Javamail IMAP与Gmail的连接会在随机持续时间后断开

我正在使用Javamail对gmail imap服务器进行身份验证，并获取完整邮箱的消息头，一次一个，并在本地建立索引。对于几乎没有消息的收件箱，这很好。对于消息通常超过10k的收件箱，javamail imap连接会被删除（可能是由服务器删除）。需要注意的是，这种持续时间是随机的

因为我不断地一个接一个地获取消息头，所以连接不会长时间处于空闲状态，所以不能超时

------------------------------代码--------------------------------

IMAPSSLStore imapSslStore = connectToImap("imap.googlemail.com", 993, email, oauthToken,  oauthTokenSecret, getMyConsumer(), true);
System.out.println("Successfully authenticated to IMAP.\n");
Folder inbox = imapSslStore.getFolder("[Gmail]/All Mail");
inbox.open(Folder.READ_ONLY);

Message messages[] = inbox.getMessages();

for(Message message:messages) {
  System.out.println(message);
  System.out.println("MSG NO:"+message.getMessageNumber());
  System.out.println("FROM:"+message.getFrom().toString());
}

-------------------------------代码--------------------------------------------

IMAPSSLStore imapSslStore = connectToImap("imap.googlemail.com", 993, email, oauthToken,  oauthTokenSecret, getMyConsumer(), true);
System.out.println("Successfully authenticated to IMAP.\n");
Folder inbox = imapSslStore.getFolder("[Gmail]/All Mail");
inbox.open(Folder.READ_ONLY);

Message messages[] = inbox.getMessages();

for(Message message:messages) {
  System.out.println(message);
  System.out.println("MSG NO:"+message.getMessageNumber());
  System.out.println("FROM:"+message.getFrom().toString());
}

异常跟踪：

[java] javax.mail.FolderClosedException: * BYE JavaMail Exception: java.io.IOException: **Connection dropped by server?**

[java] at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:194)
[java] at org.apache.tools.ant.taskdefs.Java.run(Java.java:747)
[java] at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:201)
[java] at org.apache.tools.ant.taskdefs.Java.execute(Java.java:104)
[java] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[java] at java.lang.reflect.Method.invoke(Method.java:597)
[java] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:105)
[java] at org.apache.tools.ant.Task.perform(Task.java:348)
[java] at org.apache.tools.ant.Target.execute(Target.java:357)
[java] at org.apache.tools.ant.Target.performTasks(Target.java:385)
[java] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1329)
[java] at org.apache.tools.ant.Project.executeTarget(Project.java:1298)
[java] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
[java] at org.apache.tools.ant.Project.executeTargets(Project.java:1181)
[java] at org.apache.tools.ant.Main.runBuild(Main.java:698)
[java] at org.apache.tools.ant.Main.startAnt(Main.java:199)
[java] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:257)
[java] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:104)
[java] Caused by: javax.mail.FolderClosedException: * BYE JavaMail Exception: java.io.IOException: Connection dropped by server?
[java] at com.sun.mail.imap.IMAPMessage.loadEnvelope(IMAPMessage.java:1198)
[java] at com.sun.mail.imap.IMAPMessage.getFrom(IMAPMessage.java:233)
[java] at com.google.code.samples.xoauth.XoauthAuthenticator.main(XoauthAuthenticator.java:209)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[java] at java.lang.reflect.Method.invoke(Method.java:597)
[java] at org.apache.tools.ant.taskdefs.ExecuteJava.run(ExecuteJava.java:217)
[java] at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:152)
[java] ... 20 more
[java] --- Nested Exception ---
[java] javax.mail.FolderClosedException: * BYE JavaMail Exception: java.io.IOException: Connection dropped by server?
[java] at com.sun.mail.imap.IMAPMessage.loadEnvelope(IMAPMessage.java:1198)
[java] at com.sun.mail.imap.IMAPMessage.getFrom(IMAPMessage.java:233)
[java] at com.google.code.samples.xoauth.XoauthAuthenticator.main(XoauthAuthenticator.java:209)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[java] at java.lang.reflect.Method.invoke(Method.java:597)
[java] at org.apache.tools.ant.taskdefs.ExecuteJava.run(ExecuteJava.java:217)
[java] at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:152)
[java] at org.apache.tools.ant.taskdefs.Java.run(Java.java:747)
[java] at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:201)
[java] at org.apache.tools.ant.taskdefs.Java.execute(Java.java:104)
[java] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[java] at java.lang.reflect.Method.invoke(Method.java:597)
[java] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:105)
[java] at org.apache.tools.ant.Task.perform(Task.java:348)
[java] at org.apache.tools.ant.Target.execute(Target.java:357)
[java] at org.apache.tools.ant.Target.performTasks(Target.java:385)
[java] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1329)
[java] at org.apache.tools.ant.Project.executeTarget(Project.java:1298)
[java] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
[java] at org.apache.tools.ant.Project.executeTargets(Project.java:1181)
[java] at org.apache.tools.ant.Main.runBuild(Main.java:698)
[java] at org.apache.tools.ant.Main.startAnt(Main.java:199)
[java] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:257)
[java] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:104)

---

我使用的是独立版本的javamail（1.4.3），我一直在努力解决这个问题。非常感谢您的帮助。

您需要捕获FolderClosedException，然后再次尝试连接。 我已经面对了这个问题，并通过以下代码解决了它：

 catch (FolderClosedException ex) {
                        ex.printStackTrace();
                        ConnectPop3(Username, Password);
                        if (!folder.isOpen()) {
                            folder.open(Folder.READ_ONLY);
                            messages = folder.getMessages();
                        }
                    } 

---

你能最终解决这个问题吗？我也打算用这个…不幸的是，这仍然是个问题。我们只需要在谷歌再见后再试一次。@SaqibAli你试过我的解决方案吗？@AhmedSaleh，你的意思是在一个陷阱里？我们做了一些类似的事情。