我尝试在jsf中为h：inputFile标记创建转换器。发生了什么事情，转换器getAsObject被正确调用，但返回的对象似乎没有在标记中使用。它仍然使用未转换的。
甚至可以为h：inputFile使用转换器？
更新：我使用带有glassfish 4的netbeans 8来运行代码。请求代码示例，所以在这里。
转换器实现 javax.faces.convert.Converter 接口，因为我不知道是否有特殊的文件转换器：
@ManagedBean
@ApplicationScoped
public class ImageConverter implements Converter{
@Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
System.out.println("ImageConverter getAsObject:" +value); // this is how I know its called
return new ImageCanvas();
}
@Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
System.out.println("ImageConverter getAsString called: "+value.toString()); // just do it
return "";
}
}
我知道 getAsObject 中的值参数不会包含文件的内容，但至少要调用该方法，因为转换器 h：inputFile 标记的属性是允许的。 ImageCanvas 类不包含任何魔法，因此不会导致任何问题。
这是jsf页面：
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:comp="http://java.sun.com/jsf/composite/components">
<h:body>
<h:form enctype="multipart/form-data" >
<h:inputFile value="#{submitAsImageCanvas.image}" converter="#{imageConverter}"/>
<h:commandButton value="submit" action="#{submitAsImageCanvas.submit()}" />
</h:form>
</h:body>
</html>
这是viewScoped bean，它希望 image 属性为 ImageCanvas ：
@Named
@ViewScoped
public class SubmitAsImageCanvas implements Serializable{
private ImageCanvas image;
public ImageCanvas getImage() {
return image;
}
public void setImage(ImageCanvas image) {
this.image = image;
}
public void submit() {
System.out.println("Submit called");
}
}
当我请求jsf页面然后提交文件时，这就是netbeans输出的内容：
FATAL: JSF1073: javax.faces.component.UpdateModelException caught during processing of UPDATE_MODEL_VALUES 4 : UIComponent-ClientId=j_idt3-j_idt4, Message=javax.el.ELException: /uploadConverterImageCanvas.xhtml @8,94 value="#{submitAsImageCanvas.image}": java.lang.IllegalArgumentException: Cannot convert File name=test.txt, StoreLocation=%USERPATH%\AppData\Roaming\NetBeans\8.0\config\GF_4.0\domain1\generated\jsp\AdApp\upload__6fff2383_14717f72869__7ff1_00000200.tmp, size=4bytes, isFormField=false, FieldName=j_idt3-j_idt4 of type class org.apache.catalina.fileupload.PartItem to class model.ad.ImageCanvas
FATAL: javax.el.ELException: /uploadConverterImageCanvas.xhtml @8,94 value="#{submitAsImageCanvas.image}": java.lang.IllegalArgumentException: Cannot convert File name=test.txt, StoreLocation=%USERPATH%\AppData\Roaming\NetBeans\8.0\config\GF_4.0\domain1\generated\jsp\AdApp\upload__6fff2383_14717f72869__7ff1_00000200.tmp, size=4bytes, isFormField=false, FieldName=j_idt3-j_idt4 of type class org.apache.catalina.fileupload.PartItem to class model.ad.ImageCanvas
javax.faces.component.UpdateModelException: javax.el.ELException: /uploadConverterImageCanvas.xhtml @8,94 value="#{submitAsImageCanvas.image}": java.lang.IllegalArgumentException: Cannot convert File name=test.txt, StoreLocation=%USERPATH%\AppData\Roaming\NetBeans\8.0\config\GF_4.0\domain1\generated\jsp\AdApp\upload__6fff2383_14717f72869__7ff1_00000200.tmp, size=4bytes, isFormField=false, FieldName=j_idt3-j_idt4 of type class org.apache.catalina.fileupload.PartItem to class model.ad.ImageCanvas
at javax.faces.component.UIInput.updateModel(UIInput.java:867)
at javax.faces.component.UIInput.processUpdates(UIInput.java:749)
at javax.faces.component.UIForm.processUpdates(UIForm.java:281)
at javax.faces.component.UIComponentBase.processUpdates(UIComponentBase.java:1286)
at javax.faces.component.UIComponentBase.processUpdates(UIComponentBase.java:1286)
at javax.faces.component.UIViewRoot.processUpdates(UIViewRoot.java:1254)
at com.sun.faces.lifecycle.UpdateModelValuesPhase.execute(UpdateModelValuesPhase.java:78)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:745)
Caused by: javax.el.ELException: /uploadConverterImageCanvas.xhtml @8,94 value="#{submitAsImageCanvas.image}": java.lang.IllegalArgumentException: Cannot convert File name=test.txt, StoreLocation=%USERPATH%\AppData\Roaming\NetBeans\8.0\config\GF_4.0\domain1\generated\jsp\AdApp\upload__6fff2383_14717f72869__7ff1_00000200.tmp, size=4bytes, isFormField=false, FieldName=j_idt3-j_idt4 of type class org.apache.catalina.fileupload.PartItem to class model.ad.ImageCanvas
at com.sun.faces.facelets.el.TagValueExpression.setValue(TagValueExpression.java:139)
at javax.faces.component.UIInput.updateModel(UIInput.java:832)
... 36 more
Caused by: javax.el.ELException: java.lang.IllegalArgumentException: Cannot convert File name=test.txt, StoreLocation=%USERPATH%\AppData\Roaming\NetBeans\8.0\config\GF_4.0\domain1\generated\jsp\AdApp\upload__6fff2383_14717f72869__7ff1_00000200.tmp, size=4bytes, isFormField=false, FieldName=j_idt3-j_idt4 of type class org.apache.catalina.fileupload.PartItem to class model.ad.ImageCanvas
at com.sun.el.ExpressionFactoryImpl.coerceToType(ExpressionFactoryImpl.java:79)
at javax.el.ELContext.convertToType(ELContext.java:473)
at com.sun.el.lang.EvaluationContext.convertToType(EvaluationContext.java:166)
at com.sun.el.parser.AstValue.setValue(AstValue.java:235)
at com.sun.el.ValueExpressionImpl.setValue(ValueExpressionImpl.java:294)
at org.jboss.weld.el.WeldValueExpression.setValue(WeldValueExpression.java:64)
at com.sun.faces.facelets.el.TagValueExpression.setValue(TagValueExpression.java:131)
... 37 more
Caused by: java.lang.IllegalArgumentException: Cannot convert File name=test.txt, StoreLocation=%USERPATH%\AppData\Roaming\NetBeans\8.0\config\GF_4.0\domain1\generated\jsp\AdApp\upload__6fff2383_14717f72869__7ff1_00000200.tmp, size=4bytes, isFormField=false, FieldName=j_idt3-j_idt4 of type class org.apache.catalina.fileupload.PartItem to class model.ad.ImageCanvas
at com.sun.el.lang.ELSupport.coerceToType(ELSupport.java:417)
at com.sun.el.ExpressionFactoryImpl.coerceToType(ExpressionFactoryImpl.java:77)
... 43 more
换句话说，它是否告诉我它没有尝试使用我的转换器，因为转换器 getAsObject 方法从未被调用（因为没有调用系统打印）？
所以我尝试简单地通过将 ImageCanvas 中的属性类图像更改为bean SubmitAsImageCanvas中的 Part 来回答这个问题：
@Named
@ViewScoped
public class SubmitAsImageCanvas implements Serializable{
private Part image;
public Part getImage() {
return image;
}
public void setImage(Part image) {
this.image = image;
}
public void submit() {
System.out.println("Submit called");
}
}
所以这就是netbeans：
Info: Submit called
Info: ImageConverter getAsString called: File name=test.txt, StoreLocation=%USERPATH%\AppData\Roaming\NetBeans\8.0\config\GF_4.0\domain1\generated\jsp\AdApp\upload__6fff2383_14717f72869__7ff1_00000204.tmp, size=4bytes, isFormField=false, FieldName=j_idt3-j_idt4
好的，没有异常和 getAsObject 没有被调用，因此它永远不会尝试将其转换为对象。提交后页面刷新和 getAsString 被调用，以便将标记的值属性赋予字符串对吗？
为什么我要将转换器与文件一起使用？我不想在视图bean setter / getters中进行转换，因为转换器会分割代码并使这些bean干净简单。我也希望＆＃34;转换＆＃34;将文件转换为图像。 Part 对象不可序列化（？），我将使用可能发送到远程bean的小文件。
回到我的问题，转换器是否支持文件？在扩展课程时，这只是一个漫长的过程吗？为什么有一个转换器属于FILEINPUT的属性？