1. 实现配置文件解析

2. 实现数据库连接

vendor/gorm.io/gorm/logger/sql.go

@@ -0,0 +1,162 @@
+package logger
+
+import (
+	"database/sql/driver"
+	"fmt"
+	"reflect"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+	"unicode"
+
+	"gorm.io/gorm/utils"
+)
+
+const (
+	tmFmtWithMS = "2006-01-02 15:04:05.999"
+	tmFmtZero   = "0000-00-00 00:00:00"
+	nullStr     = "NULL"
+)
+
+func isPrintable(s string) bool {
+	for _, r := range s {
+		if !unicode.IsPrint(r) {
+			return false
+		}
+	}
+	return true
+}
+
+// A list of Go types that should be converted to SQL primitives
+var convertibleTypes = []reflect.Type{reflect.TypeOf(time.Time{}), reflect.TypeOf(false), reflect.TypeOf([]byte{})}
+
+// RegEx matches only numeric values
+var numericPlaceholderRe = regexp.MustCompile(`\$\d+\$`)
+
+// ExplainSQL generate SQL string with given parameters, the generated SQL is expected to be used in logger, execute it might introduce a SQL injection vulnerability
+func ExplainSQL(sql string, numericPlaceholder *regexp.Regexp, escaper string, avars ...interface{}) string {
+	var (
+		convertParams func(interface{}, int)
+		vars          = make([]string, len(avars))
+	)
+
+	convertParams = func(v interface{}, idx int) {
+		switch v := v.(type) {
+		case bool:
+			vars[idx] = strconv.FormatBool(v)
+		case time.Time:
+			if v.IsZero() {
+				vars[idx] = escaper + tmFmtZero + escaper
+			} else {
+				vars[idx] = escaper + v.Format(tmFmtWithMS) + escaper
+			}
+		case *time.Time:
+			if v != nil {
+				if v.IsZero() {
+					vars[idx] = escaper + tmFmtZero + escaper
+				} else {
+					vars[idx] = escaper + v.Format(tmFmtWithMS) + escaper
+				}
+			} else {
+				vars[idx] = nullStr
+			}
+		case driver.Valuer:
+			reflectValue := reflect.ValueOf(v)
+			if v != nil && reflectValue.IsValid() && ((reflectValue.Kind() == reflect.Ptr && !reflectValue.IsNil()) || reflectValue.Kind() != reflect.Ptr) {
+				r, _ := v.Value()
+				convertParams(r, idx)
+			} else {
+				vars[idx] = nullStr
+			}
+		case fmt.Stringer:
+			reflectValue := reflect.ValueOf(v)
+			switch reflectValue.Kind() {
+			case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+				vars[idx] = fmt.Sprintf("%d", reflectValue.Interface())
+			case reflect.Float32, reflect.Float64:
+				vars[idx] = fmt.Sprintf("%.6f", reflectValue.Interface())
+			case reflect.Bool:
+				vars[idx] = fmt.Sprintf("%t", reflectValue.Interface())
+			case reflect.String:
+				vars[idx] = escaper + strings.ReplaceAll(fmt.Sprintf("%v", v), escaper, escaper+escaper) + escaper
+			default:
+				if v != nil && reflectValue.IsValid() && ((reflectValue.Kind() == reflect.Ptr && !reflectValue.IsNil()) || reflectValue.Kind() != reflect.Ptr) {
+					vars[idx] = escaper + strings.ReplaceAll(fmt.Sprintf("%v", v), escaper, escaper+escaper) + escaper
+				} else {
+					vars[idx] = nullStr
+				}
+			}
+		case []byte:
+			if s := string(v); isPrintable(s) {
+				vars[idx] = escaper + strings.ReplaceAll(s, escaper, escaper+escaper) + escaper
+			} else {
+				vars[idx] = escaper + "<binary>" + escaper
+			}
+		case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64:
+			vars[idx] = utils.ToString(v)
+		case float32:
+			vars[idx] = strconv.FormatFloat(float64(v), 'f', -1, 32)
+		case float64:
+			vars[idx] = strconv.FormatFloat(v, 'f', -1, 64)
+		case string:
+			vars[idx] = escaper + strings.ReplaceAll(v, escaper, escaper+escaper) + escaper
+		default:
+			rv := reflect.ValueOf(v)
+			if v == nil || !rv.IsValid() || rv.Kind() == reflect.Ptr && rv.IsNil() {
+				vars[idx] = nullStr
+			} else if valuer, ok := v.(driver.Valuer); ok {
+				v, _ = valuer.Value()
+				convertParams(v, idx)
+			} else if rv.Kind() == reflect.Ptr && !rv.IsZero() {
+				convertParams(reflect.Indirect(rv).Interface(), idx)
+			} else {
+				for _, t := range convertibleTypes {
+					if rv.Type().ConvertibleTo(t) {
+						convertParams(rv.Convert(t).Interface(), idx)
+						return
+					}
+				}
+				vars[idx] = escaper + strings.ReplaceAll(fmt.Sprint(v), escaper, escaper+escaper) + escaper
+			}
+		}
+	}
+
+	for idx, v := range avars {
+		convertParams(v, idx)
+	}
+
+	if numericPlaceholder == nil {
+		var idx int
+		var newSQL strings.Builder
+
+		for _, v := range []byte(sql) {
+			if v == '?' {
+				if len(vars) > idx {
+					newSQL.WriteString(vars[idx])
+					idx++
+					continue
+				}
+			}
+			newSQL.WriteByte(v)
+		}
+
+		sql = newSQL.String()
+	} else {
+		sql = numericPlaceholder.ReplaceAllString(sql, "$$$1$$")
+
+		sql = numericPlaceholderRe.ReplaceAllStringFunc(sql, func(v string) string {
+			num := v[1 : len(v)-1]
+			n, _ := strconv.Atoi(num)
+
+			// position var start from 1 ($1, $2)
+			n -= 1
+			if n >= 0 && n <= len(vars)-1 {
+				return vars[n]
+			}
+			return v
+		})
+	}
+
+	return sql
+}