server.R

library(shiny)
require(maptools)

shinyServer(function(input, output) {
  
  uploadShpfile <- reactive({
    if (!is.null(input$shpFile)){
      shpDF <- input$shpFile
      prevWD <- getwd()
      uploadDirectory <- dirname(shpDF$datapath[1])
      setwd(uploadDirectory)
      for (i in 1:nrow(shpDF)){
        file.rename(shpDF$datapath[i], shpDF$name[i])
      }
      shpName <- shpDF$name[grep(x=shpDF$name, pattern="*.shp")]
      shpPath <- paste(uploadDirectory, shpName, sep="/")
      setwd(prevWD)
      shpFile <- readShapePoly(shpPath)
      return(shpFile)
    } else {
      return()
    }
  })
  
   
  output$map <- renderPlot({
    if (!is.null(uploadShpfile())){
      plot(uploadShpfile())
  }
  })
})

ui.R

library(shiny)

shinyUI(pageWithSidebar(

  headerPanel("Shapefile plot"),
  sidebarPanel(
  fileInput(inputId="shpFile", label="Shp", multiple=TRUE)),
  mainPanel(
    plotOutput("map")
  )
))