如何在react/redux中“同步”使用FileReader

// React组件
import React from 'react';
import { connect } from 'react-redux';
import { uploadFile } from './actions';

class FileUploader extends React.Component {
  handleFileChange = (event) => {
    const file = event.target.files[0];
    const reader = new FileReader();
    reader.onload = this.handleFileRead;
    reader.readAsText(file);
  };

  handleFileRead = (event) => {
    const fileContent = event.target.result;
    this.props.uploadFile(fileContent);
  };

  render() {
    return (
      <div>
        <input type="file" onChange={this.handleFileChange} />
      </div>
    );
  }
}

// Redux action
export const uploadFile = (fileContent) => ({
  type: 'UPLOAD_FILE',
  payload: fileContent,
});

// Redux reducer
const initialState = {
  fileContent: '',
};

const reducer = (state = initialState, action) => {
  switch (action.type) {
    case 'UPLOAD_FILE':
      return {
        ...state,
        fileContent: action.payload,
      };
    default:
      return state;
  }
};

export default connect(null, { uploadFile })(FileUploader);