如何在python (dash)仪表板中显示png文件和csv表

import dash
import dash_core_components as dcc
import dash_html_components as html
import pandas as pd

app = dash.Dash(__name__)
app.layout = html.Div([
    html.H1('显示PNG文件和CSV表格'),
    html.Img(id='png-image'),
    html.Table(id='csv-table')
])

@app.callback(
    dash.dependencies.Output('png-image', 'src'),
    dash.dependencies.Output('csv-table', 'children'),
    [dash.dependencies.Input('upload-data', 'filename')])
def update_outputs(filename):
    if filename is not None:
        # 显示PNG文件
        png_image = dcc.Graph(figure={'data': [{'x': [1, 2, 3], 'y': [4, 1, 2], 'type': 'bar', 'name': '图表'}]})
        
        # 显示CSV表格
        csv_table = pd.read_csv(filename)
        csv_table_html = html.Table([
            html.Thead(html.Tr([html.Th(col) for col in csv_table.columns])),
            html.Tbody([
                html.Tr([
                    html.Td(csv_table.iloc[i][col]) for col in csv_table.columns
                ]) for i in range(len(csv_table))
            ])
        ])
        
        return png_image, csv_table_html
        
    return None, None

if __name__ == '__main__':
    app.run_server(debug=True)