2-SIII-Android数据固化之Xml的Pull解析和存储

Pull是安卓内置的，基于事件触发的解析器
Pull解析器小巧轻便，解析速度快，简单易用
主动从解析器中获取事件，可以在满足了需要的条件后不再获取事件，结束解析

<?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>

private ArrayList<WeaponXml> parseXmlWithPull() {
    InputStream is = null;
    try {
        //XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
        //XmlPullParser pullParser = factory.newPullParser();
        //获得Xml解析器--等价上两句
        XmlPullParser pullParser = Xml.newPullParser();
        //得到一个含有xml的is输入流
         is = getAssets().open("weapon.xml");
        //设置输入流
        pullParser.setInput(is, "utf-8");
        //触发第一个事件:eventType=0 即：START_DOCUMENT
        int eventType = pullParser.getEventType();
        //没有读到文档结束之前都在while里走
        while (eventType != XmlPullParser.END_DOCUMENT) {
            switch (eventType) {//根据事件类型执行
                case XmlPullParser.START_DOCUMENT://文档开始
                    //新建对象的集合
                    mWeapons = new ArrayList<>();
                    break;
                case XmlPullParser.START_TAG://读到第一个标签时再进行switch选择
                    switch (pullParser.getName()) {//拿到标签名称
                        case "weapon"://如果标签是weapon
                            //新建一个 Weapon对象用来记录信息
                            mWeapon = new WeaponXml();
                            //获取第一个属性值
                            String material = pullParser.getAttributeValue(0);
                            //获取第二个属性值
                            String type = pullParser.getAttributeValue(1);
                            //对象装载得到的属性
                            mWeapon.setType(type);
                            mWeapon.setMaterial(material);
                            break;
                        case "name":
                            //对于没有属性的标签，可以用nextText获取标签内部的文字
                            String name = pullParser.nextText();
                            mWeapon.setName(name);
                            break;
                        case "atk":
                            Short atk = new Short(pullParser.nextText());
                            mWeapon.setAtk(atk);
                            break;
                        case "user":
                            String user = pullParser.nextText();
                            mWeapon.setUser(user);
                            break;
                    }
                    break;
                case XmlPullParser.END_TAG://当事件类型是终止标签时：即</XXX>
                    if ("weapon".equals(pullParser.getName())) {
                        mWeapons.add(mWeapon);//将生成对象加入集合，一个
                    }
                    break;
            }
            eventType = pullParser.next();//解析下一元素，更新event
        }
    } catch (Exception e) {
        e.printStackTrace();
    }finally {
        if (is != null) {
            try {
                is.close();//关流
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    return mWeapons;
}

    /**
     * 备份Xml--当然也可以备份任意的实体类作为Xml,比如短信，联系人
     */
    private void backUpXml() {
        ArrayList<WeaponXml> weapons = parseXmlWithPull();
        XmlSerializer serializer = Xml.newSerializer();
        FileOutputStream fos = null;
        try {
            String path = Environment.getExternalStorageDirectory().getAbsolutePath();
             fos = new FileOutputStream(path + File.separator + "weapon.xml");

            serializer.setOutput(fos, "utf-8");
            //文档开始
            serializer.startDocument("utf-8", true);
            serializer.startTag("", "weapons");
            for (WeaponXml weapon : weapons) {
                //新建标签： <weapon>
                serializer.startTag(null, "weapon");
                //设置属性： material="玉" type="剑"

                serializer.attribute("","material", weapon.getMaterial());
                serializer.attribute("","type", weapon.getType());
                //嵌套子标签：<name>问天剑</name>
                serializer.startTag(null, "name");
                serializer.text(weapon.getName().trim());
                serializer.endTag(null, "name");

                serializer.startTag(null, "atk");
                serializer.text(weapon.getAtk() + "");
                serializer.endTag(null, "atk");

                serializer.startTag(null, "user");
                serializer.text(weapon.getUser().trim());
                serializer.endTag(null, "user");
                //终止标签： </weapon>
                serializer.endTag(null, "weapon");
            }
            serializer.endTag("", "weapons");//标签结束
            serializer.endDocument();//文档结束
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }