git.basschouten.com Git - openhab-addons.git/blob

   1 /*
   2  * Pulled from Stack Overflow answer located here: http://stackoverflow.com/a/11272452
   3  * and placed in an appropriate package within this library.
   4  */
   5 package org.openhab.binding.lametrictime.api.common.impl.typeadapters.imported;
   6
   7 import java.io.IOException;
   8 import java.io.ObjectStreamException;
   9
  10 import com.google.gson.Gson;
  11 import com.google.gson.JsonElement;
  12 import com.google.gson.TypeAdapter;
  13 import com.google.gson.TypeAdapterFactory;
  14 import com.google.gson.reflect.TypeToken;
  15 import com.google.gson.stream.JsonReader;
  16 import com.google.gson.stream.JsonWriter;
  17
  18 public abstract class CustomizedTypeAdapterFactory<C> implements TypeAdapterFactory
  19 {
  20     private final Class<C> customizedClass;
  21
  22     public CustomizedTypeAdapterFactory(Class<C> customizedClass)
  23     {
  24         this.customizedClass = customizedClass;
  25     }
  26
  27     @Override
  28     @SuppressWarnings("unchecked") // we use a runtime check to guarantee that 'C' and 'T' are equal
  29     public final <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type)
  30     {
  31         return type.getRawType() == customizedClass
  32                 ? (TypeAdapter<T>)customizeMyClassAdapter(gson, (TypeToken<C>)type)
  33                 : null;
  34     }
  35
  36     private TypeAdapter<C> customizeMyClassAdapter(Gson gson, TypeToken<C> type)
  37     {
  38         final TypeAdapter<C> delegate = gson.getDelegateAdapter(this, type);
  39         final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
  40         return new TypeAdapter<C>()
  41         {
  42             @Override
  43             public void write(JsonWriter out, C value) throws IOException
  44             {
  45                 JsonElement tree = delegate.toJsonTree(value);
  46                 beforeWrite(value, tree);
  47                 elementAdapter.write(out, tree);
  48             }
  49
  50             @Override
  51             public C read(JsonReader in) throws IOException
  52             {
  53                 JsonElement tree = elementAdapter.read(in);
  54                 afterRead(tree);
  55                 if (tree == null) {
  56                     throw new IOException("null reader");
  57                 }
  58                 return delegate.fromJsonTree(tree);
  59             }
  60         };
  61     }
  62
  63     /**
  64      * Override this to muck with {@code toSerialize} before it is written to
  65      * the outgoing JSON stream.
  66      */
  67     protected void beforeWrite(C source, JsonElement toSerialize)
  68     {
  69     }
  70
  71     /**
  72      * Override this to muck with {@code deserialized} before it parsed into the
  73      * application type.
  74      */
  75     protected void afterRead(JsonElement deserialized)
  76     {
  77     }
  78 }