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81 lines
1.8 KiB
81 lines
1.8 KiB
package service
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import (
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"context"
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"math/rand"
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"strings"
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pb "verifyCode/api/verifyCode"
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)
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type VerifyCodeService struct {
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pb.UnimplementedVerifyCodeServer
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}
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func NewVerifyCodeService() *VerifyCodeService {
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return &VerifyCodeService{}
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}
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func (s *VerifyCodeService) GetVerifyCode(ctx context.Context, req *pb.GetVerifyCodeRequest) (*pb.GetVerifyCodeReply, error) {
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return &pb.GetVerifyCodeReply{
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Code: RandCode(int(req.Length), req.Type),
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}, nil
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}
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func RandCode(l int, t pb.TYPE) string {
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switch t {
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case pb.TYPE_DEFAULT:
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fallthrough //跟下面那个保持一样
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case pb.TYPE_DIGIT:
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return randCode("0123456789", 4, l)
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case pb.TYPE_LETTER:
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return randCode("abcdefghijklmnopqrstuvwxyz", 5, l)
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case pb.TYPE_MIXED:
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return randCode("0123456789abcdefghijklnmopqrstuvwxyz", 6, l)
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default:
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}
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return ""
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}
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//// 最简单实现版本
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//func randCode(chars string, l int) string {
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// charsLen := len(chars)
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// result := make([]byte, l)
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// for i := 0; i < l; i++ {
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// randIndex := rand.Intn(charsLen)
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// result[i] = chars[randIndex]
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// }
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// return string(result)
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//}
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func randCode(chars string, idxBits, l int) string {
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// 形成掩码
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idxMask := 1<<idxBits - 1
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// 63 位可以使用的最大组次数
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idxMax := 63 / idxBits
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// 利用string builder构建结果缓冲
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sb := strings.Builder{}
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sb.Grow(l)
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// 循环生成随机数
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// i 索引
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// cache 随机数缓存
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// remain 随机数还可以用几次
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for i, cache, remain := l-1, rand.Int63(), idxMax; i >= 0; {
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// 随机缓存不足，重新生成
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if remain == 0 {
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cache, remain = rand.Int63(), idxMax
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}
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// 利用掩码生成随机索引，有效索引为小于字符集合长度
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if idx := int(cache & int64(idxMask)); idx < len(chars) {
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sb.WriteByte(chars[idx])
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i--
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}
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// 利用下一组随机数位
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cache >>= idxBits
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remain--
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}
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return sb.String()
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}
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