如果你是一个java高级工程师，现在要你用java代码实现一个业务场景，要求对大小为50G往上的文件目录进行加密压缩，压缩为zip文件，效率越快越好，并实现zip加密压缩文件的解压方法,把java代码的具体实现出来并用中文注释

好的，下面是用Java实现该业务场景的代码：

import java.io.*;
import java.util.zip.*;

public class ZipUtil {
    private static final int BUFFER_SIZE = 1024;

    /**
     * 将指定目录下的文件压缩成zip文件
     * @param srcDirPath 压缩文件夹路径
     * @param zipFilePath 压缩后文件夹路径
     * @param password 压缩密码，若不需要密码可传null
     */
    public static void zip(String srcDirPath, String zipFilePath, String password) {
        File srcDir = new File(srcDirPath);
        if (!srcDir.exists()) {
            throw new RuntimeException("Source directory does not exist: " + srcDirPath);
        }

        File zipFile = new File(zipFilePath);
        if (zipFile.exists()) {
            throw new RuntimeException("Target file already exists: " + zipFilePath);
        }

        ZipOutputStream zos = null;
        try {
            zos = new ZipOutputStream(new FileOutputStream(zipFile));
            if (password != null) {
                // 设置压缩密码
                zos.setMethod(ZipOutputStream.DEFLATED);
                zos.setEncryption(ZipOutputStream.STANDARD_ENCRYPTION, password.getBytes());
            }

            // 递归压缩文件夹
            compress(srcDir, "", zos);
        } catch (IOException e) {
            throw new RuntimeException("Failed to compress directory: " + srcDirPath, e);
        } finally {
            if (zos != null) {
                try {
                    zos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 递归压缩文件夹
     * @param file 当前压缩文件对象
     * @param parentPath 父级文件夹路径
     * @param zos 压缩流
     */
    private static void compress(File file, String parentPath, ZipOutputStream zos) throws IOException {
        if (file.isDirectory()) {
            // 如果是文件夹，则递归压缩其下面的文件
            File[] files = file.listFiles();
            for (File subFile : files) {
                compress(subFile, parentPath + file.getName() + File.separator, zos);
            }
        } else {
            // 如果是文件，则压缩该文件
            BufferedInputStream bis = null;
            try {
                bis = new BufferedInputStream(new FileInputStream(file));
                ZipEntry entry = new ZipEntry(parentPath + file.getName());
                zos.putNextEntry(entry);
                int len;
                byte[] data = new byte[BUFFER_SIZE];
                while ((len = bis.read(data, 0, BUFFER_SIZE)) != -1) {
                    zos.write(data, 0, len);
                }
                zos.closeEntry();
            } finally {
                if (bis != null) {
                    try {
                        bis.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

    /**
     * 解压zip文件
     * @param zipFilePath zip文件路径
     * @param destDirPath 解压后文件夹路径
     * @param password 解压密码，若无密码可传null
     */
    public static void unzip(String zipFilePath, String destDirPath, String password) {
        File zipFile = new File(zipFilePath);
        if (!zipFile.exists()) {
            throw new RuntimeException("Zip file does not exist: " + zipFilePath);
        }

        File destDir = new File(destDirPath);
        if (!destDir.exists()) {
            destDir.mkdirs();
        }

        ZipInputStream zis = null;
        try {
            zis = new ZipInputStream(new FileInputStream(zipFile));
            if (password != null) {
                // 设置解压密码
                zis.setPassword(password.getBytes());
            }

            ZipEntry entry = null;
            while ((entry = zis.getNextEntry()) != null) {
                String entryName = entry.getName();
                String fileName = destDirPath + File.separator + entryName;
                File file = new File(fileName);
                if (entry.isDirectory()) {
                    file.mkdirs();
                } else {
                    // 如果是文件，则解压该文件
                    FileOutputStream fos = null;
                    try {
                        fos = new FileOutputStream(file);
                        int len;
                        byte[] data = new byte[BUFFER_SIZE];
                        while ((len = zis.read(data, 0, BUFFER_SIZE)) != -1) {
                            fos.write(data, 0, len);
                        }
                    } finally {
                        if (fos != null) {
                            try {
                                fos.close();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
                zis.closeEntry();
            }
        } catch (IOException e) {
            throw new RuntimeException("Failed to unzip file: " + zipFilePath, e);
        } finally {
            if (zis != null) {
                try {
                    zis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

其中，`zip`方法实现了对指定目录下的文件进行压缩，可指定压缩密码；`unzip`方法实现了对zip文件进行解压，可指定解压密码。注释已在代码中标明。