📅 最后修改于: 2020-11-14 10:07:51 🧑 作者: Mango
IMAP是Internet消息访问协议的缩写。它是一种应用程序层Internet协议，它允许电子邮件客户端访问远程邮件服务器上的电子邮件。 IMAP服务器通常在众所周知的端口143上进行侦听。SSL上的IMAP(IMAPS)分配给端口号993。
IMAP支持联机和脱机操作模式。使用IMAP的电子邮件客户端通常将邮件保留在服务器上，直到用户明确删除它们为止。
软件包com.sun.mail.imap是JavaMail API的IMAP协议提供程序，提供对IMAP消息存储的访问。下表列出了此提供程序的接口和类：
| Class/Interface | Description |
|---|---|
| IMAPFolder.ProtocolCommand | This a simple interface for user-defined IMAP protocol commands. |
| ACL | This is a class. An access control list entry for a particular authentication identifier (user or group). |
| IMAPFolder | This class implements an IMAP folder. |
| IMAPFolder.FetchProfileItem | This a class for fetching headers. |
| IMAPMessage | This class implements an ReadableMime object. |
| IMAPMessage.FetchProfileCondition | This class implements the test to be done on each message in the folder. |
| IMAPSSLStore | This class provides access to an IMAP message store over SSL. |
| IMAPStore | This class provides access to an IMAP message store. |
| Rights | This class represents the set of rights for an authentication identifier (for instance, a user or a group). |
| Rights.Right | This inner class represents an individual right. |
| SortTerm | A particular sort criteria, as defined by RFC 5256. |
此提供者上方需要注意的几点：
该提供程序同时支持IMAP4和IMAP4rev1协议。
连接的IMAPStore维护用于与IMAP服务器通信的IMAP协议对象池。打开文件夹并需要新的IMAP协议对象后，IMAPStore将从连接池中提供它们，如果没有可用的对象，则将创建它们。关闭文件夹后，其IMAP协议对象将返回到连接池(如果为pool)。
连接的IMAPStore对象可以维护也可以不维护单独的IMAP协议对象，该对象为商店提供了与IMAP服务器的专用连接。
IMAP协议提供程序支持以下属性，可以在JavaMail Session对象中设置以下属性。属性始终设置为字符串; “类型”列描述了如何解释字符串。
| Name | Type | Description |
|---|---|---|
| mail.imap.user | String | Default user name for IMAP. |
| mail.imap.host | String | The IMAP server to connect to. |
| mail.imap.port | int | The IMAP server port to connect to, if the connect() method doesn’t explicitly specify one. Defaults to 143. |
| mail.imap.partialfetch | boolean | Controls whether the IMAP partial-fetch capability should be used. Defaults to true. |
| mail.imap.fetchsize | int | Partial fetch size in bytes. Defaults to 16K. |
| mail.imap.ignorebodystructuresize | boolean | The IMAP BODYSTRUCTURE response includes the exact size of each body part. Normally, this size is used to determine how much data to fetch for each body part. Defaults to false. |
| mail.imap.connectiontimeout | int | Socket connection timeout value in milliseconds. Default is infinite timeout. |
| mail.imap.timeout | int | Socket I/O timeout value in milliseconds. Default is infinite timeout. |
| mail.imap.statuscachetimeout | int | Timeout value in milliseconds for cache of STATUS command response. Default is 1000 (1 second). Zero disables cache. |
| mail.imap.appendbuffersize | int | Maximum size of a message to buffer in memory when appending to an IMAP folder. |
| mail.imap.connectionpoolsize | int | Maximum number of available connections in the connection pool. Default is 1. |
| mail.imap.connectionpooltimeout | int | Timeout value in milliseconds for connection pool connections. Default is 45000 (45 seconds). |
| mail.imap.separatestoreconnection | boolean | Flag to indicate whether to use a dedicated store connection for store commands. Default is false. |
| mail.imap.auth.login.disable | boolean | If true, prevents use of the non-standard AUTHENTICATE LOGIN command, instead using the plain LOGIN command. Default is false. |
| mail.imap.auth.plain.disable | boolean | If true, prevents use of the AUTHENTICATE PLAIN command. Default is false. |
| mail.imap.auth.ntlm.disable | boolean | If true, prevents use of the AUTHENTICATE NTLM command. Default is false. |
| mail.imap.proxyauth.user | String | If the server supports the PROXYAUTH extension, this property specifies the name of the user to act as. Authenticate to the server using the administrator’s credentials. After authentication, the IMAP provider will issue the PROXYAUTH command with the user name specified in this property. |
| mail.imap.localaddress | String | Local address (host name) to bind to when creating the IMAP socket. Defaults to the address picked by the Socket class. |
| mail.imap.localport | int | Local port number to bind to when creating the IMAP socket. Defaults to the port number picked by the Socket class. |
| mail.imap.sasl.enable | boolean | If set to true, attempt to use the javax.security.sasl package to choose an authentication mechanism for login. Defaults to false. |
| mail.imap.sasl.mechanisms | String | A space or comma separated list of SASL mechanism names to try to use. |
| mail.imap.sasl.authorizationid | String | The authorization ID to use in the SASL authentication. If not set, the authentication ID (user name) is used. |
| mail.imap.sasl.realm | String | The realm to use with SASL authentication mechanisms that require a realm, such as DIGEST-MD5. |
| mail.imap.auth.ntlm.domain | String | The NTLM authentication domain. |
| mail.imap.auth.ntlm.flags | int | NTLM protocol-specific flags. |
| mail.imap.socketFactory | Socket Factory | If set to a class that implements the javax.net.SocketFactory interface, this class will be used to create IMAP sockets. |
| mail.imap.socketFactory.class | String | If set, specifies the name of a class that implements the javax.net.SocketFactory interface. This class will be used to create IMAP sockets. |
| mail.imap.socketFactory.fallback | boolean | If set to true, failure to create a socket using the specified socket factory class will cause the socket to be created using the java.net.Socket class. Defaults to true. |
| mail.imap.socketFactory.port | int | Specifies the port to connect to when using the specified socket factory. Default port is used when not set. |
| mail.imap.ssl.enable | boolean | If set to true, use SSL to connect and use the SSL port by default. Defaults to false for the “imap” protocol and true for the “imaps” protocol. |
| mail.imap.ssl.checkserveridentity | boolean | If set to true, check the server identity as specified by RFC 2595. Defaults to false. |
| mail.imap.ssl.trust | String | If set, and a socket factory hasn’t been specified, enables use of a MailSSLSocketFactory. If set to “*”, all hosts are trusted. If set to a whitespace separated list of hosts, those hosts are trusted. Otherwise, trust depends on the certificate the server presents. |
| mail.imap.ssl.socketFactory | SSL Socket Factory | If set to a class that extends the javax.net.ssl.SSLSocketFactory class, this class will be used to create IMAP SSL sockets. |
| mail.imap.ssl.socketFactory.class | String | If set, specifies the name of a class that extends the javax.net.ssl.SSLSocketFactory class. This class will be used to create IMAP SSL sockets. |
| mail.imap.ssl.socketFactory.port | int | Specifies the port to connect to when using the specified socket factory. If not set, the default port will be used. |
| mail.imap.ssl.protocols | string | Specifies the SSL protocols that will be enabled for SSL connections. The property value is a whitespace separated list of tokens acceptable to the javax.net.ssl.SSLSocket.setEnabledProtocols method. |
| mail.imap.starttls.enable | boolean | If true, enables the use of the STARTTLS command (if supported by the server) to switch the connection to a TLS-protected connection before issuing any login commands. Default is false. |
| mail.imap.starttls.required | boolean | If true, requires the use of the STARTTLS command. If the server doesn’t support the STARTTLS command, or the command fails, the connect method will fail. Defaults to false. |
| mail.imap.socks.host | string | Specifies the host name of a SOCKS5 proxy server that will be used for connections to the mail server. |
| mail.imap.socks.port | string | Specifies the port number for the SOCKS5 proxy server. This should only need to be used if the proxy server is not using the standard port number of 1080. |
| mail.imap.minidletime | int | This property sets the delay in milliseconds. If not set, the default is 10 milliseconds. |
| mail.imap.enableimapevents | boolean | Enable special IMAP-specific events to be delivered to the Store’s ConnectionListener. If true, unsolicited responses received during the Store’s idle method will be sent as ConnectionEvents with a type of IMAPStore.RESPONSE. The event’s message will be the raw IMAP response string. By default, these events are not sent. |
| mail.imap.folder.class | String | Class name of a subclass of com.sun.mail.imap.IMAPFolder. The subclass can be used to provide support for additional IMAP commands. The subclass must have public constructors of the form public MyIMAPFolder(String fullName, char separator, IMAPStore store, Boolean isNamespace) and public MyIMAPFolder(ListInfo li, IMAPStore store) |
通常，应用程序不需要直接使用此包中的类。相反，他们应该使用javax.mail包(和子包)定义的API。应用程序永远不要直接构造IMAPStore或IMAPFolder的实例。相反，他们应该使用Session方法getStore来获取适当的Store对象，并从中获取Folder对象。
“配额管理”一章中演示了使用IMAP服务器的示例。