iText API for PDF comparison

Question

Can I use iText API for comparing two PDF files? I have gone through various approaches on stackoverflow for comparing PDF files such as tools, some utilities such as imagemagick etc. The PDFs which I wish to compare are fiancial reports with graphs, tables and text etc. We have to compare a large number of files and would like to do it through command line utility. There is a ComparePDF command line tool but its just outputs whether two files are conatining differences. We will like to print a log of file differences. Can we accomplish this through iText?

Answer 1

What do you want to compare? iText could be used to compare structure and syntax, but... two different PDFs that look identical to the human eye, may have a completely different structure and syntax internally.

At iText, we have written JUnit tests that use GhostScript to create images of each page. These images are compared to each other on a pixel per pixel basis.

We also use iText in JUnit tests, but these tests look at the structure and the syntax more than at the content.

Answer 2

您需要使用Myers O（ND）diff算法进行PDF比较，itext或pdfbox api不提供pdf比较方法，您可以使用itext提取这些文件的文本并进行坐标处理，以后再使用Myers O（ND）diff找出差异并突出显示变化的算法。