Debug http://stackoverflow.com/questions/18727284/using-read-xlsx-in-shiny-r-app/18728089

server.R

library(shiny)


shinyServer(function(input, output) {
 dataset = reactive({

    infile = input$file1  


    if (is.null(infile))
      return(NULL)

    infile_read = read.xlsx(infile$datapath, 1)

  })

 output$summary <- renderPrint({
   summary = summary(dataset())
   return(summary)
 })

  outputOptions(output, "summary", suspendWhenHidden = FALSE)

})

ui.R

library(shiny)
shinyUI(pageWithSidebar(
     headerPanel("Analysis"),
     sidebarPanel(wellPanel(fileInput('file1', 'Choose XLSX File',
          accept=c('sheetName', 'header'), multiple=FALSE))),
mainPanel(
tabsetPanel(
  tabPanel("Tab1",h4("Summary"), htmlOutput("summary"))    
)))