SAX解析及修改xml

分手后的思念是犯贱 2022-12-13 01:58 195阅读 0赞

修改xml，通常不会全篇修改，只修改某些关键节点

## 解析 ##

用到的实体类

public class RadarSetEntity {
        
        private String signSpeed;
        private String speedLimit;
        private String bigCarSignSpeed;
        private String bigCarSpeedLimit;
        private String radarConstantCorrection;
    
        public String getRadarConstantCorrection() {
        
            return radarConstantCorrection;
        }
    
        public void setRadarConstantCorrection(String radarConstantCorrection) {
        
            this.radarConstantCorrection = radarConstantCorrection;
        }
    
        public String getSignSpeed() {
        
            return signSpeed;
        }
    
        public void setSignSpeed(String signSpeed) {
        
            this.signSpeed = signSpeed;
        }
    
        public String getSpeedLimit() {
        
            return speedLimit;
        }
    
        public void setSpeedLimit(String speedLimit) {
        
            this.speedLimit = speedLimit;
        }
    
        public String getBigCarSignSpeed() {
        
            return bigCarSignSpeed;
        }
    
        public void setBigCarSignSpeed(String bigCarSignSpeed) {
        
            this.bigCarSignSpeed = bigCarSignSpeed;
        }
    
        public String getBigCarSpeedLimit() {
        
            return bigCarSpeedLimit;
        }
    
        public void setBigCarSpeedLimit(String bigCarSpeedLimit) {
        
            this.bigCarSpeedLimit = bigCarSpeedLimit;
        }
    }

获取解析文件

private static RadarSetEntity requestRadarData() {
        
            File file = new File(SetRadarFragment.radar_path);
            if (file.exists()) {
        
                return XmlUtils.readRadarSetEntityBySax(file);
            } else {
        
                L.e("文件为空");
            }
            return null;
        }

发起解析

public static RadarSetEntity readRadarSetEntityBySax(File file) {
        
            try {
        
                SAXParserFactory spf = SAXParserFactory.newInstance();
                SAXParser saxParser = spf.newSAXParser();
                RadarGetHandler handler = new RadarGetHandler();
                saxParser.parse(file, handler);
                return handler.getRadarSetEntity();
            } catch (Exception e) {
        
                e.printStackTrace();
            }
            return null;
        }

解析过程

package com.ahsoft.tachymeterapp.utils.xml;
    
    import com.ahsoft.tachymeterapp.model.entity.RadarSetEntity;
    
    import org.xml.sax.Attributes;
    import org.xml.sax.helpers.DefaultHandler;
    
    /**
     * created by Taoyuan on 2020/9/4
     * RadarSet xml 内容处理
     */
    public class RadarGetHandler extends DefaultHandler {
        
    
        private String tagName = null;//当前解析的元素标签
        private RadarSetEntity radarSet;
        private int laneId = 0;
    
        RadarSetEntity getRadarSetEntity() {
        
            return radarSet;
        }
    
    
        /**
         * 文档开始
         **/
        @Override
        public void startDocument() {
        
            radarSet = new RadarSetEntity();
        }
    
    
        /**
         * 标签开始
         *
         * @param uri        命名空间
         * @param localName  元素本地名称（不带前缀）
         * @param qName      元素的限定名（带前缀）
         * @param attributes 元素属性
         */
        @Override
        public void startElement(String uri, String localName, String qName, Attributes attributes) {
        
            this.tagName = localName;
        }
    
        /**
         * 接收标签中的字符数据
         *
         * @param ch     存放标签中的内容
         * @param start  起始位置
         * @param length 内容长度
         */
        @Override
        public void characters(char[] ch, int start, int length) {
        
            if (tagName != null) {
        
                String value = new String(ch, start, length);
                switch (tagName) {
        
                    case "laneId": // 车道标识
                        laneId = Integer.parseInt(value);
                        break;
                    case "signSpeed": // 30
                        if (laneId == 1) {
        
                            radarSet.setSignSpeed(value);
                        }
                        break;
                    case "speedLimit": // 33
                        if (laneId == 1) {
        
                            radarSet.setSpeedLimit(value);
                        }
                        break;
                    case "bigCarSignSpeed":// 30
                        if (laneId == 1) {
        
                            radarSet.setBigCarSignSpeed(value);
                        }
                        break;
                    case "bigCarSpeedLimit":// 33
                        if (laneId == 1) {
        
                            radarSet.setBigCarSpeedLimit(value);
                        }
                        break;
                    case "radarConstantCorrection":// 雷达常量校正系数
                        if (laneId == 1) {
        
                            radarSet.setRadarConstantCorrection(value);
                        }
                        break;
                }
            }
        }
    
    
        /**
         * 标签结束
         *
         * @param uri       命名空间
         * @param localName 元素本地名称（不带前缀）
         * @param qName     元素的限定名（带前缀）
         */
        @Override
        public void endElement(String uri, String localName, String qName) {
        
            this.tagName = null;
        }
    
    
    }

## 修改 ##

发起解析

public static File writeRadarSetEntityBySax(File file, RadarSetEntity radarSetEntity) {
        
            try {
        
                SAXParserFactory spf = SAXParserFactory.newInstance();
                SAXParser saxParser = spf.newSAXParser();
                RadarSetHandler handler = new RadarSetHandler(radarSetEntity);
                saxParser.parse(file, handler);
                return handler.getFile();
            } catch (Exception e) {
        
                e.printStackTrace();
            }
            return null;
        }

解析过程

package com.ahsoft.tachymeterapp.utils.xml;
    
    import com.ahsoft.tachymeterapp.model.entity.RadarSetEntity;
    import com.ahsoft.tachymeterapp.view.fragment.SetRadarFragment;
    import com.jty.myutils.utils.FileUtils;
    
    import org.xml.sax.Attributes;
    import org.xml.sax.SAXException;
    import org.xml.sax.helpers.DefaultHandler;
    
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.IOException;
    
    import javax.xml.transform.OutputKeys;
    import javax.xml.transform.Transformer;
    import javax.xml.transform.TransformerConfigurationException;
    import javax.xml.transform.sax.SAXTransformerFactory;
    import javax.xml.transform.sax.TransformerHandler;
    import javax.xml.transform.stream.StreamResult;
    
    /**
     * created by Taoyuan on 2020/9/30
     * RadarSet xml 内容处理
     */
    public class RadarSetHandler extends DefaultHandler {
        
    
        private String tagName = null;//当前解析的元素标签
        private TransformerHandler writeHandler; // 写文档
        private File file; //要写出的文件
        private RadarSetEntity radarSet; // 要变更的实体类
        private int laneId = 0;
    
        public RadarSetHandler(RadarSetEntity radarSetEntity) {
        
            file = new File(SetRadarFragment.radar_put_path);
            FileUtils.createOrExistsFile(file);
            radarSet = radarSetEntity;
        }
    
        /**
         * 返回写完的文件
         *
         * @return 写完的文件
         */
        public File getFile() {
        
            return file;
        }
    
        /**
         * 文档开始
         **/
        @Override
        public void startDocument() throws SAXException {
        
            // prepare
            SAXTransformerFactory transformerFactory = (SAXTransformerFactory) SAXTransformerFactory.newInstance();
            try {
        
                this.writeHandler = transformerFactory.newTransformerHandler();
                Transformer transformer = writeHandler.getTransformer();
                transformer.setOutputProperty(OutputKeys.ENCODING, "utf-8");
                transformer.setOutputProperty(OutputKeys.INDENT, "yes");
    
                StreamResult streamResult = new StreamResult(new FileOutputStream(file));
                this.writeHandler.setResult(streamResult);
            } catch (IOException | TransformerConfigurationException e) {
        
                e.printStackTrace();
            }
    
            // begin
            this.writeHandler.startDocument();
        }
    
    
        /**
         * 标签开始
         *
         * @param uri        命名空间
         * @param localName  元素本地名称（不带前缀）
         * @param qName      元素的限定名（带前缀）
         * @param attributes 元素属性
         */
        @Override
        public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        
            this.tagName = localName;
            this.writeHandler.startElement(uri, localName, qName, attributes);
        }
    
        /**
         * 接收标签中的字符数据
         *
         * @param ch     存放标签中的内容
         * @param start  起始位置
         * @param length 内容长度
         */
        @Override
        public void characters(char[] ch, int start, int length) throws SAXException {
        
            if (tagName != null) {
        
                char[] ch2 = null;
                String all = new String(ch, 0, ch.length);
                StringBuilder sb = new StringBuilder();
                String value = new String(ch, start, length);
                switch (tagName) {
        
                    case "laneId": //车道标识
                        laneId = Integer.parseInt(value);
                        break;
                    case "signSpeed": // 30
                        if (laneId == 1) {
        
                            sb.append(all.substring(0, start).concat(radarSet.getSignSpeed()));
                            ch2 = sb.toString().toCharArray();
                        }
                        break;
                    case "speedLimit": // 33
                        if (laneId == 1) {
        
                            sb.append(all.substring(0, start).concat(radarSet.getSpeedLimit()));
                            ch2 = sb.toString().toCharArray();
                        }
                        break;
                    case "bigCarSignSpeed":// 30
                        if (laneId == 1) {
        
                            sb.append(all.substring(0, start).concat(radarSet.getBigCarSignSpeed()));
                            ch2 = sb.toString().toCharArray();
                        }
                        break;
                    case "bigCarSpeedLimit":// 33
                        if (laneId == 1) {
        
                            sb.append(all.substring(0, start).concat(radarSet.getBigCarSpeedLimit()));
                            ch2 = sb.toString().toCharArray();
                        }
                        break;
                    case "radarConstantCorrection":// 雷达常量校正系数
                        if (laneId == 1) {
        
                            sb.append(all.substring(0, start).concat(radarSet.getRadarConstantCorrection()));
                            ch2 = sb.toString().toCharArray();
                        }
                        break;
                }
    
                if (ch2 != null) {
        
                    this.writeHandler.characters(ch2, start, length);
                } else {
        
                    this.writeHandler.characters(ch, start, length);
                }
            }
        }
    
    
        /**
         * 标签结束
         *
         * @param uri       命名空间
         * @param localName 元素本地名称（不带前缀）
         * @param qName     元素的限定名（带前缀）
         */
        @Override
        public void endElement(String uri, String localName, String qName) throws SAXException {
        
            this.tagName = null;
            this.writeHandler.endElement(uri, localName, qName);
        }
    
        /**
         * 文档结束
         **/
        @Override
        public void endDocument() throws SAXException {
        
            this.writeHandler.endDocument();
        }
    
    
    }