The problem I encountered is that,when lc_messages = 'ja_JP.UTF-8' is set in postgresql.conf,and initial connection to database server failed(for example:user name,password or dbname is misspelled),I see garbled error message text in the client .The reason is that,in PGStream constrcutor,default encoding of ASCII is set(Encoding.getJVMEncoding("US-ASCII")).For the following reasons,maybe UTF8 is a better option for default encoding.
1.When initializing connection ,jdbcclient send client_encoding parameter as UTF-8
see org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(HostSpec[], String, String, Properties, Logger)
2. When initial connection to server completes,jdbc client only receive the value for client_encoding as UTF-8
see org.postgresql.core.v3.ConnectionFactoryImpl.readStartupMessages(PGStream, ProtocolConnectionImpl, Logger)
if (name.equals("client_encoding"))
{
if (!value.equals("UTF8"))
throw new PSQLException(GT.tr("Protocol error. Session setup failed."), PSQLState.PROTOCOL_VIOLATION);