Question

我正在从事热敏打印机项目，在该项目中，我使用Android Print Service从第三方应用程序中打印帐单。因为我必须打印为原始文本，所以我需要使用PrintJob从iTextPdf中提取文本。

到目前为止，一切都还不错，当时我在某些设备上看到了Crashlytics中的错误（ stacktrace bellow ）。每15个打印会话一次，他们就会遇到问题。甚至不确定我如何复制此错误，或者为什么不是每次都发生。

Caused by java.io.IOException: read failed: EBADF (Bad file number)
       at libcore.io.IoBridge.read + 435(IoBridge.java:435)
       at java.io.FileInputStream.read + 179(FileInputStream.java:179)
       at java.io.InputStream.read + 162(InputStream.java:162)
       at com.itextpdf.text.io.StreamUtil.inputStreamToArray(StreamUtil.java)
       at com.itextpdf.text.io.RandomAccessSourceFactory.createSource(RandomAccessSourceFactory.java)
       at com.itextpdf.text.pdf.PdfReader.(Unknown Source)
       at com.itextpdf.text.pdf.PdfReader.(Unknown Source)
       at sk.blockomat.vrp.pdf.PdfHelper$Companion.extractText(PdfHelper.java)
       at sk.blockomat.vrp.services.CustomPrinterService.extractPrintJobText(CustomPrinterService.java)
       at sk.blockomat.vrp.services.CustomPrinterService.onPrintJobQueued(CustomPrinterService.java)
       at android.printservice.PrintService$ServiceHandler.handleMessage + 516(PrintService.java:516)
       at android.os.Handler.dispatchMessage + 102(Handler.java:102)
       at android.os.Looper.loop + 136(Looper.java:136)
       at android.app.ActivityThread.main + 5584(ActivityThread.java:5584)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke + 515(Method.java:515)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run + 1268(ZygoteInit.java:1268)
       at com.android.internal.os.ZygoteInit.main + 1084(ZygoteInit.java:1084)
       at dalvik.system.NativeStart.main(NativeStart.java)

这是我用于PrintJob文本提取的代码：

override fun onPrintJobQueued(job: PrintJob) {
    //mark job as started
    job.start()

    //transform print job to text
    var text = extractPrintJobText(job)

    //print text
    ...
}

private fun extractPrintJobText(job: PrintJob): String {
    val descriptor = job.document.data!!.fileDescriptor

    //this stream look some way corrupted
    val stream = FileInputStream(descriptor)

    if(!stream.fd.valid()) {
        //I never saw this warning, so I expect every stream is valid
        logger.logWarning(TAG, "Stream fd is not valid!")
    }

    return extractText(stream)
}

这是我遇到错误的应用程序的一部分。

fun extractText(stream: InputStream): String {
    //line where I somethimes get EBADF (bad file number) error
    val pdfReader = PdfReader(stream)

    return extractText(pdfReader)
}

private fun extractText(pdfReader: PdfReader): String {
    val pages = pdfReader.numberOfPages
    var parsedText = ""

    try {
        for (i in 0 until pages) {
            //Extracting the content from the different pages
            parsedText += PdfTextExtractor.getTextFromPage(pdfReader, i + 1).trim() + "\n"
        }

        return parsedText
    } finally {
        pdfReader.close()
    }
}

iTextPdf：从PrintJob中提取文本

0 个答案: