在Camel(JBoss Fuse,Spring DSL特别是)中,我正在尝试使用Camel Simple表达式读取布尔值。
<simple resultType="java.lang.Boolean">${body} != null and ${body.fielda} != null and ${body.fielda.fieldb} != null and ${body.fielda.fieldb}</simple>
<simple resultType="java.lang.Boolean">${body?.fielda?.fieldb}</simple>
${body} 是一个有效的非空 POJO,'fielda' 是另一个嵌套的 POJO,fieldb 是一个布尔值。字段可以为空,但正文不是。
当字段a为非空时,我能够正确读取值。
从各种文档来源(Apache Camel Simple,JBoss Fuse)中指出:
?.
构造可用作空安全字段读取。
当 fielda 为空时,上述两种情况都会抛出 NPE,实际上我无法在此处提供空安全读取。感谢您的帮助。
堆栈如下:
java.lang.NullPointerException
at org.apache.camel.component.bean.ConstantBeanHolder.<init>(ConstantBeanHolder.java:43)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.language.bean.BeanExpression$OgnlInvokeProcessor.process(BeanExpression.java:264)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.language.bean.BeanExpression.evaluate(BeanExpression.java:114)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.language.bean.BeanExpression.evaluate(BeanExpression.java:132)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.model.language.ExpressionDefinition.evaluate(ExpressionDefinition.java:120)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.model.language.ExpressionDefinition.evaluate(ExpressionDefinition.java:112)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.builder.ExpressionBuilder$34.evaluate(ExpressionBuilder.java:843)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.support.ExpressionAdapter.evaluate(ExpressionAdapter.java:36)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.builder.BinaryPredicateSupport.matchesReturningFailureMessage(BinaryPredicateSupport.java:60)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.builder.BinaryPredicateSupport.matches(BinaryPredicateSupport.java:50)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.language.simple.ast.BinaryExpression$5.evaluate(BinaryExpression.java:227)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.util.ExpressionToPredicateAdapter.matches(ExpressionToPredicateAdapter.java:37)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.builder.SimpleBuilder.matches(SimpleBuilder.java:76)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.ChoiceProcessor.process(ChoiceProcessor.java:90)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.interceptor.TraceInterceptor.process(TraceInterceptor.java:163)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:448)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.Pipeline.process(Pipeline.java:118)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.Pipeline.process(Pipeline.java:80)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.component.direct.DirectProducer.process(DirectProducer.java:51)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.RoutingSlip$2.doInAsyncProducer(RoutingSlip.java:301)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.impl.ProducerCache.doInAsyncProducer(ProducerCache.java:304)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.RoutingSlip.processExchange(RoutingSlip.java:294)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.RoutingSlip.doRoutingSlip(RoutingSlip.java:215)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.RoutingSlip.process(RoutingSlip.java:146)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.interceptor.TraceInterceptor.process(TraceInterceptor.java:163)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.TryProcessor.process(TryProcessor.java:113)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.TryProcessor.process(TryProcessor.java:84)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.interceptor.TraceInterceptor.process(TraceInterceptor.java:163)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.Pipeline.process(Pipeline.java:118)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.Pipeline.process(Pipeline.java:80)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)[111:org.apache.camel.camel-core:2.15.1.redhat-620133]
at org.apache.camel.component.jetty.CamelContinuationServlet.service(CamelContinuationServlet.java:162)[133:org.apache.camel.camel-jetty-common:2.15.1.redhat-620133]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)[66:org.apache.geronimo.specs.geronimo-servlet_3.0_spec:1.0.0]
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1496)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.servlets.MultiPartFilter.doFilter(MultiPartFilter.java:136)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.apache.camel.component.jetty.CamelFilterWrapper.doFilter(CamelFilterWrapper.java:43)[133:org.apache.camel.camel-jetty-common:2.15.1.redhat-620133]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1467)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:501)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:429)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.Server.handle(Server.java:370)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:494)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.AbstractHttpConnection.content(AbstractHttpConnection.java:982)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:1043)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:865)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:240)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:696)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:53)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)[70:org.eclipse.jetty.aggregate.jetty-all-server:8.1.17.v20150415]
at java.lang.Thread.run(Thread.java:745)[:1.8.0_66]
<setProperty propertyName="propName">
<xpath resultType="java.lang.Boolean">//*[local-name()='NodeName'][text() = 'true']</xpath>
</setProperty>
这绝对可靠且以零安全的方式工作。我非常失望,骆驼。
您尝试使用的 ?. 语法仅适用于 Spring 表达式语言 (SPEL)。 请在此处查看骆驼文档:http://camel.apache.org/spel.html
下面是该页面中的一个示例:
<route>
<from uri="direct:foo"/>
<filter>
<spel>#{request.headers['foo'] == 'bar'}</spel>
<to uri="direct:bar"/>
</filter>
</route>
这些字段可用,则可以使用这些 getter 方法:
${body.getFielda} != null and ${body.fetFielda.getFieldb} != null
您是否尝试过切换语句?例如:
<simple>null != {${body}</simple>