DOM parsing XML
Dom parsing is to load all xml files into memory, assemble them into a dom tree, and then Parsing XML files through nodes and the relationship between nodes has nothing to do with the platform. Java provides a basic API for parsing XML files. It is relatively simple to understand, but because the entire document needs to be loaded into memory, it is not suitable for large documents. hour. (Recommended learning: java course)
SAX method to parse XML
Based on event-driven, one-by-one parsing, suitable for processing only xml data, not easy encoding, and it is difficult to access multiple different data in the same document at the same time
JDOM way to parse XML
Simplifies interaction with XML and is better than using DOM Faster to implement, using only concrete classes instead of interfaces thus simplifying the API and making it easy to parse XML using the
DOM4j way
An intelligence of JDOM Branch, more powerful, it is recommended to use
xml file proficiently
<?xml version="1.0" encoding="utf-8" ?> <class> <student> <firstname>cxx1</firstname> <lastname>Bob1</lastname> <nickname>stars1</nickname> <marks>85</marks> </student> <student rollno="493"> <firstname>cxx2</firstname> <lastname>Bob2</lastname> <nickname>stars2</nickname> <marks>85</marks> </student> <student rollno="593"> <firstname>cxx3</firstname> <lastname>Bob3</lastname> <nickname>stars3</nickname> <marks>85</marks> </student> </class>
DOM method
package com.cxx.xml; import org.w3c.dom.*; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; /** * @Author: cxx * Dom操作xml * @Date: 2018/5/29 20:19 */ public class DomDemo { //用Element方式 public static void element(NodeList list){ for (int i = 0; i <list.getLength() ; i++) { Element element = (Element) list.item(i); NodeList childNodes = element.getChildNodes(); for (int j = 0; j <childNodes.getLength() ; j++) { if (childNodes.item(j).getNodeType()==Node.ELEMENT_NODE) { //獲取節(jié)點(diǎn) System.out.print(childNodes.item(j).getNodeName() + ":"); //獲取節(jié)點(diǎn)值 System.out.println(childNodes.item(j).getFirstChild().getNodeValue()); } } } } public static void node(NodeList list){ for (int i = 0; i <list.getLength() ; i++) { Node node = list.item(i); NodeList childNodes = node.getChildNodes(); for (int j = 0; j <childNodes.getLength() ; j++) { if (childNodes.item(j).getNodeType()==Node.ELEMENT_NODE) { System.out.print(childNodes.item(j).getNodeName() + ":"); System.out.println(childNodes.item(j).getFirstChild().getNodeValue()); } } } } public static void main(String[] args) { //1.創(chuàng)建DocumentBuilderFactory對(duì)象 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); //2.創(chuàng)建DocumentBuilder對(duì)象 try { DocumentBuilder builder = factory.newDocumentBuilder(); Document d = builder.parse("src/main/resources/demo.xml"); NodeList sList = d.getElementsByTagName("student"); //element(sList); node(sList); } catch (Exception e) { e.printStackTrace(); } } }
SAX method
package com.cxx.xml; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; /** * @Author: cxx * SAX解析DOM * 一行一行 Handler * startElement * endElement * @Date: 2018/5/29 20:03 */ public class SaxDemo { public static void main(String[] args) throws Exception { //1.或去SAXParserFactory實(shí)例 SAXParserFactory factory = SAXParserFactory.newInstance(); //2.獲取SAXparser實(shí)例 SAXParser saxParser = factory.newSAXParser(); //創(chuàng)建Handel對(duì)象 SAXDemoHandel handel = new SAXDemoHandel(); saxParser.parse("src/main/resources/demo.xml",handel); } } class SAXDemoHandel extends DefaultHandler { //遍歷xml文件開始標(biāo)簽 @Override public void startDocument() throws SAXException { super.startDocument(); System.out.println("sax解析開始"); } //遍歷xml文件結(jié)束標(biāo)簽 @Override public void endDocument() throws SAXException { super.endDocument(); System.out.println("sax解析結(jié)束"); } @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { super.startElement(uri, localName, qName, attributes); if (qName.equals("student")){ System.out.println("============開始遍歷student============="); //System.out.println(attributes.getValue("rollno")); } else if (!qName.equals("student")&&!qName.equals("class")){ System.out.print("節(jié)點(diǎn)名稱:"+qName+"----"); } } @Override public void endElement(String uri, String localName, String qName) throws SAXException { super.endElement(uri, localName, qName); if (qName.equals("student")){ System.out.println(qName+"遍歷結(jié)束"); System.out.println("============結(jié)束遍歷student============="); } } @Override public void characters(char[] ch, int start, int length) throws SAXException { super.characters(ch, start, length); String value = new String(ch,start,length).trim(); if (!value.equals("")) { System.out.println(value); } } }
JDOM way
<!--jdom --> <dependency> <groupId>org.jdom</groupId> <artifactId>jdom</artifactId> <version>1.1.3</version> </dependency>
package com.cxx.xml; import org.jdom.Attribute; import org.jdom.Document; import org.jdom.Element; import org.jdom.input.SAXBuilder; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.InputStream; import java.util.List; /** * @Author: cxx * JDom解析xml * 快速開發(fā)XML應(yīng)用程序。 * 是一個(gè)開源項(xiàng)目 * JDOM主要用來彌補(bǔ)DOM和SAX在實(shí)際應(yīng)用當(dāng)中的不足。 * @Date: 2018/5/30 11:44 */ public class JDomDemo { public static void main(String[] args) throws Exception { //1.創(chuàng)建SAXBuilder對(duì)象 SAXBuilder saxBuilder = new SAXBuilder(); //2.創(chuàng)建輸入流 InputStream is = new FileInputStream(new File("src/main/resources/demo.xml")); //3.將輸入流加載到build中 Document document = saxBuilder.build(is); //4.獲取根節(jié)點(diǎn) Element rootElement = document.getRootElement(); //5.獲取子節(jié)點(diǎn) List<Element> children = rootElement.getChildren(); for (Element child : children) { System.out.println("通過rollno獲取屬性值:"+child.getAttribute("rollno")); List<Attribute> attributes = child.getAttributes(); //打印屬性 for (Attribute attr : attributes) { System.out.println(attr.getName()+":"+attr.getValue()); } List<Element> childrenList = child.getChildren(); System.out.println("======獲取子節(jié)點(diǎn)-start======"); for (Element o : childrenList) { System.out.println("節(jié)點(diǎn)名:"+o.getName()+"---"+"節(jié)點(diǎn)值:"+o.getValue()); } System.out.println("======獲取子節(jié)點(diǎn)-end======"); } } }
DOM4J way
<!-- dom4j --> <dependency> <groupId>dom4j</groupId> <artifactId>dom4j</artifactId> <version>1.6.1</version> </dependency>
package com.cxx.xml; import org.dom4j.Attribute; import org.dom4j.Document; import org.dom4j.DocumentException; import org.dom4j.Element; import org.dom4j.io.SAXReader; import java.io.File; import java.util.Iterator; import java.util.List; /** * @Author: cxx * Dom4j解析xml * @Date: 2018/5/30 12:21 */ public class Dom4JDemo { public static void main(String[] args) throws Exception { //1.創(chuàng)建Reader對(duì)象 SAXReader reader = new SAXReader(); //2.加載xml Document document = reader.read(new File("src/main/resources/demo.xml")); //3.獲取根節(jié)點(diǎn) Element rootElement = document.getRootElement(); Iterator iterator = rootElement.elementIterator(); while (iterator.hasNext()){ Element stu = (Element) iterator.next(); List<Attribute> attributes = stu.attributes(); System.out.println("======獲取屬性值======"); for (Attribute attribute : attributes) { System.out.println(attribute.getValue()); } System.out.println("======遍歷子節(jié)點(diǎn)======"); Iterator iterator1 = stu.elementIterator(); while (iterator1.hasNext()){ Element stuChild = (Element) iterator1.next(); System.out.println("節(jié)點(diǎn)名:"+stuChild.getName()+"---節(jié)點(diǎn)值:"+stuChild.getStringValue()); } } } }
The above is the detailed content of How to parse XML in java. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

The key to writing PHP comments is to clarify the purpose and specifications. Comments should explain "why" rather than "what was done", avoiding redundancy or too simplicity. 1. Use a unified format, such as docblock (/*/) for class and method descriptions to improve readability and tool compatibility; 2. Emphasize the reasons behind the logic, such as why JS jumps need to be output manually; 3. Add an overview description before complex code, describe the process in steps, and help understand the overall idea; 4. Use TODO and FIXME rationally to mark to-do items and problems to facilitate subsequent tracking and collaboration. Good annotations can reduce communication costs and improve code maintenance efficiency.

Comments cannot be careless because they want to explain the reasons for the existence of the code rather than the functions, such as compatibility with old interfaces or third-party restrictions, otherwise people who read the code can only rely on guessing. The areas that must be commented include complex conditional judgments, special error handling logic, and temporary bypass restrictions. A more practical way to write comments is to select single-line comments or block comments based on the scene. Use document block comments to explain parameters and return values at the beginning of functions, classes, and files, and keep comments updated. For complex logic, you can add a line to the previous one to summarize the overall intention. At the same time, do not use comments to seal code, but use version control tools.

The key to writing good comments is to explain "why" rather than just "what was done" to improve the readability of the code. 1. Comments should explain logical reasons, such as considerations behind value selection or processing; 2. Use paragraph annotations for complex logic to summarize the overall idea of functions or algorithms; 3. Regularly maintain comments to ensure consistency with the code, avoid misleading, and delete outdated content if necessary; 4. Synchronously check comments when reviewing the code, and record public logic through documents to reduce the burden of code comments.

The first step is to select the integrated environment package XAMPP or MAMP to build a local server; the second step is to select the appropriate PHP version according to the project needs and configure multiple version switching; the third step is to select VSCode or PhpStorm as the editor and debug with Xdebug; in addition, you need to install Composer, PHP_CodeSniffer, PHPUnit and other tools to assist in development.

The key to writing PHP comments is clear, useful and concise. 1. Comments should explain the intention behind the code rather than just describing the code itself, such as explaining the logical purpose of complex conditional judgments; 2. Add comments to key scenarios such as magic values, old code compatibility, API interfaces, etc. to improve readability; 3. Avoid duplicate code content, keep it concise and specific, and use standard formats such as PHPDoc; 4. Comments should be updated synchronously with the code to ensure accuracy. Good comments should be thought from the perspective of others, reduce the cost of understanding, and become a code understanding navigation device.

There are three common ways to use PHP comments: single-line comments are suitable for briefly explaining code logic, such as // or # for the explanation of the current line; multi-line comments /*...*/ are suitable for detailed description of the functions or classes; document comments DocBlock start with /** to provide prompt information for the IDE. When using it, you should avoid nonsense, keep updating synchronously, and do not use comments to block codes for a long time.

PHP comparison operators need to pay attention to type conversion issues. 1. Use == to compare values only, and type conversion will be performed, such as 1=="1" is true; 2. Use === to require the same value as the type, such as 1==="1" is false; 3. Size comparison can be used on values and strings, such as "apple"

PHP comments are parts of the code that are used to interpret logic, tag tasks, or temporarily block code and are not executed by the server. Its core functions include: 1. Improve the readability of the code, which facilitates quick understanding of others and future self; 2. Supports two formats: single-line comments (// or #) and multi-line comments (//); 3. Common uses cover function descriptions, complex logic explanations, TODO markings and disable code during debugging; 4. Effective comments should avoid duplicate code, explain the reasons rather than operations, keep it concise and add version records where necessary, thereby significantly improving code maintenance efficiency.
