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();
}
}