Go语言中JSON解码器处理私有字段的策略与实践

package models

type Job struct {
    ScheduleTime  []CronTime
    CallbackUrl   string
    JobDescriptor string
}

type CronTime struct {
    second     int // 私有字段
    minute     int // 私有字段
    hour       int // 私有字段
    dayOfMonth int // 私有字段
    month      int // 私有字段
    dayOfWeek  int // 私有字段
}

{
    "ScheduleTime" : 
    [{
        "second" : 0,
        "minute" : 1,
        "hour" : 10,
        "dayOfMonth" : 1,
        "month" : 1,
        "dayOfWeek" : 2
    }],
    "CallbackUrl" : "SomeUrl",
    "JobDescriptor" : "SendPush"
}

package models

type CronTime struct {
    Second     int `json:"second"` // 公有字段，通过json tag映射
    Minute     int `json:"minute"`
    Hour       int `json:"hour"`
    DayOfMonth int `json:"dayOfMonth"`
    Month      int `json:"month"`
    DayOfWeek  int `json:"dayOfWeek"`
}

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"
    "strings"
)

// 假设models包定义了Job和CronTime
// type Job struct {
//     ScheduleTime  []CronTime
//     CallbackUrl   string
//     JobDescriptor string
// }

// type CronTime struct {
//     Second     int `json:"second"`
//     Minute     int `json:"minute"`
//     Hour       int `json:"hour"`
//     DayOfMonth int `json:"dayOfMonth"`
//     Month      int `json:"month"`
//     DayOfWeek  int `json:"dayOfWeek"`
// }

func addResponseHeaders(w http.ResponseWriter) {
    w.Header().Set("Content-Type", "application/json")
}

func ScheduleJob(w http.ResponseWriter, r *http.Request) {
    log.Println("Schedule a Job")
    addResponseHeaders(w)

    decoder := json.NewDecoder(r.Body)
    var job *Job // 使用修改后的Job和CronTime结构体
    err := decoder.Decode(&job)
    if err != nil {
        http.Error(w, "Failed to get request Body: "+err.Error(), http.StatusBadRequest)
        return
    }
    log.Printf("Decoded Job: %+v\n", job) // 使用%+v打印结构体详细信息
    fmt.Fprintf(w, "Job Posted Successfully to %s", r.URL.Path)
}

func main() {
    // 模拟HTTP请求
    requestBody := `{
        "ScheduleTime" : 
        [{
            "second" : 0,
            "minute" : 1,
            "hour" : 10,
            "dayOfMonth" : 1,
            "month" : 1,
            "dayOfWeek" : 2
        }],
        "CallbackUrl" : "SomeUrl",
        "JobDescriptor" : "SendPush"
    }`

    req, err := http.NewRequest("POST", "/schedule", strings.NewReader(requestBody))
    if err != nil {
        log.Fatal(err)
    }
    recorder := NewMockResponseWriter() // 模拟http.ResponseWriter

    ScheduleJob(recorder, req)
    log.Printf("Response: %s", recorder.Body.String())
}

// NewMockResponseWriter 模拟http.ResponseWriter
type MockResponseWriter struct {
    HeaderMap http.Header
    Body      strings.Builder
    Status    int
}

func NewMockResponseWriter() *MockResponseWriter {
    return &MockResponseWriter{
        HeaderMap: make(map[string][]string),
    }
}

func (m *MockResponseWriter) Header() http.Header {
    return m.HeaderMap
}

func (m *MockResponseWriter) Write(b []byte) (int, error) {
    m.Body.Write(b)
    return len(b), nil
}

func (m *MockResponseWriter) WriteHeader(statusCode int) {
    m.Status = statusCode
}

package models

import "encoding/json"

type Job struct {
    ScheduleTime  []CronTime
    CallbackUrl   string
    JobDescriptor string
}

type CronTime struct {
    second     int
    minute     int
    hour       int
    dayOfMonth int
    month      int
    dayOfWeek  int
}

// UnmarshalJSON 为 CronTime 实现 json.Unmarshaler 接口
func (c *CronTime) UnmarshalJSON(data []byte) error {
    // 定义一个匿名结构体，其字段为公有，用于临时存储解码后的数据
    // 或者使用 json tag 映射到私有字段
    type Alias CronTime // 创建一个别名类型，避免无限递归调用 UnmarshalJSON

    aux := &struct {
        Second     int `json:"second"`
        Minute     int `json:"minute"`
        Hour       int `json:"hour"`
        DayOfMonth int `json:"dayOfMonth"`
        Month      int `json:"month"`
        DayOfWeek  int `json:"dayOfWeek"`
    }{}

    if err := json.Unmarshal(data, &aux); err != nil {
        return err
    }

    // 将临时结构体中的数据赋值给 CronTime 的私有字段
    c.second = aux.Second
    c.minute = aux.Minute
    c.hour = aux.Hour
    c.dayOfMonth = aux.DayOfMonth
    c.month = aux.Month
    c.dayOfWeek = aux.DayOfWeek

    return nil
}

// 为了方便外部访问 CronTime 的值，可以提供公有方法
func (c CronTime) GetSecond() int { return c.second }
func (c CronTime) GetMinute() int { return c.minute }
// ... 其他 Getter 方法