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Improve the semantics of @Transform handling.

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@Transform is first sought on the field itself, which overrides any other
handling. Next it is sought on the class that represents the field (i.e. if the
field is type Foo we look for an @Transform annotation on class Foo). We avoid
doing this somewhat expensive search if the field has a type that we know
cannot have an @Transform annotation. If we've still found no @Transform
annotation (which is unfortunately the overwhelmingly common case), we then
create a stock marshaller.
This commit is contained in:
Michael Bayne
2012-04-13 16:00:46 +00:00
parent 385e823b5b
commit 6d8eabce93
1 changed files with 31 additions and 22 deletions
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src/main/java/com/samskivert/depot/impl/FieldMarshaller.java
+31 -22
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@@ -68,32 +68,41 @@ public abstract class FieldMarshaller<T>
// first, look for a @Transform annotation on the field (cheap)
Transform xform = field.getAnnotation(Transform.class);
if (xform == null) {
// next look for a marshaller for the basic type (cheapish)
FieldMarshaller<?> marshaller = createMarshaller(field.getType());
if (marshaller != null) {
marshaller.create(field);
return marshaller;
// next look for an @Transform annotation on the field type; we only do this if it's a
// non-primitive/non-string type because this search is somewhat expensive
Class<?> ftype = field.getType();
if (!ftype.isPrimitive() && !ftype.equals(String.class)) {
xform = findTransformAnnotation(field.getType());
}
// finally look for an @Transform annotation on the field type (expensive)
xform = findTransformAnnotation(field.getType());
checkArgument(xform != null, "Cannot marshall " + field + ".");
}
try {
// weirdly if we inline the xformer creation into the createTransformingMarshaller
// call, we get a type error; must be some subtlety of wildcard capture...
Transformer<?, ?> xformer = xform.value().newInstance();
return createTransformingMarshaller(xformer, field, xform);
} catch (InstantiationException e) {
throw new IllegalArgumentException(
Logger.format("Unable to create Transformer", "xclass", xform.value(),
"field", field), e);
} catch (IllegalAccessException e) {
throw new IllegalArgumentException(
Logger.format("Unable to create Transformer", "xclass", xform.value(),
"field", field), e);
// if we found a transform annotation, create a transforming marshaller
if (xform != null) {
try {
// weirdly if we inline the xformer creation into the createTransformingMarshaller
// call, we get a type error; must be some subtlety of wildcard capture...
Transformer<?, ?> xformer = xform.value().newInstance();
return createTransformingMarshaller(xformer, field, xform);
} catch (InstantiationException e) {
throw new IllegalArgumentException(
Logger.format("Unable to create Transformer", "xclass", xform.value(),
"field", field), e);
} catch (IllegalAccessException e) {
throw new IllegalArgumentException(
Logger.format("Unable to create Transformer", "xclass", xform.value(),
"field", field), e);
}
}
// last look for a marshaller for the basic type (cheapish)
FieldMarshaller<?> marshaller = createMarshaller(field.getType());
if (marshaller != null) {
marshaller.create(field);
return marshaller;
}
// at this point we must throw up our hands
throw new IllegalArgumentException("Cannot marshall " + field + ".");
}
protected static <F,T> FieldMarshaller<F> createTransformingMarshaller (