Dom解析是将xml文件全部载入,组装成一颗dom树,然后通过节点以及节点之间的关系来解析xml文件,下面结合这个xml文件来进行dom解析。
- <?xml version="1.0" encoding="UTF-8"?>
- <books>
- <book id="12">
- <name>thinking in java</name>
- <price>85.5</price>
- </book>
- <book id="15">
- <name>Spring in Action</name>
- <price>39.0</price>
- </book>
- </books>
然后结合一张图来发现dom解析时需要注意的地方
在这里当我们得到节点book时,也就是图中1所画的地方,如果我们调用它的getChildNodes()方法,大家猜猜它的子节点有几个?不包
括它的孙子节点,thinking in
java这种的除外,因为它是孙子节点。它总共有5个子节点,分别是图中2、3、4、5、6所示的那样。所以在解析时,一定要小心,不要忽略空白的地方。
然后看代码来解析book.xml文件
DomParseService.java
- import java.io.InputStream;
- import java.util.ArrayList;
- import java.util.List;
- import javax.xml.parsers.DocumentBuilder;
- import javax.xml.parsers.DocumentBuilderFactory;
- import org.w3c.dom.Document;
- import org.w3c.dom.Element;
- import org.w3c.dom.NodeList;
- import org.w3c.dom.Node;
- import com.xtlh.cn.entity.Book;
- public class DomParseService {
- public List<Book> getBooks(InputStream inputStream) throws Exception{
- List<Book> list = new ArrayList<Book>();
- DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
- DocumentBuilder builder = factory.newDocumentBuilder();
- Document document = builder.parse(inputStream);
- Element element = document.getDocumentElement();
- NodeList bookNodes = element.getElementsByTagName("book");
- for(int i=0;i<bookNodes.getLength();i++){
- Element bookElement = (Element) bookNodes.item(i);
- Book book = new Book();
- book.setId(Integer.parseInt(bookElement.getAttribute("id")));
- NodeList childNodes = bookElement.getChildNodes();
- // System.out.println("*****"+childNodes.getLength());
- for(int j=0;j<childNodes.getLength();j++){
- if(childNodes.item(j).getNodeType()==Node.ELEMENT_NODE){
- if("name".equals(childNodes.item(j).getNodeName())){
- book.setName(childNodes.item(j).getFirstChild().getNodeValue());
- }else if("price".equals(childNodes.item(j).getNodeName())){
- book.setPrice(Float.parseFloat(childNodes.item(j).getFirstChild().getNodeValue()));
- }
- }
- }//end for j
- list.add(book);
- }//end for i
- return list;
- }
- }
Book.java用来组装数据和盛放数据
- public class Book {
- private int id;
- private String name;
- private float price;
- public int getId() {
- return id;
- }
- public void setId(int id) {
- this.id = id;
- }
- public String getName() {
- return name;
- }
- public void setName(String name) {
- this.name = name;
- }
- public float getPrice() {
- return price;
- }
- public void setPrice(float price) {
- this.price = price;
- }
- @Override
- public String toString(){
- return this.id+":"+this.name+":"+this.price;
- }
- }
测试使用单元测试如下ParseTest.java
- public class ParseTest extends TestCase{
- public void testDom() throws Exception{
- InputStream input = this.getClass().getClassLoader().getResourceAsStream("book.xml");
- DomParseService dom = new DomParseService();
- List<Book> books = dom.getBooks(input);
- for(Book book : books){
- System.out.println(book.toString());
- }
- }
- }