事件中只能獲得文本，但不知該文本屬於哪一個元素；使用場合：Applet;只需XML文檔的少許內容，不多回頭訪問；機器內存少；編程語言

（1）SAX解析XML文檔所使用到的jar包：sax.jar ide

（2）SAX關健類的，類結構圖性能

（3）SAX文檔解釋示例代碼

package com.alisoft.facepay.framework.bean;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;
public class XMLParser {
protected PrintStream output = new PrintStream(new BufferedOutputStream(
new FileOutputStream(java.io.FileDescriptor.out), 128), true);
// handler error info.
protected PrintStream error = new PrintStream(new BufferedOutputStream(
new FileOutputStream(java.io.FileDescriptor.err), 128), true);
public void parserXMLFile(String fileName) throws SAXException, IOException {
XMLReader reader = XMLReaderFactory.createXMLReader();
reader.setContentHandler(new MyContentHandler());
reader.setErrorHandler(new MyErrorHandler());
InputSource source = new InputSource(new FileInputStream(new File(
fileName)));
reader.parse(source);
}
class MyErrorHandler implements ErrorHandler {
public void error(SAXParseException exception) throws SAXException {
error.println(exception.getMessage());
}
public void fatalError(SAXParseException exception) throws SAXException {
error.println(exception.getMessage());
}
public void warning(SAXParseException exception) throws SAXException {
output.println(exception.getMessage());
}
}
class MyContentHandler implements ContentHandler {
private StringBuffer buffer = new StringBuffer();
private String key;
public void characters(char[] ch, int start, int length)
throws SAXException {
buffer.append(ch, start, length); // 添加標記中間的內容
}
public void endDocument() throws SAXException {
}
public void endElement(String uri, String localName, String name)
throws SAXException {
if (key.equals(localName)) {
output.print(buffer); // 輸出標記中間的內容
}
output.print("</" + localName + ">");
}
public void endPrefixMapping(String prefix) throws SAXException {
}
public void ignorableWhitespace(char[] ch, int start, int length)
throws SAXException {
}
public void processingInstruction(String target, String data)
throws SAXException {
}
public void setDocumentLocator(Locator locator) {
}
public void skippedEntity(String name) throws SAXException {
}
public void startDocument() throws SAXException // XML文檔開始讀取時調用
{
output.println("<xml version=\"1.0\" encoding=\"utf-8\"?>");
}
public void startElement(String uri, String localName, String name,
Attributes atts) throws SAXException // 獲取標記開始信息
{
// uri is identifier of namespace
// name-->prefix:localName
buffer.delete(0, buffer.length());
key = localName;
output.print("<" + localName);
for (int i = 0; i < atts.getLength(); i++) {
String attrName = atts.getLocalName(i);
String attrValue = atts.getValue(i);
output.print(" " + attrName + "=" + attrValue);
}
output.print(">" + "\r");
}
public void startPrefixMapping(String prefix, String uri)
throws SAXException {
}
}
public static void main(String[] args) throws Exception, IOException {
XMLParser parser = new XMLParser();
parser.parserXMLFile("D:/testSpace/testPrj/src/xmlPackage/MyXml.xml"); // 解釋XML文件
}
}

（4）SAX生成XML文檔示例代碼(生成XML)

package com.alisoft.facepay.framework.bean;

import java.io.FileOutputStream;
import java.io.StringWriter;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Result;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;
public class XMLHandler {
public String createXMLFile() {
String xmlStr = null;
try {
Result resultXml = new StreamResult(new FileOutputStream(
"E://cities.xml"));
StringWriter writerStr = new StringWriter();
SAXTransformerFactory sff = (SAXTransformerFactory) SAXTransformerFactory
.newInstance();
TransformerHandler th = sff.newTransformerHandler();
Transformer transformer = th.getTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
th.setResult(resultXml);
th.startDocument();
String four = "\n ";
String eight = "\n ";
AttributesImpl attr = new AttributesImpl();
th.startElement("", "", "country", attr);
th.characters(four.toCharArray(), 0, four.length());
th.startElement("", "", "china", attr);
th.characters(eight.toCharArray(), 0, eight.length());
th.startElement("", "", "city", attr);
String bj = "Beijing";
th.characters(bj.toCharArray(), 0, bj.length());
th.endElement("", "", "city");
th.characters(eight.toCharArray(), 0, eight.length());
th.startElement("", "", "city", attr);
String sh = "Shanghai";
th.characters(sh.toCharArray(), 0, sh.length());
th.endElement("", "", "city");
th.characters(four.toCharArray(), 0, four.length());
th.endElement("", "", "china");
th.endElement("", "", "country");
th.endDocument();
xmlStr = writerStr.getBuffer().toString();
} catch (TransformerConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return xmlStr;
}
public static void main(String args[]) {
XMLHandler xh = new XMLHandler();
xh.createXMLFile();
}
}

生成的XML文檔：

<?xml version="1.0" encoding="UTF-8" ?>

<country>
<china>
<city>Beijing</city>
<city>Shanghai</city>
</china>
</country>

3.DOM4J生成和解析XML文檔

DOM4J 是一個很是很是優秀的Java XML API，具備性能優異、功能強大和極端易用使用的特色，同時它也是一個開放源代碼的軟件。現在你能夠看到愈來愈多的 Java 軟件都在使用 DOM4J 來讀寫 XML，特別值得一提的是連 Sun 的JAXM 也在用 DOM4J。

（1）Dom4j解析XML文檔所使用到的jar包：dom4j.jar

（2）Dom4j文檔解釋示例代碼

package com.alisoft.facepay.framework.bean;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.Iterator;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
/**
*
* @author hongliang.dinghl Dom4j 生成XML文檔與解析XML文檔
*/
public class Dom4jDemo implements XmlDocument {
// Dom4j建立Xml文檔
public void createXml(String fileName) {
Document document = DocumentHelper.createDocument(); // 建立一個文檔對象
Element employees = document.addElement("employees"); // 在根節點添加元素
Element employee = employees.addElement("employee"); // 在employees下添加子節點
Element name = employee.addElement("name"); // 在employee下添加子節點
name.setText("ddvip"); // 給name節點添加內容
Element sex = employee.addElement("sex");
sex.setText("m");
Element age = employee.addElement("age");
age.setText("29");
try {
Writer fileWriter = new FileWriter(fileName);
XMLWriter xmlWriter = new XMLWriter(fileWriter);
xmlWriter.write(document);
xmlWriter.close();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
// Dom4j解釋Xml文檔
public void parserXml(String fileName) {
File inputXml = new File(fileName);
SAXReader saxReader = new SAXReader();
try {
Document document = saxReader.read(inputXml);
Element employees = document.getRootElement();
for (Iterator i = employees.elementIterator(); i.hasNext();) {
Element employee = (Element) i.next();
for (Iterator j = employee.elementIterator(); j.hasNext();) { // 遍例節點
Element node = (Element) j.next();
System.out.println(node.getName() + ":" + node.getText());
}
}
} catch (DocumentException e) {
System.out.println(e.getMessage());
}
System.out.println("dom4j parserXml");
}
}

4.JDOM生成和解析XML

爲減小DOM、SAX的編碼量，出現了JDOM；優勢：20-80原則，極大減小了代碼量。使用場合：要實現的功能簡單，如解析、建立等，但在底層，JDOM仍是使用SAX（最經常使用）、DOM、Xanan文檔。

（1）JDOM解析XML文檔所使用到的jar包：jdom.jar
（2）JDOM文檔解釋示例代碼

package com.alisoft.facepay.framework.bean;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;
/**
*
* @author hongliang.dinghl JDOM 生成與解析XML文檔
*
*/
public class JDomDemo implements XmlDocument {
public void createXml(String fileName) {
Document document;
Element root;
root = new Element("employees");
document = new Document(root);
Element employee = new Element("employee");
root.addContent(employee);
Element name = new Element("name");
name.setText("ddvip");
employee.addContent(name);
Element sex = new Element("sex");
sex.setText("m");
employee.addContent(sex);
Element age = new Element("age");
age.setText("23");
employee.addContent(age);
XMLOutputter XMLOut = new XMLOutputter();
try {
XMLOut.output(document, new FileOutputStream(fileName));
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public void parserXml(String fileName) {
SAXBuilder builder = new SAXBuilder(false);
try {
Document document = builder.build(fileName);
Element employees = document.getRootElement();
List employeeList = employees.getChildren();
// 獲取employee節點
for (int i = 0; i < employeeList.size(); i++) {
Element employee = (Element) employeeList.get(i);
List employeeInfo = employee.getChildren();
// 獲取employee節點下面的全部子節點
for(int j = 0; j < employeeInfo.size(); j++) {
Element info = (Element)employeeInfo.get(j);
System.out.println(info.getName() + ":" + info.getValue());
}
}
} catch (JDOMException e) {
System.out.println(e.getMessage());
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
}

比較

1）DOM4J性能最好，連Sun的JAXM也在用DOM4J.目前許多開源項目中大量採用DOM4J，例如大名鼎鼎的Hibernate也用DOM4J來讀取XML配置文件。若是不考慮可移植性，那就採用DOM4J.

2）JDOM和DOM在性能測試時表現不佳，在測試10M文檔時內存溢出。在小文檔狀況下還值得考慮使用DOM和JDOM.雖然JDOM的開發者已經說明他們指望在正式發行版前專一性能問題，可是從性能觀點來看，它確實沒有值得推薦之處。另外，DOM還是一個很是好的選擇。DOM實現普遍應用於多種編程語言。它仍是許多其它與XML相關的標準的基礎，由於它正式得到W3C推薦（與基於非標準的Java模型相對），因此在某些類型的項目中可能也須要它（如在JavaScript中使用DOM）。

3）SAX表現較好，這要依賴於它特定的解析方式－事件驅動。一個SAX檢測即將到來的XML流，但並無載入到內存（固然當XML流被讀入時，會有部分文檔暫時隱藏在內存中）。