修复识别字母条码问题

src/pages/CounterMixins.js

@@ -98,7 +98,7 @@ const CounterMixins = ComposeComponent => {
       DeviceEventEmitter.addListener('onError', () => (this.busy = false));
       const handleScan = this.submitBarcode;
       // if you want to react to keyUp
-      KeyEvent.onKeyUpListener(async e => {
+      KeyEvent.onKeyDownListener(async e => {
         const {keyCode, pressedKey} = e;
         if (keyCode === 66) {
           // 回车事件