1、设置扩展包的priority属性
修改扩展包中的 extension.xml 文件,在 extension 节点中增加 priority 属性,其值就表示该扩展包的加载优先级。该值越小,表示优先级越高。有时候为了保证某个扩展包优先级最高,可以将该值设置为一个极小的值,可以为负值。
注意: 对于完全覆盖的类型(如图片、css、jsp等),优先级越高,加载顺序越前,以按文件路径找到的第1个插件包(priority值较小)为准。
对于*.patch类型,优先级越高,加载顺序越后;如果方法有覆盖的,以最后找到的插件包(priority值较小)的内容为准,这是由于patch是合并机制,js本身是同名方法,后面加载的会覆盖前面的。
对于扩展包中添加的IModule实现,优先级越高,加载顺序越前;即priority较小的扩展包中的IModule实现的activate()方法会先被调用。
请参考如下示例。
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE extension SYSTEM "extension.dtd"> <extension name="LakalaIBA" alias="LakalaIBA" desc="IBA系统-扩展包" priority="-8100" version="1.0"> <enable-jsp-processor>1</enable-jsp-processor> <!-- <servlet> <servlet-name>TestServlet</servlet-name> <servlet-class>smartbi.extension.test.TestServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>TestServlet</servlet-name> <url-pattern>/TestServlet</url-pattern> </servlet-mapping> --> </extension>
2、设置扩展包的before属性
为了设置扩展包之间的相对优先级,还可以使用 before 属性,指明当前扩展包应该在某个指定的扩展包之前加载。before 属性的值,设置为另一扩展包的"名称",对应 extension.xml 文件中 extension 节点的 name 属性值。
请参考如下示例。
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE extension SYSTEM "extension.dtd"> <extension name="LakalaIBA" alias="LakalaIBA" desc="IBA系统-扩展包" before="webmoblie" version="1.0"> <enable-jsp-processor>1</enable-jsp-processor> <!-- <servlet> <servlet-name>TestServlet</servlet-name> <servlet-class>smartbi.extension.test.TestServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>TestServlet</servlet-name> <url-pattern>/TestServlet</url-pattern> </servlet-mapping> --> </extension>
3、设置扩展包的depends属性
有时多个扩展包之间会有依赖关系,比如扩展包 B 中的 Java 类需要调用扩展包 A 中的方法。如果直接调用的话,通常会遇到 Caused by: java.lang.NoClassDefFoundError 的错误,提示我们无法找到对应类。错误的原因是,两个扩展包的 Class Loader 是不一样的。这时我们就需要设置 B 扩展包的 depends 属性为 A 扩展包了。设置方法如下。
注:目前 depends 只支持添加一个扩展包,添加两个以上会抛异常。
如果不设置 depends 属性,提示的错误信息如下。
*** 若需要导出错误日志请联系管理员 *** 未指定错误,请查看详细信息 at smartbi.framework.rmi.ClientService.execute(ClientService.java:123) at ...(...) at smartbi.framework.rmi.ClientService.execute(ClientService.java:107) Caused by: java.lang.NoClassDefFoundError: dishui/bookshelf/TianjinDishuiModule at com.test.TestMthd.getReportStatus(TestMthd.java:41) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at smartbi.framework.rmi.ClientService.execute(ClientService.java:107) at smartbi.framework.rmi.RMIServlet.processExecute(RMIServlet.java:186) at smartbi.framework.rmi.RMIServlet.doPost(RMIServlet.java:129) at javax.servlet.http.HttpServlet.service(HttpServlet.java:647) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at smartbi.extension.ExtensionFilter$2.doFilter(ExtensionFilter.java:125) at smartbi.extension.ExtensionFilter$1.doFilter(ExtensionFilter.java:114) at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:202) at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:180) at smartbi.extension.ExtensionFilter$1.doFilter(ExtensionFilter.java:114) at smartbi.extension.ExtensionFilter.doFilterInternal(ExtensionFilter.java:134) at smartbi.extension.ExtensionFilter.doFilter(ExtensionFilter.java:43) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at smartbi.freequery.filter.GZIPFilter.doFilter(GZIPFilter.java:51) at smartbi.freequery.filter.Filter.doFilter(Filter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at smartbi.framework.rmi.TransactionFilter.doFilter(TransactionFilter.java:47) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at smartbi.freequery.filter.CheckIsLoggedFilter.doFilter(CheckIsLoggedFilter.java:99) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1008) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619) Caused by: java.lang.ClassNotFoundException: dishui.bookshelf.TianjinDishuiModule at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:303) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:316) ... 44 more
4、验证扩展包加载顺序
系统启动后,可以访问“http://localhost:8080/smartbi/vision/sysmonitor.jsp”页面,查看系统中加载的各个扩展包的优先级是否正确。