Java Struts2列表到整数或双精度的转换无效

我是Struts2新手，在实践中使用Struts2学习。我在书中找到了一个示例，它将请求参数映射到一个列表，同时尝试将参数从默认类型字符串转换为double或integer。它假定列表没有类型信息（在Java5之前）。我有个例外

Login.jsp

 <s:form  action="LoginAction">
    <s:textfield name="username" label="Username"></s:textfield>
    <s:password name="password" label="Password"></s:password>
    <s:textfield name="age" label="Age"></s:textfield>
    <s:textfield name="name" label="First Name"></s:textfield>
    <s:textfield name="name" label="Second Name"></s:textfield>
    <s:textfield name="name" label="Last Name"></s:textfield>
    <s:submit value="Login"></s:submit>
</s:form>

}

Stacktrace

Sep 3, 2013 11:06:22 AM      
com.opensymphony.xwork2.conversion.impl.DefaultConversionFileProcessor error
SEVERE: Problem loading properties for org.shammu.actions.LoginAction
java.lang.InstantiationException: java.lang.Double
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:131)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:162)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:151)
at com.opensymphony.xwork2.conversion.impl.DefaultTypeConverterCreator.
       createTypeConverter(DefaultTypeConverterCreator.java:23)
at com.opensymphony.xwork2.conversion.impl.DefaultConversionFileProcessor.
       process(DefaultConversionFileProcessor.java:68)
at com.opensymphony.xwork2.conversion.impl.XWorkConverter.addConverterMapping
       (XWorkConverter.java:485)
at com.opensymphony.xwork2.conversion.impl.XWorkConverter.buildConverterMapping
       (XWorkConverter.java:549)
at com.opensymphony.xwork2.conversion.impl.XWorkConverter.getConverter
       (XWorkConverter.java:417)
at com.opensymphony.xwork2.conversion.impl.XWorkConverter.convertValue
       (XWorkConverter.java:282)
at com.opensymphony.xwork2.ognl.OgnlTypeConverterWrapper.convertValue
       (OgnlTypeConverterWrapper.java:39)
at ognl.OgnlRuntime.getConvertedType(OgnlRuntime.java:1080)
at ognl.OgnlRuntime.getConvertedTypes(OgnlRuntime.java:1097)
at ognl.OgnlRuntime.getConvertedMethodAndArgs(OgnlRuntime.java:1123)
at ognl.OgnlRuntime.getAppropriateMethod(OgnlRuntime.java:1209)
at ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:1223)
at ognl.OgnlRuntime.setMethodValue(OgnlRuntime.java:1494)
at ognl.ObjectPropertyAccessor.setPossibleProperty(ObjectPropertyAccessor.java:85)
at ognl.ObjectPropertyAccessor.setProperty(ObjectPropertyAccessor.java:162)
at com.opensymphony.xwork2.ognl.accessor.ObjectAccessor.setProperty
       (ObjectAccessor.java:27)
at ognl.OgnlRuntime.setProperty(OgnlRuntime.java:2332)
at com.opensymphony.xwork2.ognl.accessor.CompoundRootAccessor.setProperty
       (CompoundRootAccessor.java:78)
at ognl.OgnlRuntime.setProperty(OgnlRuntime.java:2332)
at ognl.ASTProperty.setValueBody(ASTProperty.java:127)
at ognl.SimpleNode.evaluateSetValueBody(SimpleNode.java:220)
at ognl.SimpleNode.setValue(SimpleNode.java:301)
at ognl.Ognl.setValue(Ognl.java:737)
at com.opensymphony.xwork2.ognl.OgnlUtil.setValue(OgnlUtil.java:234)
at com.opensymphony.xwork2.ognl.OgnlValueStack.trySetValue(OgnlValueStack.java:183)
at com.opensymphony.xwork2.ognl.OgnlValueStack.setValue(OgnlValueStack.java:170)
at com.opensymphony.xwork2.ognl.OgnlValueStack.setParameter 
       (OgnlValueStack.java:148)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.setParameters
       (ParametersInterceptor.java:318)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept
       (ParametersInterceptor.java:231)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept
       (MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept
       (ParametersInterceptor.java:239)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept
       (MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept
       (StaticParametersInterceptor.java:191)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept
        (MultiselectInterceptor.java:73)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept
       (CheckboxInterceptor.java:91)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept
       (FileUploadInterceptor.java:252)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept
       (ModelDrivenInterceptor.java:100)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept
       (ScopedModelDrivenInterceptor.java:141)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept
       (ChainingInterceptor.java:145)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept
      (PrepareInterceptor.java:171)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept
      (MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept
      (I18nInterceptor.java:161)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept
      (ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept
     (AliasInterceptor.java:193)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept
     (ExceptionMappingInterceptor.java:189)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction
    (ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter
    (StrutsPrepareAndExecuteFilter.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.valves.AccessLogValve.invoke(AccessLogValve.java:953)
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:1023)
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$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

这里，我放在action类的同一文件夹中的转换文件是LoginAction conversion.properties有一行

Element name=java.lang.Double

。

---

“帮助我”

这应该是

Element\u name=java.lang.Double

在您的

LoginAction conversion.properties

文件中，您实际上并没有告诉结果类型需要是什么，但必须使用什么转换器。创建转换器以扩展以下类的最简单方法：

org.apache.struts2.util.strutstypecoverter

您必须提供以下方法的实现：

convertFromString

convertToString

在您的属性文件中，您将有如下内容

年龄=

---

您还应查看以下指南：

为什么指定

名称

是

双精度

？“这毫无意义，是你的例外情况的根源。”吉姆·加里森。我知道它与列表名配合很好；但是根据那本书（Struts2在操作中），如果我们使用Java4或更少，我们可以使用属性文件指定它。作为一名学习者，实际上我想知道为什么会出现这种异常。@shamer由于语法错误，您的转换无法工作。

Sep 3, 2013 11:06:22 AM      
com.opensymphony.xwork2.conversion.impl.DefaultConversionFileProcessor error
SEVERE: Problem loading properties for org.shammu.actions.LoginAction
java.lang.InstantiationException: java.lang.Double
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:131)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:162)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:151)
at com.opensymphony.xwork2.conversion.impl.DefaultTypeConverterCreator.
       createTypeConverter(DefaultTypeConverterCreator.java:23)
at com.opensymphony.xwork2.conversion.impl.DefaultConversionFileProcessor.
       process(DefaultConversionFileProcessor.java:68)
at com.opensymphony.xwork2.conversion.impl.XWorkConverter.addConverterMapping
       (XWorkConverter.java:485)
at com.opensymphony.xwork2.conversion.impl.XWorkConverter.buildConverterMapping
       (XWorkConverter.java:549)
at com.opensymphony.xwork2.conversion.impl.XWorkConverter.getConverter
       (XWorkConverter.java:417)
at com.opensymphony.xwork2.conversion.impl.XWorkConverter.convertValue
       (XWorkConverter.java:282)
at com.opensymphony.xwork2.ognl.OgnlTypeConverterWrapper.convertValue
       (OgnlTypeConverterWrapper.java:39)
at ognl.OgnlRuntime.getConvertedType(OgnlRuntime.java:1080)
at ognl.OgnlRuntime.getConvertedTypes(OgnlRuntime.java:1097)
at ognl.OgnlRuntime.getConvertedMethodAndArgs(OgnlRuntime.java:1123)
at ognl.OgnlRuntime.getAppropriateMethod(OgnlRuntime.java:1209)
at ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:1223)
at ognl.OgnlRuntime.setMethodValue(OgnlRuntime.java:1494)
at ognl.ObjectPropertyAccessor.setPossibleProperty(ObjectPropertyAccessor.java:85)
at ognl.ObjectPropertyAccessor.setProperty(ObjectPropertyAccessor.java:162)
at com.opensymphony.xwork2.ognl.accessor.ObjectAccessor.setProperty
       (ObjectAccessor.java:27)
at ognl.OgnlRuntime.setProperty(OgnlRuntime.java:2332)
at com.opensymphony.xwork2.ognl.accessor.CompoundRootAccessor.setProperty
       (CompoundRootAccessor.java:78)
at ognl.OgnlRuntime.setProperty(OgnlRuntime.java:2332)
at ognl.ASTProperty.setValueBody(ASTProperty.java:127)
at ognl.SimpleNode.evaluateSetValueBody(SimpleNode.java:220)
at ognl.SimpleNode.setValue(SimpleNode.java:301)
at ognl.Ognl.setValue(Ognl.java:737)
at com.opensymphony.xwork2.ognl.OgnlUtil.setValue(OgnlUtil.java:234)
at com.opensymphony.xwork2.ognl.OgnlValueStack.trySetValue(OgnlValueStack.java:183)
at com.opensymphony.xwork2.ognl.OgnlValueStack.setValue(OgnlValueStack.java:170)
at com.opensymphony.xwork2.ognl.OgnlValueStack.setParameter 
       (OgnlValueStack.java:148)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.setParameters
       (ParametersInterceptor.java:318)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept
       (ParametersInterceptor.java:231)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept
       (MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept
       (ParametersInterceptor.java:239)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept
       (MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept
       (StaticParametersInterceptor.java:191)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept
        (MultiselectInterceptor.java:73)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept
       (CheckboxInterceptor.java:91)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept
       (FileUploadInterceptor.java:252)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept
       (ModelDrivenInterceptor.java:100)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept
       (ScopedModelDrivenInterceptor.java:141)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept
       (ChainingInterceptor.java:145)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept
      (PrepareInterceptor.java:171)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept
      (MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept
      (I18nInterceptor.java:161)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept
      (ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept
     (AliasInterceptor.java:193)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
      (DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept
     (ExceptionMappingInterceptor.java:189)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke
       (DefaultActionInvocation.java:246)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction
    (ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter
    (StrutsPrepareAndExecuteFilter.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.valves.AccessLogValve.invoke(AccessLogValve.java:953)
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:1023)
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$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)