获取并设置itext pdf文档的元数据 [英] Get and set metadata for itext pdf document

问题描述

我有一个iText 文档对象，我想在其中写入一些元数据或从中读取。

我该怎么做？

I have an iText Document object and I want to write some metadata into it or read from it.
How can I do that?

想象一下，该文档传递给的方法如下：

Imagine that the document is beeing passed to a method like :

public void prePreccess(Object document) {
    Document pdfDocument =   ((Document) document);
    //What to do here with pdfDocument?
}

推荐答案

你想填充PDF的信息词典？这在 MetadataPdf 示例中进行了解释：

Do you want to populate the info dictionary of a PDF? That's explained in the MetadataPdf example:

// step 1
Document document = new Document();
// step 2
PdfWriter.getInstance(document, new FileOutputStream(filename));
// step 3
document.addTitle("Hello World example");
document.addAuthor("Bruno Lowagie");
document.addSubject("This example shows how to add metadata");
document.addKeywords("Metadata, iText, PDF");
document.addCreator("My program using iText");
document.open();
// step 4
document.add(new Paragraph("Hello World"));
// step 5
document.close();

是否要设置XMP元数据？ MetadataXmp 示例中对此进行了解释：

Do you want to set the XMP metadata? This is explained in the MetadataXmp example:

// step 1
Document document = new Document();
// step 2
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(RESULT1));
ByteArrayOutputStream os = new ByteArrayOutputStream();
XmpWriter xmp = new XmpWriter(os);
XmpSchema dc = new com.itextpdf.text.xml.xmp.DublinCoreSchema();
XmpArray subject = new XmpArray(XmpArray.UNORDERED);
subject.add("Hello World");
subject.add("XMP & Metadata");
subject.add("Metadata");
dc.setProperty(DublinCoreSchema.SUBJECT, subject);
xmp.addRdfDescription(dc);
PdfSchema pdf = new PdfSchema();
pdf.setProperty(PdfSchema.KEYWORDS, "Hello World, XMP, Metadata");
pdf.setProperty(PdfSchema.VERSION, "1.4");
xmp.addRdfDescription(pdf);
xmp.close();
writer.setXmpMetadata(os.toByteArray());
// step 3
document.open();
// step 4
document.add(new Paragraph("Hello World"));
// step 5
document.close();

请注意，此方法已弃用：我们最近更换了XMP功能，但我们仍需编写一些使用新代码的例子。

Note that this method is deprecated: we have replaced the XMP functionality recently, but we still have to write some examples using the new code.

也许你想设置填充信息字典并同时创建XMP元数据：

Maybe you want to set populate the info dictionary and create the XMP metadata at the same time:

// step 1
Document document = new Document();
// step 2
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(filename));
document.addTitle("Hello World example");
document.addSubject("This example shows how to add metadata & XMP");
document.addKeywords("Metadata, iText, step 3");
document.addCreator("My program using 'iText'");
document.addAuthor("Bruno Lowagie");
writer.createXmpMetadata();
// step 3
document.open();
// step 4
document.add(new Paragraph("Hello World"));
// step 5
document.close();

如果我是你，我会使用这个选项，因为它是最完整的解决方案。

If I were you, I'd use this option because it's the most complete solution.

您不应该从文档对象中读取元数据。

You should not read the metadata from a Document object.

您可以从现有PDF中读取XMP流，如下所示：

You can read the XMP stream from an existing PDF like this:

public void readXmpMetadata(String src, String dest) throws IOException {
    PdfReader reader = new PdfReader(src);
    FileOutputStream fos = new FileOutputStream(dest);
    byte[] b = reader.getMetadata();
    fos.write(b, 0, b.length);
    fos.flush();
    fos.close();
    reader.close();
}

您可以像这样阅读信息词典中的条目：

You can read the entries in the info dictionary like this:

PdfReader reader = new PdfReader(src);
PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));
Map<String, String> info = reader.getInfo();

info 对象将包含一系列在PDF中存储为元数据的键和值。

The info object will contain a series of keys and values that are stored as metadata inside the PDF.

这篇关于获取并设置itext pdf文档的元数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！