PHP无法通过Golang解压缩gzip数据

Question

Why can't decompress gzip data by Go in my PHP demo, but PHP gzip data to Go is successful? I need post gzip JSON data from Go to PHP API service.

Test result

 -> |  php   |  go 
---------------------
php |  ok    |  ok
go  |  fail  |  ok

PHP code

class GzipDemo
{
    public function gzen($data, $file){
       $json_data = json_encode($data);
       $gz_data = gzencode($json_data,9);
       file_put_contents($file,$gz_data);
    }

    public function gzdn($file){
       $data = file_get_contents($file);
        $unpacked = gzdecode($data);
        if ($unpacked === FALSE)
        {
            print("failed:".$file."
");
        }else{
             print($file. " result Data :".$unpacked ."
");
        }
    }
}

$demo = new GzipDemo();
$file="phpgzip.txt";
$demo->gzen("data",$file);
$demo->gzdn($file);
$demo->gzdn("gogzip.txt");

This result: PHP to PHP okay. Go to PHP fail.

Go code

package main

import (
    "bytes"
    "compress/gzip"
    "encoding/json"
    "fmt"
    "io/ioutil"
    "os"
)

func main() {
    gzen("data", "gogzip.txt")
    gden("gogzip.txt")
    gden("phpgzip.txt")
}
func gzen(data string, file string) {
    b, _ := json.Marshal(data)
    buffer := new(bytes.Buffer)
    w, _ := gzip.NewWriterLevel(buffer, gzip.BestCompression)
    defer w.Close()
    w.Write(b)
    w.Flush()
    ioutil.WriteFile(file, buffer.Bytes(), os.ModePerm)
}
func gden(file string) {
    b, _ := ioutil.ReadFile(file)
    buffer := new(bytes.Buffer)
    buffer.Write(b)
    r, _ := gzip.NewReader(buffer)
    defer r.close()
    data, _ := ioutil.ReadAll(r)
    fmt.Println(file, " result Data:", string(data))
}

This result: Go to Go okay. PHP to Go okay.

Answer 1

It works with the following changes:

• In your PHP code you want to use gzdecode instead of gzinflate. And you don't need this substr($data, 10) stuff if you use that. I didn't read up on how deflate relates to gzip but the simplicity is that gzencode/gzdecode match what the golang gzip package does and what the gz* family of GNU command line tools do.
• In your Go code move your gzip.Writer.Close() call to be done before you read from buffer. As you can see here: http://golang.org/src/compress/gzip/gzip.go?s=6230:6260#L240 there is some additional stuff that is written to the underlying stream upon close, so in your example above what you are writing is incomplete. (The defer statement causes Close() to be run after the containing function exits.) Most likely the Go gzip decoding is managing to decode anyway whereas the PHP implementation is not - in any case you should properly close the stream to your in memory buffer to ensure it is complete before writing it out to a file.

OBLIGATORY NOTE: You are ignoring all of your errors in your Go code. This code looks like just a test so I won't belabor the point but you definitely want to be doing proper error handling (either reporting the problem to the user or to the caller of your function).