java将工程目录下的文件夹压缩成zip包下载

您可以使用Java的ZipOutputStream类来压缩文件夹并生成zip文件，接着使用Java的FileInputStream类将生成的zip文件输出到response中，实现文件下载。以下是一个示例代码：

// 设置要压缩的文件夹路径
String folderPath = "path/to/folder";
// 设置生成的zip文件名
String zipFileName = "example.zip";

// 创建zip输出流
ZipOutputStream zipOut = new ZipOutputStream(new FileOutputStream(zipFileName));
// 创建缓冲输出流
BufferedOutputStream bufferedOut = new BufferedOutputStream(zipOut);

// 获取要压缩的文件夹下的所有文件
File folder = new File(folderPath);
File[] files = folder.listFiles();

// 遍历文件夹下的所有文件，将它们添加到zip输出流中
for (File file : files) {
    FileInputStream fileIn = new FileInputStream(file);
    BufferedInputStream bufferedIn = new BufferedInputStream(fileIn, 1024);
    zipOut.putNextEntry(new ZipEntry(file.getName()));
    byte[] buffer = new byte[1024];
    int readCount = 0;
    while ((readCount = bufferedIn.read(buffer)) != -1) {
        bufferedOut.write(buffer, 0, readCount);
    }
    bufferedIn.close();
}

// 关闭zip输出流和缓冲输出流
bufferedOut.flush();
bufferedOut.close();
zipOut.close();

// 将生成的zip文件输出到response中，实现文件下载
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition", "attachment; filename=\"" + zipFileName + "\"");
FileInputStream fileIn = new FileInputStream(zipFileName);
BufferedInputStream bufferedIn = new BufferedInputStream(fileIn, 1024);
byte[] buffer = new byte[1024];
int readCount = 0;
while ((readCount = bufferedIn.read(buffer)) != -1) {
    response.getOutputStream().write(buffer, 0, readCount);
}
bufferedIn.close();

请注意，上述代码中的response是HttpServletResponse对象，您需要在web环境下使用此代码。如果您是在命令行环境下运行Java程序，则需要将生成的zip文件复制到您的本地文件系统中。