Java 操作XML工具类-优快云博客

本文链接：https://blog.youkuaiyun.com/Kedongyu_/article/details/98207392

本文介绍了一种使用Java进行XML配置文件读写的实现方法，包括导入必要的xml-apis库，通过单例模式创建SettingDoc类，该类提供了一系列用于查找、判断节点存在性和保存XML文档的方法。

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1.导入jar 包

<!-- https://mvnrepository.com/artifact/xml-apis/xml-apis -->
<dependency>
    <groupId>xml-apis</groupId>
    <artifactId>xml-apis</artifactId>
    <version>1.4.01</version>
</dependency>

2.编写代码


public class SettingDoc {

    private Document doc;

    private String path;

    /**
     * 单例模式
     */
    private static SettingDoc instance;

    private SettingDoc() {
    }

    /**
     * 创建实例
     * @return
     */
    public static SettingDoc getInstance() {
        if (instance == null) {
            synchronized (SettingDoc.class) {
                if(instance == null) {
                    instance = new SettingDoc();
                    //       ProjectManager projectManager =ProjectManager.getInstance();
                    //       Project[] projects = projectManager.getOpenProjects();
                    instance.path = "setting.xml";
                    //       if(projects.length > 0) {
                    //           instance.path = projects[0].getBasePath().toString() + "/setting.xml";
                    //        }
                    File file = new File(instance.path);
                    System.out.println(file.getAbsolutePath());

                    if (!file.exists()) {
                        try {
                            file.createNewFile();
                            PrintWriter printWriter = new PrintWriter(new FileWriter(file, true), false);//第二个参数为true，从文件末尾写入 为false则从开头写入
                            printWriter.println("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                                    "<settings></settings>");
                            printWriter.close();//记得关闭输入流
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    SAXReader reader = new SAXReader();
                    try {
                        instance.doc = reader.read(file);
                    } catch (DocumentException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
        return instance;
    }

    public Document getDoc() {
        return doc;
    }

    public Node findElement(Node node, String nodeName) {
        if (nodeName == null || nodeName.trim().equals("") || node == null) {
            return null;
        }
        if (nodeName.equals(node.getName())) {
            return node;
        }
        if (node instanceof Element) {
            Element element = (Element) node;
            if (element.nodeCount() > 0) {
                for (int i = 0; i < element.nodeCount(); i++) {
                    Node result = findElement(element.node(i), nodeName);
                    if (result != null)
                        return result;
                }
                return null;
            }
        }
        return null;
    }

    public Node findElement(String nodeName) {
        return findElement(doc.getRootElement(), nodeName);
    }


    public Node findElementByNodePath(String nodePath){
        if(nodePath == null||nodePath.trim().equals("")){
            return null;
        }
        String[] nodeNames = nodePath.split("/");
        int i = 0;
        if(nodeNames.length > 1 &&"".equals(nodeNames[0])){
            i = 1;
        }
        Element element = null;
        for(int j = 0;i<nodeNames.length;i++,j++){
            if(j == 0)
                element = doc.getRootElement();
            else
                element = element.element(nodeNames[i]);
            if(element == null){
                return null;
            }
        }
        return element;
    }

    /**
     * 判断是否有某个结点
     * @param nodeName
     * @return
     */
    public boolean hasNode(String nodeName) {
        Node node = findElement(doc.getRootElement(), nodeName);
        return node != null;
    }

    /**
     * 保存数据到xml文档
     */
    public void save() {
        OutputFormat format = OutputFormat.createCompactFormat();
        format.setEncoding("UTF-8");
        XMLWriter writer = null;
        try {
            writer = new XMLWriter(new FileOutputStream(path), format);
            writer.write(doc);
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        SettingDoc settingDoc = SettingDoc.getInstance();
        System.out.println(settingDoc.findElementByNodePath("/settings/filePath/controller").getText());
    }
}