java 使用里面的 csv 文件动态创建 zip
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Creating a zip on the fly with csv files inside
提问by ant-depalma
I'm trying to create a zip file on the fly containing a bunch of csv files to return from a servlet and its very confusing. A little guidance would be great. Here are chunks of code I have that somehow need to work together:
我正在尝试动态创建一个 zip 文件，其中包含一堆要从 servlet 返回的 csv 文件，这非常令人困惑。一点指导会很棒。以下是我需要以某种方式协同工作的代码块：
// output stream coming from httpResponse, thats all fine
ZipOutputStream zip = new ZipOutputStream(outputStream);
// using the openCSV library to create the csv file
CSVWriter writer = new CSVWriter(Writer?);
// what writer do I use? I want to write to memory, not a file
writer.writeNext(entries);
writer.close();
// at this point should I have the csv file in memory somewhere?
//and then try to copy it into the zip file?
int length;
byte[] buffer = new byte[1024 * 32];
zip.putNextEntry(new ZipEntry(getClass() + ".csv"));
// the 'in' doesn't exist yet - where am I getting the input stream from?
while((length = in.read(buffer)) != -1)
zip.write(buffer, 0, length);
zip.closeEntry();
zip.flush();
回答by nadirsaghar
You can stream the ZIP file containing your CSVs as follows :
您可以流式传输包含 CSV 的 ZIP 文件，如下所示：
try {
OutputStream servletOutputStream = httpServletResponse.getOutputStream(); // retrieve OutputStream from HttpServletResponse
ZipOutputStream zos = new ZipOutputStream(servletOutputStream); // create a ZipOutputStream from servletOutputStream
List<String[]> csvFileContents = getContentToZIP(); // get the list of csv contents. I am assuming the CSV content is generated programmatically
int count = 0;
for (String[] entries : csvFileContents) {
String filename = "file-" + ++count + ".csv";
ZipEntry entry = new ZipEntry(filename); // create a zip entry and add it to ZipOutputStream
zos.putNextEntry(entry);
CSVWriter writer = new CSVWriter(new OutputStreamWriter(zos)); // There is no need for staging the CSV on filesystem or reading bytes into memory. Directly write bytes to the output stream.
writer.writeNext(entries); // write the contents
writer.flush(); // flush the writer. Very important!
zos.closeEntry(); // close the entry. Note : we are not closing the zos just yet as we need to add more files to our ZIP
}
zos.close(); // finally closing the ZipOutputStream to mark completion of ZIP file
} catch (Exception e) {
log.error(e); // handle error
}
