go interface 转 string,解析json

package main import ( "encoding/json" "fmt" ) var user map[string]interface{} func main() { userJson := "{\"username\":\"system\",\"password\":\"123456\"}" json.Unmarshal([]byte(userJson), &user) fmt.Println(user) //打印结果:map[password:123456 username:system] username := user["username"] fmt.Println("username ==", username) //username == system //判断username的长度不为0, //if len(username) != 0 {//直接使用,报错invalid argument username (type interface {}) for len if len(username.(string)) != 0 {//通过.(string)转换成string类型 fmt.Println("输入合法") } else { fmt.Println("输入不合法") } }