使用iText和clojure从PDF中提取页面

Question

我试图通过翻译在http://viralpatel.net/blogs/itext-tutorial-merge-split-pdf-files-using-itext-jar/找到的splitPDF方法，用clojure从pdf中提取单个页面

IOException流关闭java.io.FileOutputStream.WriteBytes（：-2）

这将阻止我在repl仍然打开时打开文档。一旦我关闭了repl，我就可以访问文档了。

为什么我会得到错误？

我怎么才能让它更clojurey？

(import '(com.itextpdf.text Document)
            '(com.itextpdf.text.pdf PdfReader PdfWriter PdfContentByte PdfImportedPage BaseFont)
            '(java.io File FileInputStream FileOutputStream InputStream OutputStream))

(defn extract-page [src dest pagenum]
  (with-open  [ d (Document.) 
                os (FileOutputStream. dest)]
    (let [ srcpdf (->> src FileInputStream. PdfReader.)
           destpdf  (PdfWriter/getInstance d os)]
         (doto d
            (.open )
            (.newPage ))
          (.addTemplate 
                (.getDirectContent destpdf)
                (.getImportedPage destpdf srcpdf pagenum) 0 0))))

Answer 1

您忘记关闭文档：

(close. d)

以下代码起作用：

(import '(com.itextpdf.text Document)
            '(com.itextpdf.text.pdf PdfReader PdfWriter PdfContentByte PdfImportedPage BaseFont)
            '(java.io File FileInputStream FileOutputStream InputStream OutputStream))

(defn extract-page [src dest pagenum]
  (with-open  [ is (FileInputStream. src)
                os (FileOutputStream. dest)]
    (let [ srcpdf (PdfReader. src)
           d (Document.)
           destpdf  (PdfWriter/getInstance d os)]
         (doto d
            (.open )
            (.newPage ))
         (println "Number of pages" (.getNumberOfPages srcpdf))
         (.addTemplate 
                (.getDirectContent destpdf)
                (.getImportedPage destpdf srcpdf pagenum) 0 0)
         (.close d))))

编辑：

(import '(org.apache.pdfbox.pdmodel PDDocument)
        '(org.apache.pdfbox.util PDFTextStripper)
        '(java.io File OutputStreamWriter FileOutputStream BufferedWriter))

(defn convert-to-text [src dest]
  (with-open [ pd (PDDocument/load (File. src))
               wr (BufferedWriter. (OutputStreamWriter. (FileOutputStream. (File. dest))))]
    (let [ stripper (PDFTextStripper.)]
      (println "Number of pages" (.getNumberOfPages pd))
      (.writeText stripper pd wr))))