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1、報錯：java.lang.IllegalAccessError: class org.xml.sax.helpers.SecuritySupport12 cannot access its superclass org.xml.sax.helpers.SecuritySupport

  原因：能夠正常部分部署在Tomcat6上的程式，部署到Tomcat7上時，會報該錯誤。

  解決辦法：

Please add metadata-complete="true" in your web.xml to override default properties of 3.0 for annotations.

    The metadata-complete attribute of the web-app element in a Web application's deployment descriptor specifies whether the Web descriptor and other related deployment descriptors for this module (such as Web service descriptors) are complete If servlet version is set to 2.4 or an earlier version, the servlet container does not process any annotations.

If the metadata-complete attribute is missing or is set to false, the default value for Servlet 2.5/3.0, and version is set to 2.5/3.0, the servlet container examines the class files of the application for servlet annotations and supports the annotations. 例如： <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0" metadata-complete="true">