func (s *SimpleLogger) Infof(format string, v ...interface{}) {
	if s.level <= core.LOG_INFO {
		s.INFO.Output(2, fmt.Sprintf(format, v...))
	}
	return
}
Infof implement core.ILogger
package xorm
import (
	"fmt"
	"io"
	"log"
	"github.com/go-xorm/core"
)
const (
	DEFAULT_LOG_PREFIX = "[xorm]"
	DEFAULT_LOG_FLAG   = log.Ldate | log.Lmicroseconds
	DEFAULT_LOG_LEVEL  = core.LOG_DEBUG
)
var _ core.ILogger = DiscardLogger{}
type DiscardLogger struct{}
func (DiscardLogger) Debug(v ...interface{}) {}
func (DiscardLogger) Debugf(format string, v ...interface{}) {}
func (DiscardLogger) Error(v ...interface{}) {}
func (DiscardLogger) Errorf(format string, v ...interface{}) {}
func (DiscardLogger) Info(v ...interface{}) {}
func (DiscardLogger) Infof(format string, v ...interface{}) {}
func (DiscardLogger) Warn(v ...interface{}) {}
func (DiscardLogger) Warnf(format string, v ...interface{}) {}
func (DiscardLogger) Level() core.LogLevel {
	return core.LOG_UNKNOWN
}
func (DiscardLogger) SetLevel(l core.LogLevel) {}
func (DiscardLogger) ShowSQL(show ...bool) {}
func (DiscardLogger) IsShowSQL() bool {
	return false
}
type SimpleLogger struct {
	DEBUG   *log.Logger
	ERR     *log.Logger
	INFO    *log.Logger
	WARN    *log.Logger
	level   core.LogLevel
	showSQL bool
}
var _ core.ILogger = &SimpleLogger{}
func NewSimpleLogger(out io.Writer) *SimpleLogger {
	return NewSimpleLogger2(out, DEFAULT_LOG_PREFIX, DEFAULT_LOG_FLAG)
}
func NewSimpleLogger2(out io.Writer, prefix string, flag int) *SimpleLogger {
	return NewSimpleLogger3(out, prefix, flag, DEFAULT_LOG_LEVEL)
}
func NewSimpleLogger3(out io.Writer, prefix string, flag int, l core.LogLevel) *SimpleLogger {
	return &SimpleLogger{
		DEBUG: log.New(out, fmt.Sprintf("%s [debug] ", prefix), flag),
		ERR:   log.New(out, fmt.Sprintf("%s [error] ", prefix), flag),
		INFO:  log.New(out, fmt.Sprintf("%s [info]  ", prefix), flag),
		WARN:  log.New(out, fmt.Sprintf("%s [warn]  ", prefix), flag),
		level: l,
	}
}
func (s *SimpleLogger) Error(v ...interface{}) {
	if s.level <= core.LOG_ERR {
		s.ERR.Output(2, fmt.Sprint(v...))
	}
	return
}
func (s *SimpleLogger) Errorf(format string, v ...interface{}) {
	if s.level <= core.LOG_ERR {
		s.ERR.Output(2, fmt.Sprintf(format, v...))
	}
	return
}
func (s *SimpleLogger) Debug(v ...interface{}) {
	if s.level <= core.LOG_DEBUG {
		s.DEBUG.Output(2, fmt.Sprint(v...))
	}
	return
}
func (s *SimpleLogger) Debugf(format string, v ...interface{}) {
	if s.level <= core.LOG_DEBUG {
		s.DEBUG.Output(2, fmt.Sprintf(format, v...))
	}
	return
}
func (s *SimpleLogger) Info(v ...interface{}) {
	if s.level <= core.LOG_INFO {
		s.INFO.Output(2, fmt.Sprint(v...))
	}
	return
}