Request suffix processed by Struts2

The request suffix specified in struts2 is specified through <constant name = "struts. action. extension" value = "do, cation"> In struts. xml. Another configuration method is through struts. properties to configure (not commonly used): sturts. action. extension = do because constants can be defined in the following configuration files, so we want to understand the search order of sturts2 loading constants: 1, struts-default.xml 2, sturts-plugin.xml 3, struts. xml 4, struts. properties 5. web. xml if the same constant is defined in multiple configuration files, the constants configured in the latter file overwrite the constant values configured in the previous file.