diff options
| -rw-r--r-- | pom.xml | 6 | ||||
| -rw-r--r-- | src/main/java/org/openslx/util/Json.java | 122 |
2 files changed, 128 insertions, 0 deletions
@@ -121,6 +121,12 @@ <version>0.0.3-SNAPSHOT</version> <scope>compile</scope> </dependency> + <dependency> + <groupId>com.google.code.gson</groupId> + <artifactId>gson</artifactId> + <version>2.2.4</version> + <scope>compile</scope> + </dependency> </dependencies> </project> diff --git a/src/main/java/org/openslx/util/Json.java b/src/main/java/org/openslx/util/Json.java new file mode 100644 index 0000000..847514d --- /dev/null +++ b/src/main/java/org/openslx/util/Json.java @@ -0,0 +1,122 @@ +package org.openslx.util; + +import java.lang.reflect.Field; +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; +import java.lang.reflect.Modifier; +import java.lang.reflect.Type; + +import org.apache.log4j.Logger; +import org.apache.thrift.TBase; + +import com.google.gson.Gson; +import com.google.gson.GsonBuilder; +import com.google.gson.JsonDeserializationContext; +import com.google.gson.JsonDeserializer; +import com.google.gson.JsonElement; +import com.google.gson.JsonObject; +import com.google.gson.JsonParseException; +import com.google.gson.JsonSyntaxException; + +public class Json { + + private static final Logger LOGGER = Logger.getLogger(Json.class); + + /** + * Global static instance. The Gson object is thread-safe. + */ + private static final Gson gson = new Gson(); + + private static final GsonBuilder gsonThriftBuilder = new GsonBuilder(); + + public static <T> void registerThriftClass(Class<T> thriftClass) { + if (!TBase.class.isAssignableFrom(thriftClass)) + throw new IllegalArgumentException(thriftClass.getName() + " is not a thrift struct."); + gsonThriftBuilder.registerTypeAdapter(thriftClass, new ThriftDeserializer<T>(thriftClass)); + } + + /** + * Deserialize the given json string to an instance of T. + * This will deserialize all fields, except transient ones. + * + * @param data JSON formatted data + * @param classOfData class to instantiate + * @return instanceof T + */ + public static <T> T deserialize(String data, Class<T> classOfData) { + try { + return gson.fromJson(data, classOfData); + } catch (JsonSyntaxException e) { + LOGGER.warn("Cannot deserialize to " + classOfData.getSimpleName(), e); + return null; + } + } + + public static <T> T deserializeThrift(String data, Class<T> thriftClass) { + try { + return gsonThriftBuilder.create().fromJson(data, thriftClass); + } catch (JsonSyntaxException e) { + LOGGER.warn("Cannot deserialize to " + thriftClass.getSimpleName(), e); + return null; + } + } + + /** + * Serialize the given POJO. All fields except transient ones will be + * serialized. + * + * @param object some object to serialize + * @return JSON formatted represenatation of <code>object</code> + */ + public static String serialize(Object object) { + return gson.toJson(object); + } + + private static class ThriftDeserializer<T> implements JsonDeserializer<T> { + private final Class<T> clazz; + + public ThriftDeserializer(Class<T> classOfData) { + this.clazz = classOfData; + } + + @Override + public T deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) + throws JsonParseException { + if (!(json instanceof JsonObject)) + throw new JsonParseException("Need a json object, have " + json.getClass().getSimpleName()); + JsonObject obj = (JsonObject) json; + final T inst; + try { + inst = clazz.newInstance(); + } catch (InstantiationException | IllegalAccessException e) { + LOGGER.warn("Could not deserialize to class " + clazz.getName(), e); + throw new JsonParseException("Cannot instantiate class " + clazz.getSimpleName()); + } + for (Field field : clazz.getFields()) { + if (Modifier.isStatic(field.getModifiers()) || Modifier.isFinal(field.getModifiers())) + continue; + final String methodName = "set" + field.getName().substring(0, 1).toUpperCase() + + field.getName().substring(1); + final Method setter; + try { + setter = clazz.getMethod(methodName, field.getType()); + } catch (NoSuchMethodException e) { + LOGGER.warn(clazz.getSimpleName() + " has no method " + methodName); + continue; + } + JsonElement element = obj.get(field.getName()); + if (element == null || element.isJsonNull()) + continue; + try { + setter.invoke(inst, context.deserialize(element, field.getType())); + LOGGER.info("Called " + methodName + " on " + clazz.getSimpleName()); + } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) { + LOGGER.warn("Could not call " + methodName + " on " + clazz.getSimpleName(), e); + } + } + return inst; + } + + } + +} |