com.gabrielittner.threetenbp.ZoneWriter Maven / Gradle / Ivy

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Lazy loading ZoneRuleProvider for ThreeTenBp

There is a newer version: 0.9.0

package com.gabrielittner.threetenbp;

import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.FileVisitor;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Map;
import java.util.SortedMap;
import org.threeten.bp.zone.ZoneRules;
import org.threeten.bp.zone.ZoneRulesCompat;

final class ZoneWriter {

    private final Path outputDir;

    ZoneWriter(Path outputDir) {
        this.outputDir = outputDir;
    }

    void writeZones(SortedMap zones) throws IOException {
        if (Files.exists(outputDir)) {
            Files.walkFileTree(outputDir, FILE_DELETER);
        }
        for (Map.Entry entry : zones.entrySet()) {
            writeZoneRulesFile(outputDir.resolve(fileName(entry.getKey())), entry.getValue());
        }
    }

    private void writeZoneRulesFile(Path path, ZoneRules rules) throws IOException {
        Files.deleteIfExists(path);
        if (!Files.exists(path.getParent())) {
            Files.createDirectories(path.getParent());
        }
        Files.createFile(path);
        try (DataOutputStream out = new DataOutputStream(Files.newOutputStream(path))) {
            out.writeByte(1);
            out.writeUTF("TZDB-ZONE");
            ZoneRulesCompat.writeZoneRules(rules, out);
        }
    }

    static String fileName(String zoneId) {
        return "tzdb/" + zoneId + ".dat";
    }

    private final FileVisitor FILE_DELETER = new SimpleFileVisitor() {
            @Override
            public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                Files.delete(file);
                return FileVisitResult.CONTINUE;
            }

            @Override
            public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
                Files.delete(dir);
                return FileVisitResult.CONTINUE;
            }
        };
}