Android数据解析之XML篇

假设在网络上有这么一段数据XML数据

<apps>
<app>
<id>1</id>
<name>Google Maps</name>
<version>1.0</version>
</app>
<app>
<id>2</id>
<name>Chrome</name>
<version>2.1</version>
</app>
<app>
<id>3</id>
<name>Google Play</name>
<version>2.3</version>
</app>
</apps>

Pull解析（这里我们将通过网络传输回的数据以String类型传入函数进行解析）

private void parseXMLWithPull(String xmlData) {
    try {
        //获取一个XmlPullParserFactory的实例
        XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
        XmlPullParser xmlPullParser = factory.newPullParser();
        xmlPullParser.setInput(new StringReader(xmlData));
        //getEventType用于获取当前解析事件
        int eventType = xmlPullParser.getEventType();
        String id = "";
        String name = "";
        String version = "";
        //判断解析是否完成
        while (eventType != XmlPullParser.END_DOCUMENT) {
            String nodeName = xmlPullParser.getName();
            switch (eventType) {
                // 开始解析某个结点
                case XmlPullParser.START_TAG: {
                    if ("id".equals(nodeName)) {
                        id = xmlPullParser.nextText();
                    } else if ("name".equals(nodeName)) {
                        name = xmlPullParser.nextText();
                    } else if ("version".equals(nodeName)) {
                        version = xmlPullParser.nextText();
                    }
                    break;
                }

                // 完成解析某个结点
                case XmlPullParser.END_TAG: {
                    if ("app".equals(nodeName)) {
                        Log.d("MainActivity", "id is " + id);
                        Log.d("MainActivity", "name is " + name);
                        Log.d("MainActivity", "version is " + version);
                    }
                    break;
                }
                default:
                    break;
            }
            eventType = xmlPullParser.next();
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

SAX解析

新建一个类继承自 DefaultHandler，并重写父类的五个方法

public class SAXHandler extends DefaultHandler {
    @Override
    public void startDocument() throws SAXException {//开始解析xml
    }
    @Override
    public void startElement(String uri, String localName, String qName,
                             Attributes attributes) throws SAXException {//开始解析某个节点
    }
    @Override
    public void characters(char[] ch, int start, int length) throws
            SAXException {//获取节点内容
    }
    @Override
    public void endElement(String uri, String localName, String qName) throws
            SAXException {//结束解析
    }
    @Override
    public void endDocument() throws SAXException {
    }
}

针对本文XML数据的解析

public class SAXHandler extends DefaultHandler {
    private String nodeName;
    private StringBuilder id;
    private StringBuilder name;
    private StringBuilder version;

    @Override
    public void startDocument() throws SAXException {
        id = new StringBuilder();
        name = new StringBuilder();
        version = new StringBuilder();
    }

    @Override
    public void startElement(String uri, String localName, String qName,
                             Attributes attributes) throws SAXException {
        // 记录当前结点名
        nodeName = localName;
    }

    @Override
    public void characters(char[] ch, int start, int length) throws
            SAXException {
        // 根据当前的结点名判断将内容添加到哪一个StringBuilder对象中
        if ("id".equals(nodeName)) {
            id.append(ch, start, length);
        } else if ("name".equals(nodeName)) {
            name.append(ch, start, length);
        } else if ("version".equals(nodeName)) {
            version.append(ch, start, length);
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws
            SAXException {
        if ("app".equals(localName)) {
            Log.d("ContentHandler", "id is " + id.toString().trim());
            Log.d("ContentHandler", "name is " + name.toString().trim());
            Log.d("ContentHandler", "version is " + version.toString().trim());
            //清空StringBuilder,上面的trim()用于去除多余的换行空格
            id.setLength(0);
            name.setLength(0);
            version.setLength(0);
        }
    }

    @Override
    public void endDocument() throws SAXException {
    }
}

OK,简单的xml解析就是这些了，接下来再重点总结一下gson格式的数据解析。