4-SIII-Android数据固化之Xml的Dom解析和存储

DOM将整个XML文件加载到内存中，并构建出节点树；
应用程序可以通过遍历节点树的方式来解析XML文件中的各个节点、属性等信息；
优点:对XML节点的添加修改等，而且解析也很方便
缺点比较耗费内存，解析速度也不快

<?xml version="1.0" encoding="UTF-8"?>
<weapons>
    <weapon material="玉" type="剑">
        <name>问天剑</name>
        <atk>2000</atk>
        <user>语熙华</user>
    </weapon>
    <weapon material="铁" type="刀">
        <name>皇刀</name>
        <atk>3000</atk>
        <user>九方玄玉</user>
    </weapon>
</weapons>

    /**
     * dom解析Xml
     * @return
     */
    private ArrayList<WeaponXml> parseXmlWithDom() {
         mWeapons = new ArrayList<>();
        InputStream is = null;

        try {
            is = getAssets().open("weapon.xml");
            //获取document对象
            Document dom = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(is);
            //获取根元素
            Element root = dom.getDocumentElement();
            //获取weapon节点
            NodeList weaponNode = root.getElementsByTagName("weapon");
            for (int i = 0; i < weaponNode.getLength(); i++) {
                mWeapon = new WeaponXml();
                //获取person下第i个元素
                Element weaponEl = (Element) weaponNode.item(i);
                String material = weaponEl.getAttribute("material");//得到第i个属性值
                String type = weaponEl.getAttribute("type");//得到第i个属性值

                mWeapon.setMaterial(material);
                mWeapon.setType(type);

                NodeList childNodes = weaponEl.getChildNodes();//获得获取weapon下子元素

                for (int j = 0; j < childNodes.getLength(); j++) {

                    if (childNodes.item(j).getNodeType() == Node.ELEMENT_NODE) {
                        String nodeName = childNodes.item(j).getNodeName();
                        if ("name".equals(nodeName)) {
                            String name = childNodes.item(j).getFirstChild().getNodeValue();
                            mWeapon.setName(name);
                        } else if ("atk".equals(nodeName)) {
                            String atk = childNodes.item(j).getFirstChild().getNodeValue();
                            mWeapon.setAtk(Integer.parseInt(atk));
                        } else if ("user".equals(nodeName)) {
                            String user = childNodes.item(j).getFirstChild().getNodeValue();
                            mWeapon.setUser(user);
                        }
                    }
                }
                mWeapons.add(mWeapon);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return mWeapons;
    }

    /**
     * sax创建Xml文件
     */
    private void domCreateXml() {
        try {
            ArrayList<WeaponXml> weaponXmls = parseXmlWithDom();

            //创建Dom解析器
            DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();

            //新建空白文档
            Document doc = builder.newDocument();
            //建立根元素employees
            Element root = doc.createElement("weapons");
            //将根节点添加进入文档
            doc.appendChild(root);

            for (WeaponXml weaponXml : weaponXmls) {
                Element weapon = doc.createElement("weapon");
                weapon.setAttribute("material", weaponXml.getMaterial());
                weapon.setAttribute("type", weaponXml.getType());
                root.appendChild(weapon);

                Element name = doc.createElement("name");
                name.appendChild(doc.createTextNode(weaponXml.getName()));
                weapon.appendChild(name);


                Element atk = doc.createElement("atk");
                atk.appendChild(doc.createTextNode(weaponXml.getAtk()+""));
                weapon.appendChild(atk);

                Element user = doc.createElement("user");
                user.appendChild(doc.createTextNode(weaponXml.getUser()));
                weapon.appendChild(user);
            }

            //为了得到xslt引擎创建对象
            TransformerFactory tff = TransformerFactory.newInstance();
            //创建xslt引擎对象输出xml文档
            Transformer tf = tff.newTransformer();
            //获取属性对象
            Properties pro = tf.getOutputProperties();
            //设置编码格式和输出格式
            pro.setProperty(OutputKeys.ENCODING, "utf-8");
            pro.setProperty(OutputKeys.METHOD, "xml");
            tf.setOutputProperties(pro);
            //创建资源对象
            DOMSource source = new DOMSource(doc);
            String path = Environment.getExternalStorageDirectory().getAbsolutePath()
                    +File.separator+"WeaponDom.xml";
            //获得输出对象
            StreamResult result = new StreamResult(new File(path));
            //执行dom文档到xml文件转换
            tf.transform(source, result);
        } catch (Exception e) {
            e.printStackTrace();
        }