How add a file to an existing zip file using Golang

问题

We can create a zip new file and add files using Go Language.

But, how to add a new file with existing zip file using GoLang?

If we can use Create function, how to get the zip.writer reference?

Bit confused.

回答1:

After more analysis, i found that, it is not possible to add any files with the existing zip file.

But, I was able to add files with tar file by following the hack given in this URL.

回答2:

Although I have not attempted this yet with a zip file that already exists and then writing to it, I believe you should be able to add files to it.

This is code I have written to create a conglomerate zip file containing multiple files in order to expedite uploading the data to another location. I hope it helps!

type fileData struct {
    Filename string
    Body     []byte
}

func main() {
    outputFilename := "path/to/file.zip"

    // whatever you want as filenames and bodies
    fileDatas := createFileDatas()

    // create zip file
    conglomerateZip, err := os.Create(outputFilename)
    if err != nil {
        return err
    }
    defer conglomerateZip.Close()

    zipWriter := zip.NewWriter(conglomerateZip)
    defer zipWriter.Close()

    // populate zip file with multiple files
    err = populateZipfile(zipWriter, fileDatas)
    if err != nil {
        return err
    }

}

func populateZipfile(w *zip.Writer, fileDatas []*fileData) error {
    for _, fd := range fileDatas {
        f, err := w.Create(fd.Filename)
        if err != nil {
            return err
        }

        _, err = f.Write([]byte(fd.Body))
        if err != nil {
            return err
        }

        err = w.Flush()
        if err != nil {
            return err
        }
    }
    return nil
}

回答3:

This is a bit old and already has an answer, but if performance isn't a key concern for you (making the zip file isn't on a hot path for example) you can do this with the archive/zip library by creating a new writer and copying the existing files into it then adding your new content. Something like this:

zw := // new zip writer from buffer or temp file
newFileName := // file name to add
reader, _ := zip.NewReader(bytes.NewReader(existingFile), int64(len(existingFile)))
for _, file := range reader.File {
    if file.Name == newFileName {
        continue // don't copy the old file over to avoid duplicates
    }
    fw, _ := zw.Create(file.Name)
    fr, _ := file.Open()
    io.Copy(fw, fr)
    fr.Close()
}

Then you would return the new writer and append files as needed. If you aren't sure which files might overlap you can turn that if check into a function with a list of file names you will eventually add. You can also use this logic to remove a file from an existing archive.

回答4:

you can:

copy old zip items into a new zip file;
add new files into the new zip file;

zipReader, err := zip.OpenReader(zipPath)
targetFile, err := os.Create(targetFilePath)
targetZipWriter := zip.NewWriter(targetFile)

for _, zipItem := range zipReader.File {
    zipItemReader, err := zipItem.Open()
    header, err := zip.FileInfoHeader(zipItem.FileInfo())
    header.Name = zipItem.Name
    targetItem, err := targetZipWriter.CreateHeader(header)
    _, err = io.Copy(targetItem, zipItemReader)
}

addNewFiles(targetZipWriter) // IMPLEMENT YOUR LOGIC

来源：https://stackoverflow.com/questions/28513486/how-add-a-file-to-an-existing-zip-file-using-golang

标签

zip