単一ディレクトリをZIP形式で圧縮

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

デスクトップ上の単一ディレクトリを圧縮し、デスクトップ上にZIPファイルを作成する。

String zipPathString = System.getProperty("user.home") + File.separator + "Desktop" + File.separator + "sample.zip";

try (ZipOutputStream zipOutputStream = new ZipOutputStream(new FileOutputStream(zipPathString))) {
    Path targetPath = Paths.get(System.getProperty("user.home") + File.separator + "Desktop" + File.separator + "sample");
    compressDirectory(targetPath, targetPath.getFileName().toString(), zipOutputStream);
} catch (FileNotFoundException e) {
    System.out.println("ディレクトリの圧縮中にエラーが発生しました！ (" + e.getMessage() + ")");
} catch (IOException e) {
    System.out.println("ディレクトリの圧縮中にエラーが発生しました！ (" + e.getMessage() + ")");
}

ディレクトリの圧縮（ZIP形式）メソッド

void compressDirectory(Path targetPath, String parentDirectoryName, ZipOutputStream zipOutputStream) { 
    try (DirectoryStream<Path> directoryStreamPath = Files.newDirectoryStream(targetPath)) {
        String entryDirectoryName;
        ZipEntry zipEntry;
        int bytes;
        byte[] dataBuffer = new byte[16384];

        for (Path path : directoryStreamPath) {
            if (Files.isDirectory(path)) {
                entryDirectoryName = parentDirectoryName + "/" + path.getFileName().toString() + "/";  // ZIPエントリ名には必ず「/」を使う
                zipOutputStream.putNextEntry(new ZipEntry(entryDirectoryName));
                zipOutputStream.closeEntry();
                compressDirectory(path, parentDirectoryName + "/" + path.getFileName().toString(), zipOutputStream);
            } else {
                zipEntry = new ZipEntry(parentDirectoryName + "/" + path.getFileName().toString());
                zipOutputStream.putNextEntry(zipEntry);
 
                try (InputStream inputStream = Files.newInputStream(path);
                     BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream)) {
                    while ((bytes = bufferedInputStream.read(dataBuffer, 0, dataBuffer.length)) != -1) {
                        zipOutputStream.write(dataBuffer, 0, bytes);
                    }
                }
 
                zipOutputStream.closeEntry();
            }
        }
    } catch (IOException e) {
        System.out.println("ディレクトリの圧縮中にエラーが発生しました！ (" + e.getMessage() + ")");
    }
}