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src/main/java/io/foldright/inspectablewrappers/utils/WrapperAdapterUtils.java
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| @@ -0,0 +1,120 @@ | ||
| package io.foldright.inspectablewrappers.utils; | ||
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| import edu.umd.cs.findbugs.annotations.NonNull; | ||
| import edu.umd.cs.findbugs.annotations.Nullable; | ||
| import io.foldright.inspectablewrappers.Attachable; | ||
| import io.foldright.inspectablewrappers.Wrapper; | ||
| import io.foldright.inspectablewrappers.WrapperAdapter; | ||
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| import java.lang.reflect.InvocationHandler; | ||
| import java.lang.reflect.Method; | ||
| import java.lang.reflect.Proxy; | ||
| import java.util.Arrays; | ||
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| import static java.util.Objects.requireNonNull; | ||
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| /** | ||
| * Utility class for creating {@link WrapperAdapter} instances | ||
| * without writing boilerplate code of creating a new adapter class. | ||
| * | ||
| * @author Jerry Lee (oldratlee at gmail dot com) | ||
| */ | ||
| public final class WrapperAdapterUtils { | ||
| /** | ||
| * Creates a {@link WrapperAdapter} instance of the given biz interface type | ||
| * by the adapted/existed wrapper instance and the underlying instance that be wrapped. | ||
| * | ||
| * @param <T> the type of instances that be wrapped | ||
| * @param bizInterface the class of instances that be wrapped | ||
| * @param underlying the underlying instance that be wrapped, more info see {@link Wrapper#unwrap()} | ||
| * @param adaptee the adapted/existed wrapper instance, more info see {@link WrapperAdapter#adaptee()} | ||
| * @return the new {@link WrapperAdapter} instance | ||
| * @see Wrapper#unwrap() | ||
| * @see WrapperAdapter#adaptee() | ||
| */ | ||
| @NonNull | ||
| public static <T> T createWrapperAdapter(Class<T> bizInterface, T underlying, T adaptee) { | ||
| return createWrapperAdapter0( | ||
| requireNonNull(bizInterface, "bizInterface is null"), | ||
| requireNonNull(underlying, "underlying is null"), | ||
| requireNonNull(adaptee, "adaptee is null"), | ||
| null); | ||
| } | ||
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| /** | ||
| * Creates a {@link WrapperAdapter} instance of the given biz interface type with attachable interface | ||
| * by the adapted/existed wrapper instance, the underlying instance that be wrapped and an attachable instance. | ||
| * | ||
| * @param <T> the type of instances that be wrapped | ||
| * @param bizInterface the class of instances that be wrapped | ||
| * @param underlying the underlying instance that be wrapped, more info see {@link Wrapper#unwrap()} | ||
| * @param adaptee the adapted/existed wrapper instance, more info see {@link WrapperAdapter#adaptee()} | ||
| * @param attachable the attachable instance, more info see {@link Attachable} | ||
| * @return the new {@link WrapperAdapter} instance | ||
| * @see Wrapper#unwrap() | ||
| * @see WrapperAdapter#adaptee() | ||
| * @see Attachable#getAttachment(Object) | ||
| * @see Attachable#setAttachment(Object, Object) | ||
| */ | ||
| @NonNull | ||
| public static <T> T createWrapperAdapter(Class<T> bizInterface, T underlying, T adaptee, Attachable<?, ?> attachable) { | ||
| return createWrapperAdapter0( | ||
| requireNonNull(bizInterface, "bizInterface is null"), | ||
| requireNonNull(underlying, "underlying is null"), | ||
| requireNonNull(adaptee, "adaptee is null"), | ||
| requireNonNull(attachable, "attachable is null")); | ||
| } | ||
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| @SuppressWarnings({"unchecked", "rawtypes"}) | ||
| private static <T> T createWrapperAdapter0(Class<T> bizInterface, T underlying, T adaptee, @Nullable Attachable<?, ?> attachable) { | ||
| final InvocationHandler handler = (proxy, method, args) -> { | ||
| if (isMethodUnwrap(method)) return underlying; | ||
| if (isMethodAdaptee(method)) return adaptee; | ||
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| if (attachable != null && isMethodGetAttachment(method)) | ||
| return ((Attachable) attachable).getAttachment(args[0]); | ||
| if (attachable != null && isMethodSetAttachment(method)) { | ||
| ((Attachable) attachable).setAttachment(args[0], args[1]); | ||
| return null; | ||
| } | ||
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| return method.invoke(adaptee, args); | ||
| }; | ||
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| return (T) Proxy.newProxyInstance( | ||
| adaptee.getClass().getClassLoader(), | ||
| attachable == null | ||
| ? new Class[]{bizInterface, WrapperAdapter.class} | ||
| : new Class[]{bizInterface, WrapperAdapter.class, Attachable.class}, | ||
| handler); | ||
| } | ||
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| private static boolean isMethodAdaptee(Method method) { | ||
| return checkMethod(method, "adaptee"); | ||
| } | ||
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| private static boolean isMethodUnwrap(Method method) { | ||
| return checkMethod(method, "unwrap"); | ||
| } | ||
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| private static boolean isMethodGetAttachment(Method method) { | ||
| return checkMethod(method, "getAttachment", Object.class); | ||
| } | ||
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| private static boolean isMethodSetAttachment(Method method) { | ||
| return checkMethod(method, "setAttachment", Object.class, Object.class); | ||
| } | ||
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| private static boolean checkMethod(Method method, String methodName, Class<?>... parameterTypes) { | ||
| return method.getName().equals(methodName) | ||
| && method.getParameterCount() == parameterTypes.length | ||
| && Arrays.equals(method.getParameterTypes(), parameterTypes); | ||
| } | ||
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| /** | ||
| * NO need to create instance at all | ||
| */ | ||
| private WrapperAdapterUtils() { | ||
| } | ||
| } |
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