案例一
1.1、错误描述
五月 28, 2014 9:56:48 下午 freemarker.log.JDK14LoggerFactory$JDK14Logger error
严重: Template processing error: "Expression student.course is undefined on line 15, column 24 in course.ftl."
Expression student.course is undefined on line 15, column 24 in course.ftl.
The problematic instruction:
----------
==> ${student.course} [on line 15, column 22 in course.ftl]
----------
Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression student.course is undefined on line 15, column 24 in course.ftl.
at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
at freemarker.core.Expression.getStringValue(Expression.java:118)
at freemarker.core.Expression.getStringValue(Expression.java:93)
at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.Environment.process(Environment.java:199)
at freemarker.template.Template.process(Template.java:259)
at com.you.freemarker.FreemarkerTemplate.printFtl(FreemarkerTemplate.java:77)
at com.you.test.freemarker.FreemarkerTest.studentPrint(FreemarkerTest.java:141)
at com.you.test.freemarker.FreemarkerTest.testCourse(FreemarkerTest.java:128)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Expression student.course is undefined on line 15, column 24 in course.ftl.
The problematic instruction:
----------
==> ${student.course} [on line 15, column 22 in course.ftl]
----------
Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression student.course is undefined on line 15, column 24 in course.ftl.
at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
at freemarker.core.Expression.getStringValue(Expression.java:118)
at freemarker.core.Expression.getStringValue(Expression.java:93)
at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.Environment.process(Environment.java:199)
at freemarker.template.Template.process(Template.java:259)
at com.you.freemarker.FreemarkerTemplate.printFtl(FreemarkerTemplate.java:77)
at com.you.test.freemarker.FreemarkerTest.studentPrint(FreemarkerTest.java:141)
at com.you.test.freemarker.FreemarkerTest.testCourse(FreemarkerTest.java:128)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>学生信息</title>
</head>
<body>
姓名：张三丰
性别：男
年龄：16
生日：1970-01-01
地址：湖北省武汉市武昌洪山区
QQ：78,451,214
课程：
Expression student.course is undefined on line 15, column 24 in course.ftl.
The problematic instruction:
----------
==> ${student.course} [on line 15, column 22 in course.ftl]
----------
Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression student.course is undefined on line 15, column 24 in course.ftl.
at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
at freemarker.core.Expression.getStringValue(Expression.java:118)
at freemarker.core.Expression.getStringValue(Expression.java:93)
at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.Environment.process(Environment.java:199)
at freemarker.template.Template.process(Template.java:259)
at com.you.freemarker.FreemarkerTemplate.printFtl(FreemarkerTemplate.java:77)
at com.you.test.freemarker.FreemarkerTest.studentPrint(FreemarkerTest.java:141)
at com.you.test.freemarker.FreemarkerTest.testCourse(FreemarkerTest.java:128)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
1.2、错误原因
Student类中的course属性没有赋值，而freemarker对为空的属性就会报错
课程：${student.course}
1.3、解决办法
在属性值后添加“!”
二，案例二
2.1，分析
上面的案例的前提条件是student不能为空，假如现在student为空了怎么办。
2.2，解决方案
freemarker.core.InvalidReferenceException: Expression ctt.contentType is undefined on line 46, column 91 in WEB-INF/ftl_lib/cms/style_content/style1-1_core.ftl.
百度，google半天只说ftl文件中不能带人空值，但不知如何在ftl文件中判断为空，然后容掉这个错误。后来终于找到方法：
[#if ctt.contentType??][${ctt.contentType.name} - ${ctt.ctgName}] [#else][${ctt.ctgName}][/#if]
“??”判断是否为空。
记下方便以后备用，同样希望给遇到同样问题的人带来帮助。
这种解决方案就是加一个if判断就好了。
三，案例三
1 <#list books as book>
2 <tr>
3 <td>书名:</td>
4 <td>${book}</td>
5 </tr>
6 </#list>
报错
1 freemarker.core.InvalidReferenceException: Expression books is undefined on line 9, column 24 in WEB-INF/ftl/showBook.ftl. 2 at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125) 3 at freemarker.core.IteratorBlock.accept(IteratorBlock.java:100) 4 at freemarker.core.Environment.visit(Environment.java:221) 5 at freemarker.core.MixedContent.accept(MixedContent.java:92) 6 at freemarker.core.Environment.visit(Environment.java:221) 7 at freemarker.core.Environment.process(Environment.java:199) 8 at freemarker.template.Template.process(Template.java:259) 9 at org.apache.struts2.views.freemarker.FreemarkerResult.doExecute(FreemarkerResult.java:201) 10 at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186) 11 at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:374) 12 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:278) 13 at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256) 14 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 15 at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176) 16 at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) 17 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 18 at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265) 19 at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) 20 at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) 21 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 22 at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138) 23 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 24 at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:211) 25 at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) 26 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 27 at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:211) 28 at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) 29 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 30 at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190) 31 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 32 at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75) 33 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 34 at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:90) 35 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 36 at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243) 37 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 38 at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100) 39 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 40 at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141) 41 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 42 at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145) 43 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 44 at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171) 45 at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) 46 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 47 at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176) 48 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 49 at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) 50 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 51 at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:192) 52 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 53 at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187) 54 at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) 55 at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54) 56 at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:511) 57 at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) 58 at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91) 59 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) 60 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 61 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) 62 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) 63 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) 64 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) 65 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) 66 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) 67 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857) 68 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) 69 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) 70 at java.lang.Thread.run(Thread.java:619) 71 2012-11-26 14:11:33 org.apache.catalina.core.StandardWrapperValve invoke
解决办法是：因为ftl是不能传入空值的。如果有空值 就会报这个的错误 ：
只要做一下判断就行了
<#if books ??>
</#if>
代码 如下：
1 <#if books ??>
2 <#list books as book>
3 <tr>
4 <td>书名:</td>
5 <td>${book}</td>
6 </tr>
7 </#list>
8 </#if>
四，案例四
4，1、错误描述
六月 04, 2014 11:04:03 下午 freemarker.log.JDK14LoggerFactory$JDK14Logger error
严重: Template processing error: "Expression maps.key is undefined on line 15, column 25 in map.ftl."
Expression maps.key is undefined on line 15, column 25 in map.ftl.
The problematic instruction:
----------
==> ${maps.key} [on line 15, column 23 in map.ftl]
----------
Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression maps.key is undefined on line 15, column 25 in map.ftl.
at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
at freemarker.core.Expression.getStringValue(Expression.java:118)
at freemarker.core.Expression.getStringValue(Expression.java:93)
at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
at freemarker.core.Environment.visit(Environment.java:428)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.Environment.process(Environment.java:199)
at freemarker.template.Template.process(Template.java:259)
at com.you.freemarker.FreemarkerTemplate.printFtl(FreemarkerTemplate.java:77)
at com.you.test.freemarker.FreemarkerTest.studentPrint(FreemarkerTest.java:210)
at com.you.test.freemarker.FreemarkerTest.testMap(FreemarkerTest.java:197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Expression maps.key is undefined on line 15, column 25 in map.ftl.
The problematic instruction:
----------
==> ${maps.key} [on line 15, column 23 in map.ftl]
----------
Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression maps.key is undefined on line 15, column 25 in map.ftl.
at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
at freemarker.core.Expression.getStringValue(Expression.java:118)
at freemarker.core.Expression.getStringValue(Expression.java:93)
at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
at freemarker.core.Environment.visit(Environment.java:428)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.Environment.process(Environment.java:199)
at freemarker.template.Template.process(Template.java:259)
at com.you.freemarker.FreemarkerTemplate.printFtl(FreemarkerTemplate.java:77)
at com.you.test.freemarker.FreemarkerTest.studentPrint(FreemarkerTest.java:210)
at com.you.test.freemarker.FreemarkerTest.testMap(FreemarkerTest.java:197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>freemarker处理哈希表的内建函数</title>
</head>
<body>
张三强
1----
Expression maps.key is undefined on line 15, column 25 in map.ftl.
The problematic instruction:
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==> ${maps.key} [on line 15, column 23 in map.ftl]
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Java backtrace for programmers:
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freemarker.core.InvalidReferenceException: Expression maps.key is undefined on line 15, column 25 in map.ftl.
at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
at freemarker.core.Expression.getStringValue(Expression.java:118)
at freemarker.core.Expression.getStringValue(Expression.java:93)
at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
at freemarker.core.Environment.visit(Environment.java:428)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.Environment.process(Environment.java:199)
at freemarker.template.Template.process(Template.java:259)
at com.you.freemarker.FreemarkerTemplate.printFtl(FreemarkerTemplate.java:77)
at com.you.test.freemarker.FreemarkerTest.studentPrint(FreemarkerTest.java:210)
at com.you.test.freemarker.FreemarkerTest.testMap(FreemarkerTest.java:197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
4.2、错误原因
<#assign maps={"1":"张三丰","2":"李思思","3":"张三强","4":"王五"}>
${maps["3"]}
<#assign keys=maps?keys>
<#list keys as key>
${key}----${maps.key}
</#list>
其中，${maps.key}未定义，获取hashmap中的描述不能这样取值
4.3、解决办法
<#--freemarker HashMap取值-->
<#assign maps={"1":"张三丰","2":"李思思","3":"张三强","4":"王五"}>
${maps["3"]}
<#assign keys=maps?keys>
<#list keys as key>
${key}----${maps[key]}
</#list>
正确取值：${key}----${maps[key]}
maps.key改成
maps[key]
运行结果：
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>freemarker处理哈希表的内建函数</title>
</head>
<body>
张三强
1----张三丰
2----李思思
3----张三强
4----王五
</body>
</html>