在R Shiny中，如何从单选按钮调用下载处理程序？

radioButtons("downloadType", label = "选择下载类型：", choices = c("CSV", "Excel"))

observeEvent(input$downloadType, {
  if (input$downloadType == "CSV") {
    # 调用CSV下载处理程序
    # ...
  } else if (input$downloadType == "Excel") {
    # 调用Excel下载处理程序
    # ...
  }
})

# CSV下载处理程序
output$downloadCSV <- downloadHandler(
  filename = "data.csv",
  content = function(file) {
    # 将数据写入CSV文件
    write.csv(data, file, row.names = FALSE)
  }
)

# Excel下载处理程序
output$downloadExcel <- downloadHandler(
  filename = "data.xlsx",
  content = function(file) {
    # 使用openxlsx包将数据写入Excel文件
    library(openxlsx)
    wb <- createWorkbook()
    addWorksheet(wb, "Sheet1")
    writeData(wb, "Sheet1", data)
    saveWorkbook(wb, file)
  }
)