Spring MVC“找不到能夠將java.lang.String類型轉換為org.springframework.core.io.Resource類型的轉換器”

Question

我們有許多自定義的“ org.springframework.core.convert.converter.Converter”轉換器，可幫助我們將其余請求中的URL參數自動映射到我們的域對象。

今天，我們通過定義轉換服務來注冊這些轉換器：

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

然后使用以下命令進行注冊：

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

但是，對於每個定義，我們在啟動時都會遇到以下異常：

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

有人遇到過/解決過這個問題嗎？

我們使用的是Spring 3.2.9。

Answer 1

我很高興您能對它進行排序。 我拉了這個項目並自己運行了它，只是看一下，您的解釋是正確的。 如果您希望擺脫以后污染日志的消息，可以將其添加到log4j.xml中：-)

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

Answer 2

原來這只是我沒有正確讀取堆棧跟蹤上方的行...錯過了堆棧上方的行是“ DEBUG”的事實。

簡而言之，轉換服務無法將String轉換為Resource。 但是，spring依靠的是基於PropertyEditor的轉換成功（我相信這是String-Resource轉換正常完成的方式）。

我創建了一個示例項目，它將重新創建此調試異常： https : //github.com/jamiecramb/pastebin/tree/master/conversion-test 。

完整堆棧的示例如下：

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

Answer 3

我剛遇到Spring 4.1.1和FormattingConversionServiceFactoryBean的相同定義的錯誤。

隱藏日志無法解決問題...而且我認為這不是可行的解決方案，尤其是對於生產而言。

我通過將<set></set>更改為<list></list>來修復它。

Answer 4

我最近也遇到了這個問題。

我的Spring版本是4.1.x。一開始，我僅使用FormattingConversionServiceFactoryBean來配置我的自定義轉換器，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"/>

它運作良好。

但是當我使用“資源服務”時，它會拋出異常

<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

解決此問題的方法是更改​​“ FormattingConversionServiceFactoryBean”的id名稱，例如“ conversionService2”。

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

並同時更改此引用