How to handle the global exception at servlet filter?

Question

I cannot redirect the page or add the error message to faces context after the rollback. How do I can show the error to the client?
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
UserTransaction utx = null;
try {
InitialContext ctx = new InitialContext();
utx = (UserTransaction) ctx.lookup("java:comp/UserTransaction");
utx.begin();
EntityManager em = EntityManagerUtil.getEntityManager();
chain.doFilter(request, response);
em.flush();
utx.commit();
em.clear();
}catch(Throwable t) {
logger.error(t, t);
try {
utx.rollback();
}catch(SystemException se) {
logger.error(se, se);
} finally {
EntityManagerUtil.closeEntityManager();
}

Answer 1

If I send the error code, it will throw the following exception because the response is committed.
java.lang.IllegalStateException
java.lang.IllegalStateException
at org.apache.coyote.tomcat5.CoyoteResponseFacade.sendError(CoyoteResponseFacade.java:433)
at mo.gov.safp.eform.web.filter.EntityManagerFilter.doFilter(EntityManagerFilter.java:57)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:198)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:288)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:271)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:202)
Should I solve it?
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
UserTransaction utx = null;
try {
// Define the request and the response encoding.
request.setCharacterEncoding("UTF-8");
response.setCharacterEncoding("UTF-8");
InitialContext ctx = new InitialContext();
utx = (UserTransaction) ctx.lookup("java:comp/UserTransaction");
utx.begin();
EntityManager em = EntityManagerUtil.getEntityManager();
chain.doFilter(request, response);
em.flush();
utx.commit();
em.clear();
}catch(Throwable t) {
logger.error(t, t);
try {
utx.rollback();
}catch(SystemException se) {
logger.error(se, se);
((HttpServletResponse)response).sendError(500);
}