TodofukenAndShiKuChoSonCode.java

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.Collection;
import java.util.List;
import java.util.function.Predicate;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Stream;

import org.apache.commons.collections4.IterableUtils;
import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.WorkbookFactory;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Element;
import org.jsoup.nodes.Node;
import org.jsoup.select.Elements;

import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.mariten.kanatools.KanaConverter;

public class TodofukenAndShiKuChoSonCode {

	private static class KanjiHiraganaKatakana {

		private String kanji, hiragana, katakana;
	}

	private static class Denshijiti {

		private String sheetName, dantaiCode;

		private Boolean todofuken;

		private KanjiHiraganaKatakana todofukenName, shiKuChoSonName;

	}

	public static void main(final String[] args) throws IOException {
		//
		List<Element> es = toList(
				filter(stream(select(Jsoup.parse(new URL("https://www.soumu.go.jp/denshijiti/code.html"), 0), "li")),
						x -> StringUtils.startsWith(x.text(), "「都道府県コード及び市区町村コード」")));
		//
		try (final InputStream is = new URL(absUrl(IterableUtils.size(
				(es = toList(filter(stream(select(IterableUtils.size(es) > 0 ? IterableUtils.get(es, 0) : null, "* a")),
						x -> StringUtils.endsWith(x.attr("href"), ".xls"))))) == 1 ? IterableUtils.get(es, 0) : null,
				"href")).openStream(); final Workbook wb = WorkbookFactory.create(is)) {
			//
			if (wb != null && wb.iterator() != null) {
				//
				Denshijiti item = null;
				//
				int columnIndex;
				//
				Matcher matcher = null;
				//
				File file = null;
				//
				for (final Sheet sheet : wb) {
					//
					if (sheet == null || sheet.iterator() == null) {
						//
						continue;
						//
					} // if
						//
					for (final Row row : sheet) {
						//
						if (row == null || row.iterator() == null) {
							//
							continue;
							//
						} // if
							//
						for (final Cell cell : row) {
							//
							if (cell == null) {
								//
								break;
								//
							} // if
								//
							if ((columnIndex = cell.getColumnIndex()) == 0) {
								//
								if ((matcher = Pattern.compile("^(\\d{6})(.\\d)?$").matcher(toString(cell))) == null
										|| !matcher.matches() || matcher.groupCount() < 1) {
									//
									item = null;
									//
									break;
									//
								} // if
									//
								(item = new Denshijiti()).sheetName = sheet.getSheetName();
								//
								item.dantaiCode = matcher.group(0);
								//
							} else if ((columnIndex = cell.getColumnIndex()) == 1) {
								//
								(item.todofukenName = new KanjiHiraganaKatakana()).kanji = toString(cell);
								//
							} else if (columnIndex == 2) {
								//
								(item.shiKuChoSonName = new KanjiHiraganaKatakana()).kanji = toString(cell);
								//
							} else if (columnIndex == 3 && item.todofukenName != null) {
								//
								item.todofukenName.hiragana = KanaConverter.convertKana(
										item.todofukenName.katakana = toString(cell),
										KanaConverter.OP_HAN_KATA_TO_ZEN_HIRA);
								//
							} else if (columnIndex == 4 && item.shiKuChoSonName != null) {
								//
								item.shiKuChoSonName.hiragana = KanaConverter.convertKana(
										item.shiKuChoSonName.katakana = toString(cell),
										KanaConverter.OP_HAN_KATA_TO_ZEN_HIRA);
								//
							} // if
								//
						} // for
							//
						if (item == null) {
							//
							continue;
							//
						} // if
							//
						if (item.shiKuChoSonName != null) {
							//
							item.todofuken = StringUtils.isBlank(item.shiKuChoSonName.katakana);
							//
						} // if
							//
						if (file == null) {
							//
							file = new File("Denshijita.txt");
							//
							FileUtils.writeStringToFile(file, "", StandardCharsets.UTF_8);
							//
						} // if
							//
						FileUtils.writeStringToFile(file,
								StringUtils.join(StringUtils.joinWith(",", StringUtils.join(row, ","),
										new ObjectMapper().setVisibility(PropertyAccessor.ALL, Visibility.ANY)
												.writeValueAsString(item)),
										System.lineSeparator()),
								StandardCharsets.UTF_8, true);
						//
					} // for
						//
				} // for
					//
				System.out.println(file != null ? file.getAbsolutePath() : null);
				//
			} // if
				//
		} // try
			//
	}

	private static String absUrl(final Node instance, final String attributeKey) {
		return instance != null ? instance.absUrl(attributeKey) : null;
	}

	private static String toString(final Object instance) {
		return instance != null ? instance.toString() : null;
	}

	private static <T> List<T> toList(final Stream<T> instance) {
		return instance != null ? instance.toList() : null;
	}

	private static <T> Stream<T> filter(final Stream<T> instance, final Predicate<? super T> predicate) {
		return instance != null ? instance.filter(predicate) : null;
	}

	private static <E> Stream<E> stream(final Collection<E> instance) {
		return instance != null ? instance.stream() : null;
	}

	private static Elements select(final Element instance, final String cssQuery) {
		return instance != null ? instance.select(cssQuery) : null;
	}

}

Required dependencies

<!--https://mvnrepository.com/artifact/org.jsoup/jsoup-->
<dependency>
	<groupId>org.jsoup</groupId>
	<artifactId>jsoup</artifactId>
	<version>1.17.2</version>
</dependency>
<!--https://mvnrepository.com/artifact/org.apache.commons/commons-lang3-->
<dependency>
	<groupId>org.apache.commons</groupId>
	<artifactId>commons-lang3</artifactId>
	<version>3.14.0</version>
</dependency>
<!--https://mvnrepository.com/artifact/org.apache.poi/poi -->
<dependency>
	<groupId>org.apache.poi</groupId>
	<artifactId>poi</artifactId>
	<version>5.2.5</version>
</dependency>
<!--https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind-->
<dependency>
	<groupId>com.fasterxml.jackson.core</groupId>
	<artifactId>jackson-databind</artifactId>
	<version>2.17.0</version>
</dependency>
<!--https://mvnrepository.com/artifact/com.mariten/kanatools-->
<dependency>
	<groupId>com.mariten</groupId>
	<artifactId>kanatools</artifactId>
	<version>1.3.0</version>
</dependency>

都道府県

010006,北海道,,ﾎｯｶｲﾄﾞｳ,,{"sheetName":"R6.1.1現在の団体","dantaiCode":"010006","todofuken":true,"todofukenName":{"kanji":"北海道","hiragana":"ほっかいどう","katakana":"ﾎｯｶｲﾄﾞｳ"},"shiKuChoSonName":{"kanji":"","hiragana":"","katakana":""}}

市区町村

011002,北海道,札幌市,ﾎｯｶｲﾄﾞｳ,ｻｯﾎﾟﾛｼ,{"sheetName":"R6.1.1現在の団体","dantaiCode":"011002","todofuken":false,"todofukenName":{"kanji":"北海道","hiragana":"ほっかいどう","katakana":"ﾎｯｶｲﾄﾞｳ"},"shiKuChoSonName":{"kanji":"札幌市","hiragana":"さっぽろし","katakana":"ｻｯﾎﾟﾛｼ"}}