EMChatManager.importMessages没有作用？

EMMessage mm = EMMessage.createReceiveMessage(EMMessage.Type.TXT);

//mm.setMsgId("217853292590401555");

mm.setFrom("klkluhv9z1t45wsfv0c712_zi0xlzqpi");

mm.setTo("r29fiihls0ihz17z3aq9w5mj9ne1ccw9");

mm.setMsgTime(new Date().getTime());

//mm.setStatus(EMMessage.Status.SUCCESS);

mm.setChatType(EMMessage.ChatType.Chat);

EMTextMessageBody body = new EMTextMessageBody("created on the fly");

mm.addBody(body);



List ms = new ArrayList();

ms.add(mm);

EMClient.getInstance().chatManager().importMessages(ms);