This is bug: 1170962. Bug description is as follows: 'Export by a V7 client of a schema in an 8i database fails with ORA-1436 if the database contains Java objects.' This bug is fixed in 817 and a patch is available for 816, however, there is not a fix for 815. The only workaround would be to use the export utility from an Oracle8 client to avoid the problem.
metalink上面的，你试验一下吧，文档的描述和你的一样Solution Description --------------------
If you do not need Java Option, first remove it by script: $ORACLE_HOME/javavm/install/rmjvm.sql (Notice that in 8.1.6 rmjvm.sql is wrong.
Before running it you should change line: "call rmjvm.run(true)" to "execute rmjvm.run(true)" This is due to [BUG:1179670]. Be careful for having large rollback segments when running it. Then login from sqlplus as SYS user and issue the following commands: SQL> drop package dbms_java; SQL> drop public synonym dbms_java; If you need the Java Option check [NOTE:105472.1] for correct Java installation. Explanation -----------
Export tests whether the Synonym 'DBMS_JAVA' is defined. If it is defined, export assumes java has been installed and it uses dbms_java.longname to get the long version of synonym names. Otherwise, it assumes it can't use dbms_java and just takes the name out of sys.syn$. It looks like DBMS_JAVA was defined but initjvm didn't run (or failed somewhere).
$ORACLE_HOME/rdbms/admin/dbmsstdx.sql
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Did you tried to change your character set by updating sys.props$ table?
If not then that might be a problem with your JVM in Oracle. Do you have this option installed in your db? Is DBMS_JAVA valid? If not you can drop and rebuild the JVM. That should take care ot the problem.