今天同事問我說，如何處理RECEIVE、VISIBLE的JMS消息？有點懵，之前從沒有關注過消息的狀態。Weblogic81中，我們是不能看到destination中的消息的，只能看到當前destination中，有多少message, 有多少pending的message。而92中，我們監控destination的時候，可以看到具體的message，而且message后面會跟一個state string。標題中說的RECEIVE、VISIBLE就是這個state string，其實state有很多，常見的也就是RECEIVE、VISIBLE。下面我們看看所有這些STATE在代碼（MessageInfo.java）中的解釋，

VISIBLE：Indicates that the message is visible on the destination.消息已經入列，等待被消費。

ORDERED：Indicates that the message belongs to a Unit of Order. 消息處于某個unit中。

DELAYED：Indicates that the message exists on the destination but is classified as pending because it has a scheduled delivery time or is delayed. 消息已經入列，但因為TimeToDeliver還沒有到，直到TimeToDeliver，該消息才會變成VISIBLE。或者由于客戶端消費異常，比如onMessage中出現了RuntimeException，消息被recover后，等待Redelivery Delay時間到達，然后重新發送。

RECEIVE：Indicates that the message exists on the destination but is classified as pending because it has been received but not acknowledged. The actual state may also include STATE_TRANSACTION if the receive operation was performed as part of a transaction.消息已經入列，且已經被DELIVER到某個CONSUMER，但CONSUMER的ACKNOWLEDGE還沒有收到。可能是網絡問題或客戶端設為CLIENT_ACK模式。

SEND：Indicates that the message exists on the destination but is classified as pending because it is part of a send operation that is in progress. The actual state may also include STATE_TRANSACTION if the send operation was perfromed as part of a transaction.消息已經入列，但目前send操作正在處理中（比如事務未提交），該消息對于consumer是不可用的。

TRANSACTION：Indicates that the message exists on the destination but is classified as pending because it is part of a send or receive operation that is being performed as part of a global transaction.

PAUSED：Indicates that the message exists on the destination but is being held in a pending state because of a pause operation. 消息因為PAUSE被PENDING在DEST中。

REDELIVERY_COUNT_EXCEEDED：Indicates that the message has exceeded the redelivery count set for the destination and is no longer available for consumption. 消息反復REDELIVERY的上限已經到達，這樣的消息不會被重發。

        根據消息的狀態，我們基本可以斷定JMS消息相關問題的位置，從而調查可以做到有的放矢。