Apache FOP Displaying Chinese Characters with SimSun

Many users have encountered the issue of Chinese characters displaying as "####" in PDF documents generated using Apache FOP. Resolving this issue involves a three-step process.

Firstly, it is necessary to specify the desired font-family in the FO file. By default, FOP uses the Helvetica font, which may not support Chinese characters. To specify a different font, such as SimSun, include the following line in the FO file:

...

However, this alone may not be sufficient to resolve the issue. FOP also requires a configuration to map the specified font-family to the actual font file. This configuration is specified in FOP's configuration file, typically located at conf/fop.xconf. Add the following lines to the configuration file:

/path/to/fonts

This informs FOP to automatically configure all font files within the specified directory. Alternatively, you can specify the font mapping explicitly for each font-family and style combination:

Finally, specify the configuration file when invoking FOP. From the command line, use the -c option:

fop -c /path/to/fop.xconf input.fo input.pdf

Or, if using FOP from Java code:

fopFactory.setUserConfig(new File("/path/to/fop.xconf"));

By following these steps, FOP will have the necessary information to correctly display Chinese characters with the SimSun font in generated PDF documents.