java iText 直接打印

iText direct Printing

提问by fareed

I am using iText to generate a pdf and write it to the file system as the following:

我正在使用 iText 生成 pdf 并将其写入文件系统，如下所示：

private void createPDF() throws Exception{
    com.itextpdf.text.Document doc = new com.itextpdf.text.Document();
    PdfWriter docWriter = null;
    path = "C:\PATH\TO\Desktop\EXAMPLE_FOLDER\" + pdfFilename;
    docWriter = PdfWriter.getInstance(doc, new FileOutputStream(path));
    doc.addTitle("Invoice");
    doc.setPageSize(PageSize.A4);
    doc.open();
    PdfContentByte cb = docWriter.getDirectContent();
    fillPDFDetails(cb);
    if (doc != null) {
        doc.close();
    }
    if (docWriter != null) {
        docWriter.close();
    }
}

However, I want to send the pdf to the printer and print the pdf file instead of writing it to the file system. How can I achieve this?

但是，我想将 pdf 发送到打印机并打印 pdf 文件，而不是将其写入文件系统。我怎样才能做到这一点？

回答by Bruno Lowagie

There's a theoretical and a practical answer to this question.

这个问题有一个理论上的和一个实际的答案。

Let's start with the theoretical answer. There's a Java class called PrintStreamthat allows you to send an OutputStreamto a printer:

让我们从理论上的答案开始。有一个 Java 类被调用PrintStream，它允许您将一个发送OutputStream到打印机：

Printstreamextends FilterOutputStreamextends OutputStream

A PrintStreamadds functionality to another output stream, namely the ability to print representations of various data values conveniently. Two other features are provided as well. Unlike other output streams, a PrintStreamnever throws an IOException; instead, exceptional situations merely set an internal flag that can be tested via the checkErrormethod. Optionally, a PrintStreamcan be created so as to flush automatically; this means that the flush method is automatically invoked after a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written.

Printstream延伸FilterOutputStream延伸OutputStream

APrintStream向另一个输出流添加功能，即方便地打印各种数据值的表示的能力。还提供了另外两个功能。与其他输出流不同，aPrintStream从不抛出IOException; 相反，异常情况仅设置一个可以通过该checkError方法进行测试的内部标志 。可选地，PrintStream可以创建 a 以便自动刷新；这意味着在写入字节数组、调用 println 方法之一或'\n'写入换行符或字节 ( )后，会自动调用刷新方法。

So, suppose that you would like to create a PDF in memory and write it to a printer, you'd do something like this:

因此，假设您想在内存中创建一个 PDF 并将其写入打印机，您可以执行以下操作：

ByteArrayOutputStream baos = new ByteArrayOutputStream();
PrintStream ps = new PrintStream(baos);
Document document = new Document();
PdfWriter.getInstance(document, ps);
document.open();
// add content
document.close();

As PrintStreamextends OutputStreamand as PdfWriteraccepts any type of OutputStream, you are writing the PDF bytes to the printer and if you want the PDF bytes, you can do baos.toByteArray().

作为PrintStream扩展OutputStream和PdfWriter接受任何类型的OutputStream，您正在将 PDF 字节写入打印机，如果您想要 PDF 字节，您可以执行baos.toByteArray().

However, the code snippet above sends PDF bytes to the printer. Chances are that your printer doesn't understand PDF and just prints out stuff like:

但是，上面的代码段将 PDF 字节发送到打印机。很有可能您的打印机不理解 PDF，只是打印出以下内容：

PDF-1.4
%a??ó
2 0 obj
<</Length 64/Filter/FlateDecode>>stream
*binary stuff*
endstream
endobj
4 0 obj
<</Parent 3 0 R/Contents 2 0 R/Type/Page/Resources<</Font<</F1 1 0 R>>>>
/MediaBox[0 0 595 842]>>
endobj
1 0 obj
<</BaseFont/Helvetica/Type/Font/Encoding/WinAnsiEncoding/Subtype/Type1>>
endobj
3 0 obj
<</Type/Pages/Count 1/Kids[4 0 R]>>
endobj
5 0 obj
<</Type/Catalog/Pages 3 0 R>>
endobj
6 0 obj
<</Producer(iText? 5.4.2 ?2000-2012 1T3XT BVBA \(AGPL-version\))
/ModDate(D:20130502165150+02'00')/CreationDate(D:20130502165150+02'00')>>
endobj
xref
0 7
0000000000 65535 f 
0000000302 00000 n 
0000000015 00000 n 
0000000390 00000 n 
0000000145 00000 n 
0000000441 00000 n 
0000000486 00000 n 
trailer
<</Root 5 0 R/ID [<91bee3a87061eb2834fb6a3258bf817e><91bee3a87061eb2834fb6a3258bf817e>]
/Info 6 0 R/Size 7>>
%iText-5.4.2
startxref
639
%%EOF

Update:

更新：

In a comment, the following link was added: https://blog.idrsolutions.com/2010/01/printing-pdf-files-from-java/

在评论中，添加了以下链接：https: //blog.idrsolutions.com/2010/01/printing-pdf-files-from-java/

This is actually a better way to print your file:

这实际上是打印文件的更好方法：

FileInputStream fis = new FileInputStream(“C:/mypdf.pdf”);
Doc pdfDoc = new SimpleDoc(fis, null, null);
DocPrintJob printJob = printService.createPrintJob();
printJob.print(pdfDoc, new HashPrintRequestAttributeSet());
fis.close();

If you don't want to use a FileInputStream, you can always create the PDF as a ByteArrayOutputStreamand use the resulting byte[]to create a ByteArrayInputStream.

如果您不想使用FileInputStream，您始终可以将 PDF 创建为 aByteArrayOutputStream并使用结果byte[]创建ByteArrayInputStream.

That's what the practical answer is about: it's not that difficult to create a PDF in memory. That's done like this:

这就是实际答案的内容：在内存中创建 PDF 并不难。这样做是这样的：

ByteArrayOutputStream baos = new ByteArrayOutputStream();
Document document = new Document();
PdfWriter.getInstance(document, baos);
document.open();
// add content
document.close();
byte[] pdf = baos.toByteArray();

The question is: what are you going to do with pdf?

问题是：你打算怎么办pdf？

Either your printer understands those bytes (there are printers that accept PDF syntax), or you'll have to find software that converts PDF into a format that printers understand. Usually, people use PDF rendering software (such as Adobe Reader) to print a document. Many of these viewers (Adobe Reader is one of them), require the file to exist as a file: Adobe Reader does not accept a byte array.

您的打印机可以理解这些字节（有些打印机可以接受 PDF 语法），或者您必须找到将 PDF 转换为打印机可以理解的格式的软件。通常，人们使用 PDF 渲染软件（例如 Adob​​e Reader）来打印文档。许多这些查看器（Adobe Reader 就是其中之一）要求文件作为文件存在：Adobe Reader 不接受字节数组。

This explains why the practical answer isn't as easy as the theoretical answer: in practice, your question is far from trivial: it depends on the printer (which formats does it accept) and the PDF viewer (should you require one).

这解释了为什么实际答案不像理论答案那么简单：在实践中，您的问题远非微不足道：它取决于打印机（它接受哪种格式）和 PDF 查看器（您是否需要）。

回答by Gerard Martinelli

Try this :

试试这个 ：

filename = "aaaaaaa.pdf";
java.io.File fileout =  new File(filename);
com.lowagie.tools.Executable.printDocumentSilent(fileout));
 fileout.delete();  // if you don't want to keep it.