Refactor Java code to eliminate "unsafe" and "deprecated" warnings

[zhudock]

Following output when compiling Java objects in database

Note: FILE_TYPE_JAVA uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: FILE_TYPE_JAVA uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

Note: OS_HELPER uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: OS_HELPER uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.