Servlet三件事

博客介绍了Servlet处理表单的三件事,包括获取表单数据、处理业务逻辑以及分发转向,这些操作是Servlet在处理表单时的关键步骤,属于后端开发的重要内容。

三件事:

1.获取表单数据

2.处理业务逻辑

3.分发转向

HTTP ERROR 500 java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "oldAlg" is null URI: /setup/setup-host-settings.jsp STATUS: 500 MESSAGE: java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "oldAlg" is null SERVLET: org.jivesoftware.openfire.admin.setup.setup_002dhost_002dsettings_jsp CAUSED BY: java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "oldAlg" is null Caused by: java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "oldAlg" is null at org.jivesoftware.util.JiveGlobals.setupPropertyEncryptionAlgorithm(JiveGlobals.java:1088) at org.jivesoftware.openfire.admin.setup.setup_002dhost_002dsettings_jsp._jspService(setup_002dhost_002dsettings_jsp.java:265) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:64) at javax.servlet.http.HttpServlet.service(HttpServlet.java:590) at org.eclipse.jetty.ee8.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1160) at org.eclipse.jetty.ee8.servlet.ServletHolder.handle(ServletHolder.java:649) at org.eclipse.jetty.ee8.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1374) at com.opensymphony.sitemesh.webapp.SiteMeshFilter.obtainContent(SiteMeshFilter.java:182) at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:85) at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:171) at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1348) at org.jivesoftware.util.LocaleFilter.doFilter(LocaleFilter.java:73) at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:171) at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1348) at org.jivesoftware.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:38) at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:171) at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1348) at org.jivesoftware.admin.PluginFilter.doFilter(PluginFilter.java:170) at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:171) at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1348) at org.jivesoftware.admin.AuthCheckFilter.doFilter(AuthCheckFilter.java:290) at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:177) at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1348) at org.jivesoftware.admin.ContentSecurityPolicyFilter.doFilter(ContentSecurityPolicyFilter.java:53) at org.eclipse.jetty.ee8.servlet.FilterHolder.doFilter(FilterHolder.java:171) at org.eclipse.jetty.ee8.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1348) at org.eclipse.jetty.ee8.servlet.ServletHandler.doHandle(ServletHandler.java:454) at org.eclipse.jetty.ee8.nested.ScopedHandler.handle(ScopedHandler.java:119) at org.eclipse.jetty.ee8.security.SecurityHandler.handle(SecurityHandler.java:497) at org.eclipse.jetty.ee8.nested.HandlerWrapper.handle(HandlerWrapper.java:108) at org.eclipse.jetty.ee8.nested.ScopedHandler.nextHandle(ScopedHandler.java:183) at org.eclipse.jetty.ee8.nested.SessionHandler.doHandle(SessionHandler.java:519) at org.eclipse.jetty.ee8.nested.ScopedHandler.nextHandle(ScopedHandler.java:181) at org.eclipse.jetty.ee8.nested.ContextHandler.doHandle(ContextHandler.java:885) at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:152) at org.eclipse.jetty.ee8.servlet.ServletHandler.doScope(ServletHandler.java:423) at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:150) at org.eclipse.jetty.ee8.nested.SessionHandler.doScope(SessionHandler.java:503) at org.eclipse.jetty.ee8.nested.ScopedHandler.nextScope(ScopedHandler.java:150) at org.eclipse.jetty.ee8.nested.ContextHandler.doScope(ContextHandler.java:830) at org.eclipse.jetty.ee8.nested.ScopedHandler.handle(ScopedHandler.java:117) at org.eclipse.jetty.ee8.nested.ContextHandler.handle(ContextHandler.java:1443) at org.eclipse.jetty.ee8.nested.HttpChannel$RequestDispatchable.dispatch(HttpChannel.java:1290) at org.eclipse.jetty.ee8.nested.HttpChannel.dispatch(HttpChannel.java:617) at org.eclipse.jetty.ee8.nested.HttpChannel.handle(HttpChannel.java:460) at org.eclipse.jetty.ee8.nested.ContextHandler$CoreContextHandler$CoreToNestedHandler.handle(ContextHandler.java:2512) at org.eclipse.jetty.server.handler.ContextHandler.handle(ContextHandler.java:1071) at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:151) at org.eclipse.jetty.server.Handler$Sequence.handle(Handler.java:805) at org.eclipse.jetty.server.Server.handle(Server.java:182) at org.eclipse.jetty.server.internal.HttpChannelState$HandlerInvoker.run(HttpChannelState.java:677) at org.eclipse.jetty.server.internal.HttpConnection.onFillable(HttpConnection.java:416) at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:322) at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:99) at org.eclipse.jetty.io.SelectableChannelEndPoint$1.run(SelectableChannelEndPoint.java:53) at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.runTask(AdaptiveExecutionStrategy.java:480) at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.consumeTask(AdaptiveExecutionStrategy.java:443) at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.tryProduce(AdaptiveExecutionStrategy.java:293) at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.run(AdaptiveExecutionStrategy.java:201) at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:311) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:981) at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.doRunJob(QueuedThreadPool.java:1211) at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1166) at java.base/java.lang.Thread.run(Thread.java:833)
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11-16
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