我正在嘗試將帶有結構鍵的地圖存儲在文件中，因此我將其與 JSON 進行了轉換。但是我最終得到的地圖只有一個帶有零鍵的條目，以及原始地圖的最后一個值。（我這里的示例代碼不執行文件 I/O。）我查看了各種似乎有效的類似示例，但我看不出我哪里出錯了。import (    "encoding/json"    "errors"    "fmt")type XY struct {    X int    Y int}func (xy XY) String() string {    return fmt.Sprintf("{X:%v, Y:%v}", xy.X, xy.Y)}func (xy XY) MarshalText() ([]byte, error) {    text := []byte(fmt.Sprintf("%d,%d", xy.X, xy.Y))    fmt.Printf("Marshalled %v to %s\n", xy, text)    return text, nil}func (xy XY) UnmarshalText(p []byte) error {    n, err := fmt.Sscanf(string(p), "%d,%d", &xy.X, &xy.Y)    if err != nil {        return err    } else if n != 2 {        return errors.New("Cannot parse as XY: '" + string(p) + "'")    }    fmt.Printf("Unmarshalled %s to %v\n", p, xy)    return nil}type XYMap = map[XY]stringfunc loadXY(data []byte, xymap XYMap) error {    err := json.Unmarshal(data, &xymap)    if err != nil {        fmt.Println("unmarshal error:", err)    }    return err}func main() {    xymap := make(XYMap)    xymap[XY{1,2}] = "one two"    xymap[XY{3,4}] = "three four"    bytes, err := json.Marshal(xymap)    fmt.Printf("xymap=%v  \nbytes=%s  err=%v\n", xymap, bytes, err)    newxymap := make(XYMap)    loadXY(bytes, newxymap)    fmt.Printf("newxymap=%v\n", newxymap)}輸出：Marshalled {X:1, Y:2} to 1,2Marshalled {X:3, Y:4} to 3,4xymap=map[{X:1, Y:2}:one two {X:3, Y:4}:three four]  bytes={"1,2":"one two","3,4":"three four"}  err=<nil>Unmarshalled 1,2 to {X:1, Y:2}Unmarshalled 3,4 to {X:3, Y:4}newxymap=map[{X:0, Y:0}:three four]