进入json解码器定义，在这种情况下应作为输入

Question

I have a go code to encode struct to json object. Can anybody show me how to decode it back? The thing I don't understand is, to define decoder, what should it be as input?

package main

import "encoding/json"
import "bytes"
//import "os"
import "fmt"

func main() {
    var emptyAppendEntriesResponse bytes.Buffer
    enc := json.NewEncoder(&emptyAppendEntriesResponse)
    d := map[string]int{"apple": 5, "lettuce": 7}
    enc.Encode(d)



}

thanks

Answer 1

You can use a bytes.Buffer as both a Reader and Writer, but it's a little easier if you use a *bytes.Buffer, since you need to use a pointer anyway.

http://play.golang.org/p/NbK_D-bMML

emptyAppendEntriesResponse := bytes.NewBuffer(nil)
enc := json.NewEncoder(emptyAppendEntriesResponse)
d := map[string]int{"apple": 5, "lettuce": 7}
enc.Encode(d)

fmt.Println(string(emptyAppendEntriesResponse.Bytes()))

dec := json.NewDecoder(emptyAppendEntriesResponse)

d = map[string]int{}
dec.Decode(&d)
fmt.Printf("%+v
", d)

When you're not working directly with io streams, it's usually more convenient to use json.Marshal and json.Unmarshal, rather than creating the Encoder and Decoder.

d := map[string]int{"apple": 5, "lettuce": 7}
resp, err := json.Marshal(&d)
fmt.Println(string(resp))

d = map[string]int{}
err = json.Unmarshal(resp, &d)
fmt.Printf("%+v
", d)