Created
July 28, 2016 02:24
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| package com.google.gson.functional; | |
| import com.google.gson.Gson; | |
| import com.google.gson.GsonBuilder; | |
| import com.google.gson.TypeAdapter; | |
| import com.google.gson.TypeAdapterFactory; | |
| import com.google.gson.reflect.TypeToken; | |
| import com.google.gson.stream.JsonReader; | |
| import com.google.gson.stream.JsonWriter; | |
| import java.io.IOException; | |
| import java.lang.reflect.InvocationTargetException; | |
| import java.lang.reflect.Method; | |
| import javax.annotation.PostConstruct; | |
| import junit.framework.TestCase; | |
| public class PostConstructTest extends TestCase { | |
| public void test() throws Exception { | |
| Gson gson = new GsonBuilder() | |
| .registerTypeAdapterFactory(new PostConstructFactory()) | |
| .create(); | |
| gson.fromJson("{\"bread\": \"white\", \"cheese\": \"cheddar\"}", Sandwich.class); | |
| gson.fromJson("{\"bread\": \"cheesey bread\", \"cheese\": \"swiss\"}", Sandwich.class); | |
| } | |
| static class Sandwich { | |
| String bread; | |
| String cheese; | |
| @PostConstruct void validate() { | |
| if (bread.equals("cheesey bread") && cheese != null) { | |
| throw new IllegalArgumentException("too cheesey"); | |
| } | |
| } | |
| } | |
| static class PostConstructFactory implements TypeAdapterFactory { | |
| @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) { | |
| for (Class<?> t = type.getRawType(); t != Object.class; t = t.getSuperclass()) { | |
| for (Method m : t.getDeclaredMethods()) { | |
| if (m.isAnnotationPresent(PostConstruct.class)) { | |
| m.setAccessible(true); | |
| TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type); | |
| return new PostConstructAdapter<T>(delegate, m); | |
| } | |
| } | |
| } | |
| return null; | |
| } | |
| } | |
| static class PostConstructAdapter<T> extends TypeAdapter<T> { | |
| private final TypeAdapter<T> delegate; | |
| private final Method method; | |
| public PostConstructAdapter(TypeAdapter<T> delegate, Method method) { | |
| this.delegate = delegate; | |
| this.method = method; | |
| } | |
| @Override public T read(JsonReader in) throws IOException { | |
| T result = delegate.read(in); | |
| if (result != null) { | |
| try { | |
| method.invoke(result); | |
| } catch (IllegalAccessException e) { | |
| throw new AssertionError(); | |
| } catch (InvocationTargetException e) { | |
| if (e.getCause() instanceof RuntimeException) throw (RuntimeException) e.getCause(); | |
| throw new RuntimeException(e.getCause()); | |
| } | |
| } | |
| return result; | |
| } | |
| @Override public void write(JsonWriter out, T value) throws IOException { | |
| delegate.write(out, value); | |
| } | |
| } | |
| } |
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