Java Dom解析xml

 

Java Dom解析xml

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>

<?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;
    }
}

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;
    }
}

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());
        }
    }
}