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Merge pull request #702 from Netflix/custom-converters
Add a Decoder that accepts custom TypeConverters
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129
archaius2-core/src/main/java/com/netflix/archaius/AbstractRegistryDecoder.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,129 @@ | ||
| package com.netflix.archaius; | ||
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| import com.netflix.archaius.api.Decoder; | ||
| import com.netflix.archaius.api.TypeConverter; | ||
| import com.netflix.archaius.exceptions.ParseException; | ||
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| import java.lang.reflect.Constructor; | ||
| import java.lang.reflect.Method; | ||
| import java.lang.reflect.Type; | ||
| import java.util.ArrayList; | ||
| import java.util.Collection; | ||
| import java.util.Collections; | ||
| import java.util.List; | ||
| import java.util.Map; | ||
| import java.util.Optional; | ||
| import java.util.concurrent.ConcurrentHashMap; | ||
| import java.util.stream.Stream; | ||
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| /** | ||
| * A {@code Decoder} implementation that also implements {@code TypeConverter.Registry}, and delegates to a supplied | ||
| * collection of converter factories. | ||
| */ | ||
| abstract class AbstractRegistryDecoder implements Decoder, TypeConverter.Registry { | ||
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| private final Map<Type, TypeConverter<?>> cache = new ConcurrentHashMap<>(); | ||
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| private final List<TypeConverter.Factory> factories; | ||
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| AbstractRegistryDecoder(Collection<? extends TypeConverter.Factory> factories) { | ||
| this.factories = Collections.unmodifiableList(new ArrayList<>(factories)); | ||
| } | ||
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| @Override | ||
| public <T> T decode(Class<T> type, String encoded) { | ||
| return decode((Type) type, encoded); | ||
| } | ||
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| @Override | ||
| public <T> T decode(Type type, String encoded) { | ||
| try { | ||
| if (encoded == null) { | ||
| return null; | ||
| } | ||
| @SuppressWarnings("unchecked") | ||
| TypeConverter<T> converter = (TypeConverter<T>) getOrCreateConverter(type); | ||
| if (converter == null) { | ||
| throw new RuntimeException("No converter found for type '" + type + "'"); | ||
| } | ||
| return converter.convert(encoded); | ||
| } catch (Exception e) { | ||
| throw new ParseException("Error decoding type `" + type.getTypeName() + "`", e); | ||
| } | ||
| } | ||
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| @Override | ||
| public Optional<TypeConverter<?>> get(Type type) { | ||
| return Optional.ofNullable(getOrCreateConverter(type)); | ||
| } | ||
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| private TypeConverter<?> getOrCreateConverter(Type type) { | ||
| TypeConverter<?> converter = cache.get(type); | ||
| if (converter == null) { | ||
| converter = resolve(type); | ||
| if (converter == null) { | ||
| return null; | ||
| } | ||
| TypeConverter<?> existing = cache.putIfAbsent(type, converter); | ||
| if (existing != null) { | ||
| converter = existing; | ||
| } | ||
| } | ||
| return converter; | ||
| } | ||
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| /** | ||
| * Iterate through all TypeConverter#Factory's and return the first TypeConverter that matches | ||
| * @param type | ||
| * @return | ||
| */ | ||
| private TypeConverter<?> resolve(Type type) { | ||
| return factories.stream() | ||
| .flatMap(factory -> factory.get(type, this).map(Stream::of).orElseGet(Stream::empty)) | ||
| .findFirst() | ||
| .orElseGet(() -> findValueOfTypeConverter(type)); | ||
| } | ||
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| /** | ||
| * @param type | ||
| * @param <T> | ||
| * @return Return a converter that uses reflection on either a static valueOf or ctor(String) to convert a string value to the | ||
| * type. Will return null if neither is found | ||
| */ | ||
| private static <T> TypeConverter<T> findValueOfTypeConverter(Type type) { | ||
| if (!(type instanceof Class)) { | ||
| return null; | ||
| } | ||
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| @SuppressWarnings("unchecked") | ||
| Class<T> cls = (Class<T>) type; | ||
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| // Next look a valueOf(String) static method | ||
| Method method; | ||
| try { | ||
| method = cls.getMethod("valueOf", String.class); | ||
| return value -> { | ||
| try { | ||
| return (T) method.invoke(null, value); | ||
| } catch (Exception e) { | ||
| throw new ParseException("Error converting value '" + value + "' to '" + type.getTypeName() + "'", e); | ||
| } | ||
| }; | ||
| } catch (NoSuchMethodException e1) { | ||
| // Next look for a T(String) constructor | ||
| Constructor<T> c; | ||
| try { | ||
| c = cls.getConstructor(String.class); | ||
| return value -> { | ||
| try { | ||
| return (T) c.newInstance(value); | ||
| } catch (Exception e) { | ||
| throw new ParseException("Error converting value", e); | ||
| } | ||
| }; | ||
| } catch (NoSuchMethodException e) { | ||
| return null; | ||
| } | ||
| } | ||
| } | ||
| } |
33 changes: 33 additions & 0 deletions
33
archaius2-core/src/main/java/com/netflix/archaius/CustomDecoder.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,33 @@ | ||
| package com.netflix.archaius; | ||
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| import com.netflix.archaius.api.TypeConverter; | ||
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| import java.util.ArrayList; | ||
| import java.util.Collection; | ||
| import java.util.List; | ||
| import java.util.Objects; | ||
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| /** | ||
| * A configurable {@code Decoder} implementation which allows extension through custom {@code TypeConverter.Factory} | ||
| * instances. The custom factories are searched first, and if no appropriate converter is found, the default | ||
| * converters used by {@code DefaultDecoder} will be consulted. | ||
| */ | ||
| public class CustomDecoder extends AbstractRegistryDecoder { | ||
| private CustomDecoder(Collection<? extends TypeConverter.Factory> typeConverterFactories) { | ||
| super(typeConverterFactories); | ||
| } | ||
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| /** | ||
| * Create a new {@code CustomDecoder} with the supplied {@code TypeConverter.Factory} instances installed. | ||
| * The default converter factories will still be registered, but will be installed AFTER any custom ones, | ||
| * giving callers the opportunity to override the behavior of the default converters. | ||
| * | ||
| * @param customTypeConverterFactories the collection of converter factories to use for this decoder | ||
| */ | ||
| public static CustomDecoder create(Collection<? extends TypeConverter.Factory> customTypeConverterFactories) { | ||
| Objects.requireNonNull(customTypeConverterFactories, "customTypeConverterFactories == null"); | ||
| List<TypeConverter.Factory> factories = new ArrayList<>(customTypeConverterFactories); | ||
| factories.addAll(DefaultDecoder.DEFAULT_FACTORIES); | ||
| return new CustomDecoder(factories); | ||
| } | ||
| } |
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33 changes: 33 additions & 0 deletions
33
archaius2-core/src/test/java/com/netflix/archaius/CustomDecoderTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,33 @@ | ||
| package com.netflix.archaius; | ||
|
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| import com.netflix.archaius.api.TypeConverter; | ||
| import org.junit.Assert; | ||
| import org.junit.Test; | ||
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| import java.lang.reflect.Type; | ||
| import java.util.Collections; | ||
| import java.util.Optional; | ||
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| public class CustomDecoderTest { | ||
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| @Test | ||
| public void testCustomTypeConverters() { | ||
| TypeConverter<String> stringConverter = String::toUpperCase; | ||
| TypeConverter<Long> longConverter = value -> Long.parseLong(value) * 2; | ||
| TypeConverter.Factory factory = (type, registry) -> { | ||
| if ((type instanceof Class<?> && ((Class<?>) type).isAssignableFrom(String.class))) { | ||
| return Optional.of(stringConverter); | ||
| } else if (type.equals(Long.class)) { // override default converter | ||
| return Optional.of(longConverter); | ||
| } | ||
| return Optional.empty(); | ||
| }; | ||
| CustomDecoder decoder = CustomDecoder.create(Collections.singletonList(factory)); | ||
| Assert.assertEquals("FOO", decoder.decode((Type) CharSequence.class, "foo")); | ||
| Assert.assertEquals("FOO", decoder.decode((Type) String.class, "foo")); | ||
| // default is overridden | ||
| Assert.assertEquals(Long.valueOf(6), decoder.decode((Type) Long.class, "3")); | ||
| // default converter is used | ||
| Assert.assertEquals(Integer.valueOf(3), decoder.decode((Type) Integer.class, "3")); | ||
| } | ||
| } |
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