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@xyproto
Created June 24, 2015 10:14
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gzip compression/decompression example
package main
import (
"fmt"
"compress/gzip"
"io"
"io/ioutil"
"bytes"
"log"
)
// Write gzipped data to a Writer
func gzipWrite(w io.Writer, data []byte) error {
// Write gzipped data to the client
gw, err := gzip.NewWriterLevel(w, gzip.BestSpeed)
defer gw.Close()
gw.Write(data)
return err
}
// Write gunzipped data to a Writer
func gunzipWrite(w io.Writer, data []byte) error {
// Write gzipped data to the client
gr, err := gzip.NewReader(bytes.NewBuffer(data))
defer gr.Close()
data, err = ioutil.ReadAll(gr)
if err != nil {
return err
}
w.Write(data)
return nil
}
func main() {
s := "some data"
fmt.Println("original:\t", s)
var buf bytes.Buffer
err := gzipWrite(&buf, []byte(s))
if err != nil {
log.Fatal(err)
}
fmt.Println("compressed:\t", buf.String())
var buf2 bytes.Buffer
err = gunzipWrite(&buf2, buf.Bytes())
if err != nil {
log.Fatal(err)
}
fmt.Println("decompressed:\t", buf2.String())
}
@Shailesh1994
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If you to compress an xml file which is in the same directory where your program is saved how can we save the gzip file that you created.

@xyproto
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Author

xyproto commented Jan 30, 2020

@Shailesh1994 Here's one way:

data, err := ioutil.ReadFile("test.xml")
if err != nil {
    log.Fatal(err)
}

file, err := os.Create("test.xml.gz")
if err != nil {
    log.Fatal(err)
}

err = gzipWrite(file, data)
if err != nil {
    log.Fatal(err)
}

@Shailesh1994
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Shailesh1994 commented Jan 30, 2020 via email

@Shailesh1994
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Do you have a Read Me file of following code and I want to integrate this code for the sitemap .Can you help me out if possible

@xyproto
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xyproto commented Feb 5, 2020

I don't understand the question. Please try Stack Overflow.

@leobrines
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leobrines commented Feb 20, 2020

Thanks for the examples!!

Maybe it might be better to use io.Copy when you write?

func gunzipWrite(w io.Writer, data []byte) error {
	// Write gzipped data to the client
	gr, err := gzip.NewReader(bytes.NewBuffer(data))
	defer gr.Close()

	_, err := io.Copy(w, gr)
        return err
}

@xyproto
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Author

xyproto commented Feb 20, 2020

Yes, io.Copy is probably better.

@Tanmay451
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can we read gz file in chunks?

@xyproto
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Author

xyproto commented Aug 4, 2020

Yes, just use io.CopyN instead of io.Copy.

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