以下是Java代码实现将zip文件分卷压缩的功能：

以下是Java代码实现将zip文件分卷压缩的功能：

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

public class ZipSplitter {
    private static final int BUFFER_SIZE = 4096;

    public static void split(String zipFile, int splitSize) throws IOException {
        File file = new File(zipFile);
        if (!file.exists()) {
            throw new FileNotFoundException("File not found: " + zipFile);
        }

        if (splitSize <= 0) {
            throw new IllegalArgumentException("Split size must be positive: " + splitSize);
        }

        byte[] buffer = new byte[BUFFER_SIZE];
        ZipInputStream zis = new ZipInputStream(new FileInputStream(file));
        ZipEntry entry = zis.getNextEntry();
        int size = 0;
        int part = 1;

        while (entry != null) {
            String fileName = entry.getName();
            long entrySize = entry.getSize();
            if (entrySize < 0) {
                throw new IOException("Entry size is unknown: " + fileName);
            }

            File outputFile = new File(fileName);
            FileOutputStream fos = new FileOutputStream(outputFile);
            BufferedOutputStream bos = new BufferedOutputStream(fos, BUFFER_SIZE);

            int count;
            long total = 0;
            while ((count = zis.read(buffer, 0, BUFFER_SIZE)) != -1) {
                bos.write(buffer, 0, count);
                total += count;
                if (total >= splitSize) {
                    bos.flush();
                    bos.close();

                    String outputZip = String.format("%s.%03d", zipFile, part);
                    ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(outputZip));
                    zos.putNextEntry(new ZipEntry(fileName));

                    FileInputStream fis = new FileInputStream(outputFile);
                    BufferedInputStream bis = new BufferedInputStream(fis, BUFFER_SIZE);

                    while ((count = bis.read(buffer, 0, BUFFER_SIZE)) != -1) {
                        zos.write(buffer, 0, count);
                    }

                    bis.close();
                    zos.close();
                    outputFile.delete();

                    part++;
                    size = 0;
                    break;
                }
            }

            bos.flush();
            bos.close();

            if (total < splitSize) {
                size += total;
            }

            entry = zis.getNextEntry();
        }

        zis.close();

        if (size > 0) {
            String outputZip = String.format("%s.%03d", zipFile, part);
            ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(outputZip));
            zos.putNextEntry(new ZipEntry("dummy"));

            FileInputStream fis = new FileInputStream(new File("dummy"));
            BufferedInputStream bis = new BufferedInputStream(fis, BUFFER_SIZE);

            int count;
            while ((count = bis.read(buffer, 0, BUFFER_SIZE)) != -1) {
                zos.write(buffer, 0, count);
            }

            bis.close();
            zos.close();
        }
    }

    public static void main(String[] args) throws IOException {
        String zipFile = "example.zip";
        int splitSize = 1024 * 1024; // split into 1MB parts
        split(zipFile, splitSize);
    }
}

这段代码的实现思路是，遍历zip文件中的每个entry，读取其内容并将其写入一个临时文件中，累加已写入的字节数，当累加数达到指定的分卷大小时，将临时文件压缩成一个新的zip文件，并从累加数计数器和临时文件中删除已经压缩的数据。如果遍历完所有entry后还有未压缩的数据，将其写入一个虚拟的entry中并压缩成最后一个分卷。