问题描述：
java.lang.LinkageError: loader constraint violation: when resolving method "javax.mail.internet.MimeBodyPart.setDataHandler(Ljavax/activation/DataHandler;)V" the class loader (instance of org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader) of the current class, org/apache/axiom/om/impl/MIMEOutputUtils, and the class loader (instance of org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader) for resolved class, javax/mail/internet/MimeBodyPart, have different Class objects for the type BodyPart.setDataHandler(Ljavax/activation/DataHandler;)V used in the signature
原因：
jar包的问题，有可能是版本的问题导致的
解决方法：
把javax.mail_1.4.0.jar 替换成 mail-1.4.jar
