廖雪峰Java14Java操作XML和JSON-1XML-2DOM

DOM：
Document Object Model
DOM模型就是把XML文档作为一个树形结构，从根结点开始，每个节点都可以包含任意个字节点。

用Java解析XML时，
Document代表整个XML文档
Element表示元素
Attribute：属性

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document doc = db.parse(XML_URL);
        Element root = doc.getDocumentElement();

import org.w3c.dom.Document;
import org.w3c.dom.Node;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

public class DomSample {
    static final  String XML_URL = "http://rss.sina.com.cn/tech/internet/home28.xml";
    public static void main(String[] args) throws Exception{
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document doc = db.parse(XML_URL);
        printNode(doc,0);
    }
    static void printNode(Node n, int indent){
        for(int i=0;i<indent;i++){
            System.out.print(' ');
        }
        switch (n.getNodeType()){
            case Node.DOCUMENT_NODE:
                System.out.println("Document:"+n.getNodeName());
                break;
            case Node.ELEMENT_NODE:
                System.out.println("Element:"+n.getNodeName());
                break;
            case Node.TEXT_NODE:
                System.out.println("Text:"+n.getNodeName()+"="+n.getNodeValue());
                break;
            case Node.ATTRIBUTE_NODE:
                System.out.println("Attr:"+n.getNodeName()+"="+n.getNodeValue());
                break;
            case Node.CDATA_SECTION_NODE:
                System.out.println("CDATA:"+n.getNodeName()+"="+n.getNodeValue());
                break;
            case Node.COMMENT_NODE:
                System.out.println("Commment:"+n.getNodeName()+"="+n.getNodeValue());
                break;
            default:
                System.out.println("NodeType:"+n.getNodeType()+",NodeName:"+n.getNodeName());
        }
        for(Node child=n.getFirstChild();child != null;child=child.getNextSibling()){
            printNode(child,indent+1);
        }
    }
}

总结：

Java DOM API：

• 将XML解析为DOM
• 可在内存中完整表示XML数据结构
• 解析速度慢，内存占用大

原文地址：https://www.cnblogs.com/csj2018/p/11379284.html