go语言reflect包使用的几个场景

// reflect使用场景
package main
import (
    "errors"
    "fmt"
    "reflect"
    "reflectusage/config"
)
func main() {
    // 创建Conf实例
    conf := config.Conf{}
    opName := "create"
    conf.Op = &opName
    conf.Port = 3308
    fmt.Printf("conf.Port=%d\n\n", conf.Port)
    // 结构信息
    t := reflect.TypeOf(conf)
    // 值信息
    v := reflect.ValueOf(conf)
    printStructField(&t)
    callMethod(&v, "SayOp", []interface{}{" Db"})
    // panic: reflect: Call of unexported method
    //callMethod(&v, "getDbConf", []interface{}{})
    getTag(&t, "Op", "json")
    getTag(&t, "Op", "xml")
    getTag(&t, "nofield", "json")
}
// 场景1：遍历结构体字段名
func printStructField(t *reflect.Type) {
    fieldNum := (*t).NumField()
    for i := 0; i < fieldNum; i++ {
        fmt.Printf("conf's field: %s\n", (*t).Field(i).Name)
    }
    fmt.Println("")
}
// 场景2：调用结构体方法
func callMethod(v *reflect.Value, method string, params []interface{}) {
    // 字符串方法调用，且能找到实例conf的属性.Op
    f := (*v).MethodByName(method)
    if f.IsValid() {
        args := make([]reflect.Value, len(params))
        for k, param := range params {
            args[k] = reflect.ValueOf(param)
        }
        // 调用
        ret := f.Call(args)
        if ret[0].Kind() == reflect.String {
            fmt.Printf("%s Called result: %s\n", method, ret[0].String())
        }
    } else {
        fmt.Println("can't call " + method)
    }
    fmt.Println("")
}
// 场景3：获取结构体的tag标记
func getTag(t *reflect.Type, field string, tagName string) {
    var (
        tagVal string
        err    error
    )
    fieldVal, ok := (*t).FieldByName(field)
    if ok {
        tagVal = fieldVal.Tag.Get(tagName)
    } else {
        err = errors.New("no field named:" + field)
    }
    fmt.Printf("get struct[%s] tag[%s]: %s, error:%v\n", field, tagName, tagVal, err)
    fmt.Println("")
}
// @todo更多的使用场景

package config
type Db struct {
    Port int
    Host string
    pw   string
}
type Conf struct {
    Op       *string `json:"jsonop" xml:"xmlOpName"`
    Charlist *string
    Length   *int
    Num      *int
    Output   *string
    Input    *string
    hidden   *string
    Db
}
func (this Conf) SayOp(subname string) string {
    return *this.Op + subname
}
func (this Conf) getDbConf() Db {
    return this.Db
}