当我尝试构建我的api时，我正在处理这个演示项目http://itextpdf.com/download.php我有这个错误消息（依赖项）。
Failed to execute goal on project book: Could not resolve dependencies for project
com.itextpdf:book:war:5.3.1-SNAPSHOT:
The following artifacts could not be resolved:
com.itextpdf:itextpdf:jar:5.3.1-SNAPSHOT,
com.itextpdf:itext-xtra:jar:5.3.1-SNAPSHOT,
com.itextpdf:itext-pdfa:jar:5.3.1-SNAPSHOT,
itext-pdfa:com.itextpdf:jar:5.3.1-SNAPSHOT:
Could not find artifact com.itextpdf:itextpdf:jar:5.3.1-SNAPSHOT -> [Help 1]
To see the full stack trace of the errors, re-run Maven with the -e switch.
Re-run Maven using the -X switch to enable full debug logging.
For more information about the errors and possible solutions, please read the following articles:
[Help 1] http://cwiki.apache.org/confluence/display/MAVEN/DependencyResolutionException