一、引用

1、用XmlSerializer写xml文件与读xml文件
2、xml解析（读取xml，保存文件到xml）
3、Android-利用Document来对xml进行读取和写入操作

文内相关其他XStream解析xml数据

1、Android XStream 解析xml数据变成bean，支持CDATA
2、Retrofit 用Soap协议访问WebService 详解

二、数据格式

1、xml数据

包含单个数据，列表数据，bean数据。有tag,attribute,content-text
以下我们就是我们要读取和写入的数据

 * <?xml version='1.0' encoding='utf-8' standalone='yes' ?>
 * <xml_data>
 *      <user name="wujn" />
 *      <deviceinfos>
 *          <deviceinfo id="1">
 *               <name>仪器123</name>
 *               <price>188</price>
 *               <company>YYY</company>
 *               <usage>检测兽药残留</usage>
 *          </deviceinfo>
 *          <deviceinfo id="2">
 *               <name>仪器456</name>
 *               <price>199</price>
 *               <company>XXX</company>
 *               <usage>检测农药残留及多参数</usage>
 *          </deviceinfo>
 *      </deviceinfos>
 * </xml_data>

2、bean

public class DeviceInfo {
    String name;
    int id;
    int price;
    String company;
    String usage;

    public DeviceInfo(){}

    public DeviceInfo(String name,int id,int price,String company,String usage){
        this.name = name;
        this.id = id;
        this.price = price;
        this.company = company;
        this.usage = usage;
    }
     
   //省略get,set,tostring...
}  

三、写入

1、XmlSerializer - xml序列，本质是pull

1.1、设置输出文件流FileOutputStream，xml序列号，文本格式...
1.2、startTag和endTag为一个元素的开始和结束标志
1.3、attribute 是当前tag的属性，一般来说bean的元素都可以放在里面
1.4、text 是tag的content-text，就是文本值
1.5、关闭xml序列文本、关闭FileOutputStream

  /**写入XML数据*/
    private void WriteXmlToSdcardByXmlSerial(){
        List<DeviceInfo> deviceInfoList = new ArrayList<>();
        DeviceInfo deviceInfo = new DeviceInfo("仪器123",1,188,"YYY","检测兽药残留");
        DeviceInfo deviceInfo3 = new DeviceInfo("仪器456",2,199,"XXX","检测农药残留及多参数");
        deviceInfoList.add(deviceInfo);
        deviceInfoList.add(deviceInfo3);

        try {
            //-------内部-----------
//            // 指定流目录
//            OutputStream os = openFileOutput("persons.xml", Context.MODE_PRIVATE);
//            // 设置指定目录
//            serializer.setOutput(os, "UTF-8");

            //--------外部---------
            //xml文件的序列号器  帮助生成一个xml文件
            FileOutputStream fos = new FileOutputStream(new File(xmlPath));

            //获取到xml的序列号
            XmlSerializer serializer = Xml.newSerializer();
            //序列化初始化
            serializer.setOutput(fos, "utf-8");
            //创建xml
            serializer.startDocument("utf-8", true);

            //顶层element有且只有一个
            serializer.startTag(null,"xml_data");

            //tag+attribute:<user name="wujn" />
            //tag+text:<user>wujn</user>
            serializer.startTag(null,"user");
            serializer.attribute(null,"name","wujn");
            //serializer.text("wujn");
            serializer.endTag(null,"user");

            //多组<deviceinfo>...</deviceinfo>
            serializer.startTag(null,"deviceinfos");
            for(int i=0;i<deviceInfoList.size();i++){
                serializer.startTag(null,"deviceinfo");
                serializer.attribute(null,"id",String.valueOf(deviceInfoList.get(i).getId()));

                serializer.startTag(null,"name");
                serializer.text(deviceInfoList.get(i).getName());
                serializer.endTag(null,"name");

                serializer.startTag(null,"price");
                serializer.text(String.valueOf(deviceInfoList.get(i).getPrice()));
                serializer.endTag(null,"price");

                serializer.startTag(null,"company");
                serializer.text(deviceInfoList.get(i).getCompany());
                serializer.endTag(null,"company");

                serializer.startTag(null,"usage");
                serializer.text(deviceInfoList.get(i).getUsage());
                serializer.endTag(null,"usage");

                serializer.endTag(null,"deviceinfo");
            }
            serializer.endTag(null,"deviceinfos");

            //顶层element有且只有一个
            serializer.endTag(null,"xml_data");

            //关闭文档
            serializer.endDocument();
            //写入流关闭
            fos.flush();
            fos.close();

            ToastUtil.showShort(instance,"xml数据已导出");

        } catch (IllegalArgumentException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        } catch (IllegalStateException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        } catch (IOException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        }

    }

2、Document - dom形式

1.1、DocumentBuilderFactory工厂新建一个document
1.2、createElement 新建元素，里面放的是tag值
1.3、setAttribute 设置attribute，一般bean类数据可放这里
1.4、setTextContent 是tag的content-text，就是文本值
1.5、appendChild 添加节点元素，一层层自己控制
1.6、Transformer 把document转成String
1.7、FileOutputStream 打开，写入String.getBytes()，关闭流

/**写入XML数据*/
    private void WriteXmlToSdcardByDom(){
        List<DeviceInfo> deviceInfoList = new ArrayList<>();
        DeviceInfo deviceInfo = new DeviceInfo("仪器123",1,188,"YYY","检测兽药残留");
        DeviceInfo deviceInfo3 = new DeviceInfo("仪器456",2,199,"XXX","检测农药残留及多参数");
        deviceInfoList.add(deviceInfo);
        deviceInfoList.add(deviceInfo3);

        try {
            DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder documentBuilder = null;
            documentBuilder = documentBuilderFactory.newDocumentBuilder();
            Document document = documentBuilder.newDocument();
            document.setXmlStandalone(true);
            document.setXmlVersion("1.0");

            //根节点
            Element root = document.createElement("xml_data");
            //user节点
            Element userE = document.createElement("user");
            userE.setAttribute("name","wujn");
            root.appendChild(userE);
            //deviceinfos节点
            Element devsE = document.createElement("deviceinfos");
            for(int i=0;i<deviceInfoList.size();i++){
                //单个deviceinfo节点
                Element devE = document.createElement("deviceinfo");
                devE.setAttribute("id",String.valueOf(deviceInfoList.get(i).getId()));

                Element nameE = document.createElement("name");
                nameE.setTextContent(deviceInfoList.get(i).getName());
                devE.appendChild(nameE);

                Element priceE = document.createElement("price");
                priceE.setTextContent(String.valueOf(deviceInfoList.get(i).getPrice()));
                devE.appendChild(priceE);

                Element companyE = document.createElement("company");
                companyE.setTextContent(deviceInfoList.get(i).getCompany());
                devE.appendChild(companyE);

                Element usageE = document.createElement("usage");
                usageE.setTextContent(deviceInfoList.get(i).getUsage());
                devE.appendChild(usageE);

                //添加deviceinfo节点
                devsE.appendChild(devE);
            }
            root.appendChild(devsE);
            document.appendChild(root);


            TransformerFactory transformerFactory = TransformerFactory.newInstance();
            Transformer transformer = transformerFactory.newTransformer();

            //转成string
            transformer.setOutputProperty("encoding","utf-8");
            StringWriter stringWriter = new StringWriter();
            transformer.transform(new DOMSource(document),new StreamResult(stringWriter));
            LogUtil.i("xml stream = "+stringWriter.toString());

            //xml文件的序列号器  帮助生成一个xml文件
            FileOutputStream fos = new FileOutputStream(new File(xmlPath));
            fos.write(stringWriter.toString().getBytes());
            //写入流关闭
            fos.flush();
            fos.close();

            ToastUtil.showShort(instance,"xml数据已导出");

        } catch (IllegalArgumentException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        } catch (IllegalStateException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        } catch (IOException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        }catch (ParserConfigurationException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        }catch (TransformerConfigurationException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        }catch (TransformerException e) {
            e.printStackTrace();
            ToastUtil.showShort(instance,"xml数据导出异常："+e.getMessage());
        }

    }

四、读取

1、XmlPullParser - Pull形式，一行行解析的，减少内存消耗

1、xml解析器设置解读编码和FileInputStream
2、getEventType 获得tag标签类型，按照不同类型进行解析
XmlResourceParser.END_DOCUMENT
XmlResourceParser.START_TAG
XmlResourceParser.TEXT - 标签内文本content-text
XmlResourceParser.END_TAG
3、next() 下一行，还有nextTag,nextText等
5、数据整合
6、关闭FileInputStream流

注意：//如果xml节点确定是文本，需要检查XmlResourceParser.TEXT，防止getText() 返回 null。

/**
     * XmlPullParser - 读取XML数据
     * 逻辑上有可能有不严谨的地方
     * */
    private void ReadXmlFromSdcardByPull(){
        File xmlFile = new File(xmlPath);
        if(xmlFile.exists()){

            try {
                StringBuilder sb = new StringBuilder();
                sb.append(" -- XmlPullParser --\n");
                List<DeviceInfo> deviceInfoList = new ArrayList<>();
                DeviceInfo deviceInfo = null;
                boolean convertDeviceInfo = false;

                //文件写入流
                FileInputStream fis = new FileInputStream(xmlFile);
                //xml解析
                XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
                factory.setNamespaceAware(true);
                XmlPullParser xrp = factory.newPullParser();
                //设置input encode
                xrp.setInput(fis, "UTF-8");


                while (xrp.getEventType() != XmlResourceParser.END_DOCUMENT) {
                    if (xrp.getEventType() == XmlResourceParser.START_TAG) {
                        String tagName = xrp.getName();

                        if (tagName.equals("user")) {
                            String name = xrp.getAttributeValue(null, "name");
                            sb.append("user.name="+name+"\n");
                        }

                        else if(tagName.equals("deviceinfos")){
                            //nothing to do
                        }

                        else if(tagName.equals("deviceinfo")){
                            deviceInfo = new DeviceInfo();
                            int id = Integer.parseInt(xrp.getAttributeValue(null, "id"));
                            deviceInfo.setId(id);
                            LogUtil.d("id="+id);
                            convertDeviceInfo = true;
                        }

                        //解析 DeviceInfo
                        //<StartTag>text<EndTag> 是三个元素
                        if(convertDeviceInfo){
                            if(tagName.equals("name")) {
                                xrp.next();
                                //必须检查如果当前 xml 节点是文本，以便 getText() 不会返回 null。
                                if (xrp.getEventType() == XmlResourceParser.TEXT){
                                    String name = xrp.getText();
                                    deviceInfo.setName(name);
                                    LogUtil.d("name="+name);
                                }
                                xrp.next();

                            }

                            else if(tagName.equals("price")){
                                xrp.next();
                                if (xrp.getEventType() == XmlResourceParser.TEXT){
                                    int price = Integer.parseInt(xrp.getText());
                                    deviceInfo.setPrice(price);
                                    LogUtil.d("price="+price);
                                }
                                xrp.next();
                            }

                            else if(tagName.equals("company")){
                                xrp.next();
                                if (xrp.getEventType() == XmlResourceParser.TEXT){
                                    String company = xrp.getText();
                                    deviceInfo.setCompany(company);
                                    LogUtil.d("company="+company);
                                }
                                xrp.next();
                            }

                            else if(tagName.equals("usage")){
                                xrp.next();
                                if (xrp.getEventType() == XmlResourceParser.TEXT){
                                    String usage = xrp.getText();
                                    deviceInfo.setUsage(usage);
                                    LogUtil.d("usage="+usage);
                                }
                                xrp.next();
                            }
                        }

                    }

                    else if(xrp.getEventType() == XmlResourceParser.END_TAG){
                        String tagName = xrp.getName();
                        if(tagName.equals("deviceinfo")){
                            deviceInfoList.add(deviceInfo);
                            deviceInfo = null;
                            convertDeviceInfo = false;
                        }
                    }
                    //xrp.nextTag();
                    //xrp.nextText();
                    xrp.next();
                }

                //关闭流
                fis.close();
                fis=null;

                for (int i=0;i<deviceInfoList.size();i++){
                    sb.append(deviceInfoList.get(i).toString()+"\n");
                }

                tv_result.setText(sb.toString());

            } catch (IllegalArgumentException e) {
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            } catch (IllegalStateException e) {
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            } catch (IOException e) {
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            } catch (XmlPullParserException e) {
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            }

        }else{
            ToastUtil.showShort(instance,"xml文件不存在");
        }

    }

2、SAXParser - SAX形式

1、sax解析器设置FileInputStream 和解析助手handler
2、解析助手TestXmlHandler extends DefaultHandler
startDocument 开始文档
endDocument 结束文档
startElement 元素开始 ：localName=tag标签名，attribute元素.getValue()获取元素值
endElement 元素结束
characters 元素内content-text
3、FileInputStream 刘关闭

注意：org.apache.harmony.xml.ExpatParser$ParseException: At line 1, column 76: junk after document element 这个异常是要么解析器解析写错了，要么就是xml文档不规范，比如顶层元素有多个，规定标准是只有一个顶层元素，在这里是xml_data

/**
     * SAXParser - 读取XML数据
     * 逻辑上有可能有不严谨的地方
     *
     * org.apache.harmony.xml.ExpatParser$ParseException: At line 1, column 76: junk after document element
     * 顶层元素不止一个的异常
     * */
    private void ReadXmlFromSdcardBySAX(){
        File xmlFile = new File(xmlPath);
        if(xmlFile.exists()){
            try {
                final StringBuilder sb = new StringBuilder();
                sb.append(" -- SAXParser --\n");

                //文件写入流
                FileInputStream fis = new FileInputStream(xmlFile);

                SAXParserFactory spf = SAXParserFactory.newInstance();
                SAXParser saxParser = spf.newSAXParser();//创建解析器
                //设置解析器的相关特性，http://xnl.org/sax/features/namespaces = true;
                //表示开启命名空间特性
                //saxParser.setProperty("http://xnl.org/sax/features/namespaces", true);
                TestXmlHandler handler = new TestXmlHandler() {
                    @Override
                    void onStart() {
                        LogUtil.i("SAXParser onStart >>> ");
                    }

                    @Override
                    void onEnd(String username, List<DeviceInfo> deviceInfoList) {
                        LogUtil.i("SAXParser onEnd >>> ");

                        sb.append("user.name="+username+"\n");
                        for (int i=0;i<deviceInfoList.size();i++){
                            sb.append(deviceInfoList.get(i).toString()+"\n");
                        }

                        tv_result.setText(sb.toString());
                    }
                };
                saxParser.parse(fis, handler);

//                InputSource inputSource = new InputSource();
//                inputSource.setEncoding("utf-8");
//                inputSource.setCharacterStream(new StringReader(xmlPath));
//                saxParser.parse(new InputSource(new FileReader(new File(xmlPath))), handler);

                //关闭流
                fis.close();
                fis=null;

            }catch (IOException e){
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            }catch (SAXException e){
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            }catch (ParserConfigurationException e){
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            }

        }else{
            ToastUtil.showShort(instance,"xml文件不存在");
        }

    }


    /**
     * TestXmlHandler - SAX的解析器
     * 靠preTag也可以达到convertDeviceInfo类似的效果
     * */
    abstract class TestXmlHandler extends DefaultHandler{
        private String username = "";
        private List<DeviceInfo> deviceInfoList = new ArrayList<>();
        private DeviceInfo deviceInfo = null;
        private boolean convertDeviceInfo = true;

        private String preTag;//之前tag

        @Override
        public void startDocument() throws SAXException {
            onStart();
        }
        @Override
        public void endDocument() throws SAXException {
            onEnd(username, deviceInfoList);
        }
        abstract void onStart();
        abstract void onEnd(String username,List<DeviceInfo> deviceInfoList);

        @Override
        public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
            LogUtil.d("startElement: uri="+uri+", localName="+localName+", qName="+qName);
            preTag = localName;

            if("user".equals(localName)){
                username = attributes.getValue("name");
            }

            else if("deviceinfos".equals(localName)){
                //will be more deviceinfo
            }

            else if("deviceinfo".equals(localName)){
                deviceInfo = new DeviceInfo();
                int id = Integer.parseInt(attributes.getValue("id"));
                deviceInfo.setId(id);
                convertDeviceInfo = true;
            }
        }

        @Override
        public void endElement(String uri, String localName, String qName) throws SAXException {
            LogUtil.d("endElement: uri="+uri+", localName="+localName+", qName="+qName);
            preTag = null;

            if("deviceinfo".equals(localName)){
                deviceInfoList.add(deviceInfo);
                deviceInfo = null;
                convertDeviceInfo = false;
            }
        }

        @Override
        public void characters(char[] ch, int start, int length) throws SAXException {
            String data = new String(ch,start,length);
            LogUtil.d("characters: preTag="+preTag+", data="+data);

            if(convertDeviceInfo){
                if(preTag.equals("name")) {
                    deviceInfo.setName(data);
                    LogUtil.d("name="+data);
                }

                else if(preTag.equals("price")){
                    int price = Integer.parseInt(data);
                    deviceInfo.setPrice(price);
                    LogUtil.d("price="+price);
                }

                else if(preTag.equals("company")){
                    deviceInfo.setCompany(data);
                    LogUtil.d("company="+data);
                }

                else if(preTag.equals("usage")){
                    deviceInfo.setUsage(data);
                    LogUtil.d("usage="+data);
                }
            }
        }


    }

3、Document - dom形式：此方式需要读取整个流数据，占用内存较大，一般针对小型xml数据可以用此方法，有点在于简单易懂

1、document加载输入流
2、getElementsByTagName 获得该tag名下的所有节点
3、每个node(Element)都有获取属性，属性name和值.getAttributes().getNamedItem("name").getNodeValue()
4、每个node(Element)的文本值 content-text : getTextContent();
5、关闭输入流

/**
     * Document - 读取XML数据
     * 直观明了，但是要预加载所有数据，对xml比较大占内存比较多
     * */
    private void ReadXmlFromSdcardByDom(){
        File xmlFile = new File(xmlPath);
        if(xmlFile.exists()){
            try {
                StringBuilder sb = new StringBuilder();
                sb.append(" -- Document --\n");

                DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
                DocumentBuilder documentBuilder = null;
                documentBuilder = documentBuilderFactory.newDocumentBuilder();

                //加载输入流到document中
                //InputStream inputStream = getAssets().open("person.xml");
                FileInputStream fis = new FileInputStream(xmlFile);
                Document document = documentBuilder.parse(fis);

                NodeList userNodes = document.getElementsByTagName("user");
                for(int i=0;i<userNodes.getLength();i++){
                    sb.append("user.name="+userNodes.item(i).getAttributes().getNamedItem("name").getNodeValue()+"\n");
                }

                List<DeviceInfo> deviceInfoList = new ArrayList<>();
                DeviceInfo deviceInfo = null;
                NodeList deviceNodes = document.getElementsByTagName("deviceinfo");
                //设备节点
                for(int i=0;i<deviceNodes.getLength();i++){
                    deviceInfo = new DeviceInfo();
                    Node deviceNode = deviceNodes.item(i);
                    int id = Integer.parseInt(deviceNode.getAttributes().getNamedItem("id").getNodeValue());
                    LogUtil.d("id="+id);
                    deviceInfo.setId(id);

                    NodeList eachDeviceNodes = deviceNode.getChildNodes();
                    LogUtil.d("eachDeviceNodes.length="+eachDeviceNodes.getLength());
                    //设备下值节点
                    for(int j=0;j<eachDeviceNodes.getLength();j++){
                        String tagName = eachDeviceNodes.item(j).getNodeName();//nodename not localname
                        LogUtil.d("tagName=" + tagName);
                        String data = eachDeviceNodes.item(j).getTextContent();

                        if (tagName.equals("name")) {
                            deviceInfo.setName(data);
                            LogUtil.d("name=" + data);
                        } else if (tagName.equals("price")) {
                            int price = Integer.parseInt(data);
                            deviceInfo.setPrice(price);
                            LogUtil.d("price=" + price);
                        } else if (tagName.equals("company")) {
                            deviceInfo.setCompany(data);
                            LogUtil.d("company=" + data);
                        } else if (tagName.equals("usage")) {
                            deviceInfo.setUsage(data);
                            LogUtil.d("usage=" + data);
                        }

                    }
                    //添加设备到列表
                    deviceInfoList.add(deviceInfo);
                }

                //关闭流
                fis.close();
                fis=null;

                for (int i=0;i<deviceInfoList.size();i++){
                    sb.append(deviceInfoList.get(i).toString()+"\n");
                }

                tv_result.setText(sb.toString());

            }catch (IOException e){
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            }catch (ParserConfigurationException e){
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            }catch (SAXException e){
                e.printStackTrace();
                ToastUtil.showShort(instance,"xml数据导入异常："+e.getMessage());
            }
        }else{
            ToastUtil.showShort(instance,"xml文件不存在");
        }
    }

五、读取和写入文本

/**
     * 从file文件中读取string来
     * */
    public static String readFromFile(String fPath) throws IOException{
        BufferedReader bf = new BufferedReader(new FileReader(fPath));

        String content = "";
        StringBuilder sb = new StringBuilder();

        while (content != null) {
            content = bf.readLine();
            if (content == null) {
                break;
            }
            sb.append(content.trim());
        }
        bf.close();

        return sb.toString();
    }

    /**
     * 写string到file文件中
     * */
    public static void writeToFile(String content,String fPath)throws IOException{
        File txt = new File(fPath);
        if (!txt.exists()) {
            txt.createNewFile();
        }

        FileOutputStream fos = new FileOutputStream(txt);
        fos.write(content.getBytes());
        fos.flush();
        fos.close();
    }