优化代码@PostMapping("/downInvoices4") public void downInvoices4(@RequestBody List<String> pathList,HttpServletResponse response) { String UUIDStr = String.valueOf(UUID.randomUUID()); String folderName = "invoice" + UUIDStr.replace("-",""); response.setContentType("application/octet-stream"); response.setHeader("Content-Disposition", "attachment;filename="+folderName+".zip"); try { URL url = new URL(pathList.get(0)); URLConnection coon = url.openConnection(); InputStream is = coon.getInputStream(); ServletOutputStream sos = response.getOutputStream(); ZipInputStream zis = new ZipInputStream(is); ZipEntry zipEntry =zis.getNextEntry(); ZipOutputStream zos = new ZipOutputStream(sos); zos.putNextEntry(zipEntry); zos.closeEntry(); IoUtils.copy(zis,zos); zos.close(); zis.close(); sos.close(); is.close(); } catch (Exception e) { throw new RuntimeException(e); } }

这段代码可以进行一些优化：

1. 首先，建议将该方法的返回类型改为 ResponseEntity<byte[]>，这样可以更好地控制响应的内容。同时，也可以避免一些潜在的问题，比如下载文件时可能会出现乱码的情况。

2. 接着，可以将生成文件名和设置响应头的代码提取出来，作为一个单独的方法。这样可以提高代码的可读性和复用性。

3. 然后，可以使用 try-with-resources 语句来自动关闭流，避免出现资源泄漏的情况。

4. 最后，建议对输入参数进行必要的校验，比如判断 pathList 是否为空，以及其中是否包含有效的 URL。

下面是优化后的代码示例：

@PostMapping("/downInvoices4")
public ResponseEntity<byte[]> downInvoices4(@RequestBody List<String> pathList) {
    validate(pathList); // 校验输入参数
    
    try {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ZipOutputStream zos = new ZipOutputStream(baos);

        for (String path : pathList) {
            URL url = new URL(path);
            URLConnection conn = url.openConnection();
            InputStream is = conn.getInputStream();
            ZipEntry entry = new ZipEntry(getFileName(path));
            zos.putNextEntry(entry);
            IoUtils.copy(is, zos);
            zos.closeEntry();
            is.close();
        }

        zos.close();

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        headers.setContentDisposition(ContentDisposition.attachment().filename(getZipFileName()).build());

        return new ResponseEntity<>(baos.toByteArray(), headers, HttpStatus.OK);
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}

private void validate(List<String> pathList) {
    if (pathList == null || pathList.isEmpty()) {
        throw new IllegalArgumentException("pathList cannot be null or empty");
    }

    for (String path : pathList) {
        try {
            new URL(path);
        } catch (MalformedURLException e) {
            throw new IllegalArgumentException("invalid URL: " + path);
        }
    }
}

private String getFileName(String path) {
    int index = path.lastIndexOf("/");
    return index >= 0 ? path.substring(index + 1) : path;
}

private String getZipFileName() {
    String UUIDStr = String.valueOf(UUID.randomUUID());
    String folderName = "invoice" + UUIDStr.replace("-", "");
    return folderName + ".zip";
}