使用 dom4j 比较两个xml文件内容，并输出结果

private Map<String, Element> removeDuplication(String filepath1, String filepath2, String rootName, String attrName) throws Exception {
        // 读取第一个xml
        Map<String, Element> map1 = readXml(filepath1, rootName, attrName);
        Set<String> set1 = map1.keySet();
        System.out.println(map1.keySet());
        // 读取第二个xml
        Map<String, Element> map2 = readXml(filepath2, rootName, attrName);
        Set<String> set2 = map2.keySet();
        System.out.println(map2.keySet());

        Map<String, Element> newMap = new TreeMap<>();
        // 第二个map根据第一个去重
        Sets.SetView<String> difference = Sets.difference(set2, set1);
        for (String s : difference) {
            newMap.put(s, map2.get(s));
        }
        return newMap;
    }

    private void writeXml(Map<String, Element> map, String filepath, String rootName) throws Exception {

        // 重写文件
        // 1. 创建Docuembnt
        Document doc = DocumentHelper.createDocument();
        // 2. 创建根元素
        Element root = doc.addElement(rootName);
        // root.addComment("文档的根city已经创建。");// 添加注释

        for (Map.Entry<String, Element> entry : map.entrySet()) {
            entry.getValue().setParent(null);
            root.add(entry.getValue());
            // entry.getValue().setParent(root);
            // doc.add(entry.getValue());
        }

        // 创建输出流
        Writer out = new PrintWriter(filepath, "utf-8");
        // 格式化
        OutputFormat format = new OutputFormat("    ", true);
        format.setTrimText(true);//去掉原来的空白(\t和换行和空格)！

        XMLWriter writer = new XMLWriter(out, format);
        // 把document对象写到out流中。
        writer.write(doc);

        out.close();
        writer.close();
    }

    /**
     * @param filepath 文件地址,全路径
     * @param rootName xml根名 "<root></root>"则 rootName 是 root
     * @param attrName 属性
     */
    private Map<String, Element> readXml(String filepath, String rootName, String attrName) throws Exception {
        Map<String, Element> map = new TreeMap<>();
        SAXReader reader = new SAXReader();
        // InputStream resourceAsStream = AttrParseTest.class.getResourceAsStream("/attrs.xml");
        // Document document = reader.read(resourceAsStream);
        File file = new File(filepath);
        Document document = reader.read(file);
        // <resources>
        Element resources = document.getRootElement();
        List<Element> attrElements = resources.elements();
        for (Element attrElement : attrElements) {
            List<Attribute> attrs = attrElement.attributes();
            for (Attribute attr : attrs) {
                if (attrName.equals(attr.getName())) {
                    map.put(attr.getValue(), attrElement);
                }
            }
        }
        return map;
    }