Spring MVC“没有转换器能够从类型java.lang.String转换为类型org.springframework.core.io.Resource”

时间：2014-07-27 22:41:28

标签： java spring spring-mvc type-conversion

我们有一些自定义的“org.springframework.core.convert.converter.Converter”转换器，可帮助我们自动将休息请求中的URL参数映射到域对象。

今天我们通过定义转换服务来注册这些转换器：

<bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
    <property name="converters">
        <set>
            <!-- List of custom converter beans here -->
        </set>
    </property>
</bean>

然后使用以下方式注册：

<mvc:annotation-driven conversion-service="conversionService" />

但是，我们在每个定义的启动时都会遇到以下异常：

org.springframework.core.convert.ConversionFailedException: Failed to convert from type java.util.ArrayList<?> to type java.util.List<org.springframework.core.io.Resource> for value '[/WEB-INF/images/]'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type java.lang.String to type org.springframework.core.io.Resource

有没有人遇到/解决过这个问题？

我们正在使用spring 3.2.9。

4 个答案:

答案 0 :(得分：3)

我很高兴你还是把它分类了。我拉动了项目并自己运行它只是为了看看你的解释是正确的。如果你想在将来污染你的日志消除该消息，你可以将它添加到你的log4j.xml： - ）

<logger name="org.springframework.beans.TypeConverterDelegate">
    <level value="error" />
</logger>

答案 1 :(得分：2)

事实证明这只是我没有正确读取堆栈跟踪上方的行...错过了堆栈上方的行是“DEBUG”的事实。

简而言之，转换服务无法从String转换为Resource;然而，spring依赖于基于PropertyEditor的转换成功（我相信这是String-Resource转换正常完成的方式）。

我创建了一个示例项目，它将重新创建此调试异常：https://github.com/jamiecramb/pastebin/tree/master/conversion-test。

完整堆栈的示例如下：

DEBUG: org.springframework.beans.TypeConverterDelegate - Original ConversionService attempt failed - ignored since PropertyEditor based conversion eventually succeeded
org.springframework.core.convert.ConversionFailedException: Failed to convert from type java.util.ArrayList<?> to type java.util.List<org.springframework.core.io.Resource> for value '[/WEB-INF/css/]'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type java.lang.String to type org.springframework.core.io.Resource
    at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41)
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:168)
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:161)
    at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:448)
    at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:494)
    at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:488)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1463)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1422)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1158)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:296)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:293)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:633)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
    at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:602)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665)
    at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:521)
    at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:462)
    at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
    at javax.servlet.GenericServlet.init(GenericServlet.java:160)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1280)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1193)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1088)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5198)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5481)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:634)
    at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:671)
    at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1840)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type java.lang.String to type org.springframework.core.io.Resource
    at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:276)
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:171)
    at org.springframework.core.convert.support.CollectionToCollectionConverter.convert(CollectionToCollectionConverter.java:83)
    at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:35)
    ... 40 more

答案 2 :(得分：1)

我刚刚遇到了Spring 4.1.1的错误和FormattingConversionServiceFactoryBean的相同定义。

隐藏日志无法解决问题......在我看来，它不是一个可行的解决方案，尤其是对于生产而言。

我通过将<set></set>更改为<list></list>来修复此问题。

答案 3 :(得分：0)

我最近也遇到了这个问题。

我的Spring版本是4.1.x。一开始，我仅使用 FormattingConversionServiceFactoryBean 来配置我的自定义转换器，如下所示：

<bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
    <property name="registerDefaultFormatters" value="false" />
    <property name="converters">
        <set>
            <bean class="com.example.controller.converter.CustomerStringToDateConverter"/>
        </set>
    </property>
</bean>

<mvc:annotation-driven conversion-service="conversionService"/>

效果很好。

但是当我使用“资源服务”时，它会抛出异常

<mvc:resources mapping="/js/**" location="/js/" cache-period="31556926"/>

DEBUG [RMI TCP Connection(3)-127.0.0.1] - Original ConversionService attempt failed - ignored since PropertyEditor based conversion eventually succeeded
org.springframework.core.convert.ConversionFailedException: Failed to convert from type java.util.ArrayList<?> to type java.util.List<org.springframework.core.io.Resource> for value '[/js/]'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type java.util.ArrayList<?> to type org.springframework.core.io.Resource

解决此问题的方法是更改​​“ FormattingConversionServiceFactoryBean”的id名称，例如“ conversionService2”。

<mvc:annotation-driven conversion-service="conversionService"/>

并同时更改此引用

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