最近又用到XML,发现也有必要聊聊XML的几种方式。
1,如果只是简单生成或者解析,自己写一个帮助类就行,下面这个是我前段时间用递归写的,优势方便可以扩展
import java.util.ArrayList;
import java.util.List;
/**
*
* @author hejinbin1987@
*
* TODO manage node and value.and format the node to xml file
*
*/
public class XMLSimpleNode implements SimpleNode {
private String nodeName;
private String value;
List<SimpleNode> childs;
private String header;
public XMLSimpleNode(String nodeName) {
this.nodeName = nodeName;
childs = new ArrayList<SimpleNode>(2);
}
public String getNodeName() {
return nodeName;
}
/*
* (non-Javadoc)
*
* @see org.benson.another.SimpleXMLFileUtil#setNodeName(java.lang.String)
*/
public void setNodeName(String nodeName) {
this.nodeName = nodeName;
}
public String getValue() {
return value;
}
/*
* (non-Javadoc)
*
* @see org.benson.another.SimpleXMLFileUtil#setValue(java.lang.String)
*/
public void setValue(String value) {
this.value = value;
}
/*
* (non-Javadoc)
*
* @see org.benson.another.SimpleXMLFileUtil#addChild(org.benson.another.XMLItem)
*/
public void addChild(SimpleNode node) {
childs.add(node);
}
public String startTag() {
StringBuffer tagSart = new StringBuffer("<");
tagSart.append(nodeName);
tagSart.append(">");
return tagSart.toString();
}
public String endTag() {
StringBuffer tagEnd = new StringBuffer("</");
tagEnd.append(nodeName);
tagEnd.append(">");
return tagEnd.toString();
}
public String getHeader() {
return header;
}
/*
* (non-Javadoc)
*
* @see org.benson.another.SimpleXMLFileUtil#setHeader(java.lang.String)
*/
public void setHeader(String header) {
this.header = header;
}
/**
* ToDo format the node to xml file
*/
public String formartXMLFile() {
StringBuffer xmlFileBf = new StringBuffer();
xmlFileBf.append(this.getHeader());
return this.getNode(this, xmlFileBf).toString();
}
/**
*
* @param node
* @param xmlFileBf
* @return get XML content by node
*/
private StringBuffer getNode(SimpleNode node, StringBuffer xmlFileBf) {
XMLSimpleNode xmlNode = (XMLSimpleNode) node;
XMLSimpleNode xmlNodeItem = null;
xmlFileBf.append(xmlNode.startTag());
if (xmlNode.childs.size() != 0) {
for (int i = 0; i < xmlNode.childs.size(); i++) {
xmlNodeItem = (XMLSimpleNode) xmlNode.childs.get(i);
getNode(xmlNodeItem, xmlFileBf);
}
}
if (xmlNode.getValue() != null)
xmlFileBf.append(xmlNode.getValue());
xmlFileBf.append(xmlNode.endTag());
return xmlFileBf;
}
public static void main(String[] args) {
SimpleNode xmlNode = new XMLSimpleNode("root");
xmlNode.setHeader("<?xml version=\"1.0\" encoding=\"UTF-8\" ?> ");
SimpleNode chridNode1 = new XMLSimpleNode("chrid1");
SimpleNode chridNode2 = new XMLSimpleNode("chrid2");
SimpleNode chridNode3 = new XMLSimpleNode("chrid3");
SimpleNode chridNode11 = new XMLSimpleNode("chrid11");
SimpleNode chridNode12 = new XMLSimpleNode("chrid12");
SimpleNode chridNode13 = new XMLSimpleNode("chrid13");
chridNode11.setValue("chridNode11 Value");
chridNode12.setValue("chridNode12 Value");
chridNode13.setValue("chridNode13 Value");
chridNode2.setValue("chridNode2 Value");
chridNode3.setValue("chridNode3 value");
chridNode1.addChild(chridNode11);
chridNode1.addChild(chridNode12);
chridNode1.addChild(chridNode13);
xmlNode.addChild(chridNode1);
xmlNode.addChild(chridNode2);
xmlNode.addChild(chridNode3);
System.out.println(xmlNode.formartXMLFile());
}
}
输出结果如下
<?xml version="1.0" encoding="UTF-8" ?> <root><chrid1><chrid11>chridNode11 Value</chrid11><chrid12>chridNode12 Value</chrid12><chrid13>chridNode13 Value</chrid13></chrid1><chrid2></chrid2><chrid3></chrid3></root>其实个人感觉和jdom就有点类似了,扩展下就好了
2,用DOM,这个东西也是把XML组成树,然后放进内存中,但是遵循了w3c的原则,方便移植,兼容性好,你可以切换各种实现方式如,Xerces,或者Crimon,再或者其它,修改jaxp.propertie,JDK默认是Xerces。
缺点也很明显,一次性加载进内存,容易造成内存溢出,API也不好用,不支持接点的随机访问
顺便说句,最近看源码发现spring就是用这个做配置文件解析的 附2. spring中IOC的实现源码篇【analyze spring framework source】,所以当spring配置文件过多时也会报out memory了
注意:没找到?因为sun的JDK默认是不存在的,IBM的JDK存在,新建一个就行 ,
放在 ${JAVA_HOME}/lib/jaxp.properties,
修改成 javax.xml.parsers.SAXParserFactory=org.apache.xerces.jaxp.SAXParserFactoryImpl
常见IBM JDK兼容性错误,一般也是这个原因引起:
javax.xml.parsers.FactoryConfigurationError: Provider null could not be instantiated:
java.lang.NullPointerException
3.jdom ,这个也是基于DOM实现的,但其API比DOM好用,更灵活,不是标准W3C
4.SAX,这个是逐行解析和构建XML文件,优点就是不用把XML整个结构都加进内存,适用于大批量的XML文件导入导出,缺点:每次都要去读文件,肯定没有直接内存里速度快了
附上:SAXP解析XML的笔记 挺详细的
5.DOM4J,原来是JDOM的分支,现独立开发,处于JDOM于SAX之间,即支持把XML放进内存,但可以读取时选择性删除DOM节点减少内存使用,所以也可以处理大数据XML文件,传说hibernate的配置文件也是基于dom4J(没看hibernate源码)
优点,提供读取事件处理,提供Visitor处理,也可以处理大数据XML文件(每次读完节点后删除)当然处理大数据咋样也不如SAX节省内存了,毕竟要读完一个element才会触发
百度百科的介绍的不错 http://baike.baidu.com/view/1460716.htm
show you the code. 下面就是分别用这4中方法读写XML
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Iterator;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamWriter;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.dom4j.ElementHandler;
import org.dom4j.ElementPath;
import .SAXReader;
import .XMLWriter;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
/**
*
* @author Love Eat large meat bun
* @TD use the SAX DOM JDOM to build and parser xml file
* @email hejinbin1987@
*/
public class Test4XML extends DefaultHandler implements ElementHandler {
private String tagName = "";
public static final String FILE_PATH = "D://saxText.xml";
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
System.out.println(tagName + "===SAX===>" + new String(ch, start, length));
}
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
tagName = qName;
}
public static void removeFile() {
System.out.println("the file have be delete is " + new File(FILE_PATH).delete());
}
@Override
public void onEnd(ElementPath paramElementPath) {
// TODO print node
org.dom4j.Element ele=paramElementPath.getCurrent();
System.out.println(ele.getName()+"===DOM4J====>"+ele.getText());
ele.detach();//after read /root/user node .remove it from memory,avoid out of memory
}
@Override
public void onStart(ElementPath paramElementPath) {
}
public void writeXMLByDOM() throws Exception {
DocumentBuilderFactory buildFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = buildFactory.newDocumentBuilder();
Document doc = documentBuilder.newDocument();
Element ele = doc.createElement("root");
Element ele1 = doc.createElement("user");
ele1.setTextContent("largeMeatBun");
ele.appendChild(ele1);
Element ele2 = doc.createElement("email");
ele2.setTextContent("hejinbin1987@");
ele.appendChild(ele2);
doc.appendChild(ele);
DOMSource xmlSource = new DOMSource(doc);
TransformerFactory transFactory = TransformerFactory.newInstance();
Transformer transformer = transFactory.newTransformer();
FileOutputStream outputTarget = new FileOutputStream(FILE_PATH);
transformer.transform(xmlSource, new StreamResult(outputTarget));
outputTarget.close();//the output steam can't auto to close
}
public void readerDOMParseXML() throws Exception {
DocumentBuilderFactory buildFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = buildFactory.newDocumentBuilder();
FileInputStream file = new FileInputStream(FILE_PATH);
Document document = documentBuilder.parse(file);
file.close();//the xml data have load in memory
Element node = document.getDocumentElement();
NodeList nodelist = node.getChildNodes();
for (int i = 0; i < nodelist.getLength(); i++)
System.out.println(nodelist.item(i).getNodeName() + "===DOM===>" + nodelist.item(i).getTextContent());
}
public void writeXMLBySAX() throws Exception {
//sax writer
OutputStream SAXOut = new FileOutputStream(FILE_PATH);
XMLStreamWriter xmlWrite = XMLOutputFactory.newInstance().createXMLStreamWriter(SAXOut);
xmlWrite.writeStartDocument("utf-8", "1.0");
xmlWrite.writeStartElement("root");
xmlWrite.writeStartElement("user");
xmlWrite.writeCharacters("largeMeatBun");
xmlWrite.writeEndElement();
xmlWrite.writeStartElement("email");
xmlWrite.writeCharacters("hejinbin1987@");
xmlWrite.writeEndElement();
xmlWrite.writeEndElement();
xmlWrite.writeEndDocument();
xmlWrite.close();
SAXOut.close();
}
public void parseXMLbySAX() throws Exception {
//sax parser
InputStream SAXIn = new FileInputStream(FILE_PATH);
SAXParser saxParser = SAXParserFactory.newInstance().newSAXParser();
saxParser.parse(SAXIn, this);
}
public org.jdom.Document readXMLByJDOM() throws Exception {
FileInputStream JDOMInput = new FileInputStream(FILE_PATH);
org.jdom.Document doc = new SAXBuilder().build(JDOMInput);
org.jdom.Element eleRoot = doc.getRootElement();
List<org.jdom.Element> eleJDOMList = eleRoot.getChildren();
for (org.jdom.Element eleJDOM : eleJDOMList) {
System.out.println(eleJDOM.getName() + "====JDOM===>" + eleJDOM.getText());
}
return doc;
}
public void writeXMLByJDOM(org.jdom.Document doc) throws Exception {
FileOutputStream JDOMOut = new FileOutputStream(FILE_PATH);
new XMLOutputter().output(doc, JDOMOut);
JDOMOut.close();
}
public org.dom4j.Document readXMLByDOM4J() throws Exception {
SAXReader saxReadernew =new SAXReader();
saxReadernew.addHandler("/root/user", this);
org.dom4j.Document docD4J = saxReadernew.read(FILE_PATH);
org.dom4j.Element rootD4E = docD4J.getRootElement();
Iterator<org.dom4j.Element> iterD4E = rootD4E.elementIterator();
while (iterD4E.hasNext()) {
org.dom4j.Element eleD4E = iterD4E.next();
System.out.println(eleD4E.getName() + "===DOM4J===>" + eleD4E.getText());
}
return docD4J;
}
public void writeXMLByDOM4J(org.dom4j.Document docD4J) throws Exception {
FileOutputStream DOM4JOut = new FileOutputStream(FILE_PATH);
XMLWriter writer = new XMLWriter(DOM4JOut);
writer.write(docD4J);
DOM4JOut.close();
}
public static void main(String[] args) throws Exception {
/**
* dom you can change the implement class any one you like in jaxp.properties
*/
//dom writer and parser
Test4XML test4Xml = new Test4XML();
test4Xml.writeXMLByDOM();
test4Xml.readerDOMParseXML();
/**
* SAX help doc http:///DocWeb/api/all/javax.xml.stream.XMLStreamWriter
*/
removeFile();
test4Xml.writeXMLBySAX();
test4Xml.parseXMLbySAX();
/**
* @see http://www.jdom.org/ to find api on jdom web
*/
org.jdom.Document doc = test4Xml.readXMLByJDOM();
removeFile();
test4Xml.writeXMLByJDOM(doc);
/**
* @see http://www.dom4j.org/
*/
org.dom4j.Document docDOM4J = test4Xml.readXMLByDOM4J();
test4Xml.writeXMLByDOM4J(docDOM4J);
// removeFile();
}
}6.其它开源项目,比如xstream等
















