XML文件的应用

/**
 * 遍历XML中的文件
 */
public class XMLTest {
    public static void main(String[] args) throws Exception {
        //1、解析器工厂类
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        //2、解析器对象
        DocumentBuilder builder = factory.newDocumentBuilder();
        //3、指向硬盘文件，形成Document对象
        Document document = builder.parse("src/books.xml");
        // 4、
        NodeList list = document.getElementsByTagName("book");
        for(int i=0;i<list.getLength();i++){
            Element book = (Element)list.item(i);
            String bookId = book.getAttribute("id");
            String bookTypeId = book.getAttribute("type");            
            String bookName = book.getElementsByTagName("bookName").item(0).getFirstChild().getNodeValue();
            String bookPrice = book.getElementsByTagName("bookPrice").item(0).getFirstChild().getNodeValue();
            System.out.println(bookId+"\t"+bookTypeId+"\t"+bookName+"\t"+bookPrice);
            System.out.println();
            
        }
    }
}

/**
 * 向XML文件中增加元素，修改元素
 *
 */
public class Test {
    public static void main(String[] args) throws Exception {
        addXml();
        modifyXML();
    }

    private static void modifyXML() throws Exception {
        // 1、构建工厂
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

        // 2、构建器
        DocumentBuilder builder = factory.newDocumentBuilder();

        // 3、parse（路径）解析哪个文件，幻化成内存中的一个对象，形态做了改变
        Document document = builder.parse("src/books.xml");

        // 4、获取子节点，一本一本图书
        NodeList list = document.getElementsByTagName("book");

        Element book = (Element) list.item(0);
        book.getElementsByTagName("bookName").item(0)
                .setTextContent("Html和CSS-谭浩强");

        // 6.document write 硬盘上
        // Transfer 传输、转移 内存---------->Disk硬盘上
        TransformerFactory factory2 = TransformerFactory.newInstance();
        Transformer transformer = factory2.newTransformer();
        Source source = new DOMSource(document);
        Result result = new StreamResult("src/books.xml");
        transformer.transform(source, result);

        System.out.println("success");
    }

    public static void addXml() throws Exception {
        // 添加一本书，要求属性id type
        // 1、工厂
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

        // 2、解析器Builder
        DocumentBuilder builder = factory.newDocumentBuilder();

        // 3、parese 解析出来Document
        Document document = builder.parse("src/books.xml");

        // 4、在内存中构建出一个游离的Book对象
        Element book = document.createElement("book");
        book.setAttribute("id", "004");
        book.setAttribute("type", "4");

        Element bookName = document.createElement("bookName");
        bookName.setTextContent("你是人间的四月天");

        Element bookPrice = document.createElement("bookPrice");
        bookPrice.setTextContent("86");

        Element bookAuthor = document.createElement("bookAuthor");
        bookAuthor.setTextContent("林徽因");

        Element bookPublisher = document.createElement("bookPublisher");
        bookPublisher.setTextContent("徐志摩出版社");

        // 4.1 绑定
        book.appendChild(bookName);
        book.appendChild(bookPrice);
        book.appendChild(bookAuthor);
        book.appendChild(bookPublisher);

        // 4.2将book对象和books绑定，作为他的子节点

        // 5、将游离的book对象 隶属于books的子节点
        document.getElementsByTagName("books").item(0).appendChild(book);

        // 6.document write 硬盘上
        // Transfer 传输、转移 内存---------->Disk硬盘上
        TransformerFactory factory2 = TransformerFactory.newInstance();
        Transformer transformer = factory2.newTransformer();
        Source source = new DOMSource(document);
        Result result = new StreamResult("src/books.xml");
        transformer.transform(source, result);
        System.out.println("addOk");
    }
}

二、使用DOM4J遍历XML中的内容

public class MyDom4j {
    public static void main(String[] args) throws Exception {
        // 1、构建一个解析器
        SAXReader reader = new SAXReader();
        
        //2、获取到整个文档对象
        Document document = reader.read("src/books.xml");
        
        // 3、获取到根节点
        Element root = document.getRootElement();
        
        // 4、获取到根节点的子节点集合
        List<Element> books = root.elements();
        
        for(Element element:books){
            // 5、一个element代表一本书
            String bookName = element.element("bookName").getText();
            System.out.println(bookName);
        }
    }
}

 三、使用DOM4J向XML中添加内容

public class MyMain {
    public static void main(String[] args) throws Exception {
        addXML();
    }

    private static void addXML() throws Exception {
        SAXReader reader = new SAXReader();
        //2、获取到整个文档对象
        Document document = reader.read("src/books.xml");
        //3、获取到根节点
        Element root = document.getRootElement();
        // 拿到了根节点
        // 操作
        Element book = DocumentHelper.createElement("book");
        // 过时的方法
        book.setAttributeValue("id", "005");
　　　　 // 新方法
        book.addAttribute("type","5");
        
        //图书名称
        Element bookName = DocumentHelper.createElement("bookName");
        bookName.setText("资治通鉴");
        
        // 关系，绑定一下
        book.add(bookName);
        
        //将book和整个根节点绑定
        root.add(book);
        
        // 将内存中有层级关系的节点放入到硬盘上
        OutputStream os = new FileOutputStream("src/books.xml");
        Writer writer = new OutputStreamWriter(os,"utf-8"); 
        document.write(writer);
        writer.close();
        System.out.println("写入成功！");
    }
}