Dear list,
I noticed a problem in Camel 2.x with type conversion of Enums. It
cannot be used with constructor type Enums. The conversion of Strings to
Enum types is hard coded to fail with an Exception if the EnumConverter
cannot instantiate an Enum value.
Given the Enum:
enum Toggle {
On(true), Off(false);
private final boolean b;
Toggle(boolean b) {
this.b = b;
}
@Override
public String toString() {
return String.format("%s(%b)", name(), b);
}
}
A call to convertTo() can only find the appropriate Enum object by name:
CamelContext context = new DefaultCamelContext();
Toggle toggle = context.getTypeConverter().convertTo(Toggle.class,
"On");
System.out.println(toggle); // ...On(true)
However, I cannot introduce a custom TypeConverter for converting the
String "On(true)" into an instance of Toggle. The reason is that
org.apache.camel.impl.converter.EnumTypeConverter tries to call the
built-in valueOf(String) method which will end the program with a
RuntimeException:
Exception in thread "main" org.apache.camel.TypeConversionException:
Error during type conversion from type: java.lang.String to the
required type: EnumConversionExperiment.Toggle with value On(true)
due java.lang.IllegalAccessException: Class
org.apache.camel.util.ObjectHelper can not access a member of class
EnumConversionExperiment$Toggle with modifiers "public static"
at
org.apache.camel.impl.converter.BaseTypeConverterRegistry.createTypeConversionException(BaseTypeConverterRegistry.java:667)
at
org.apache.camel.impl.converter.BaseTypeConverterRegistry.convertTo(BaseTypeConverterRegistry.java:158)
at
org.apache.camel.impl.converter.BaseTypeConverterRegistry.convertTo(BaseTypeConverterRegistry.java:129)
at EnumConversionExperiment.main(EnumConversionExperiment.java:8)
Caused by: org.apache.camel.RuntimeCamelException:
java.lang.IllegalAccessException: Class
org.apache.camel.util.ObjectHelper can not access a member of class
EnumConversionExperiment$Toggle with modifiers "public static"
at
org.apache.camel.util.ObjectHelper.invokeMethod(ObjectHelper.java:1407)
at
org.apache.camel.impl.converter.EnumTypeConverter.convertTo(EnumTypeConverter.java:51)
at
org.apache.camel.impl.converter.OptimisedTypeConverter.convertTo(OptimisedTypeConverter.java:71)
at
org.apache.camel.impl.converter.BaseTypeConverterRegistry.doConvertTo(BaseTypeConverterRegistry.java:300)
at
org.apache.camel.impl.converter.BaseTypeConverterRegistry.convertTo(BaseTypeConverterRegistry.java:141)
... 2 more
Caused by: java.lang.IllegalAccessException: Class
org.apache.camel.util.ObjectHelper can not access a member of class
EnumConversionExperiment$Toggle with modifiers "public static"
at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102)
at
java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:296)
at
java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:288)
at java.lang.reflect.Method.invoke(Method.java:491)
at
org.apache.camel.util.ObjectHelper.invokeMethod(ObjectHelper.java:1405)
... 6 more
The type conversion process stops here instead of looking for custom
type converters. Line 53: return null; of EnumTypeConverter is never
reached. Would EnumTypeConverter indeed return null, the process would
continue and a custom converter would finally be called.
I'm pretty sure this is an issue. What do you think?
Regards,
Ralf
