1 files changed, 97 insertions, 0 deletions
diff --git a/eaaf_core_utils/src/main/java/at/gv/egiz/eaaf/core/impl/json/EscapedJsonDeserializer.java b/eaaf_core_utils/src/main/java/at/gv/egiz/eaaf/core/impl/json/EscapedJsonDeserializer.java
new file mode 100644
index 00000000..5a081ec5
--- /dev/null
+++ b/eaaf_core_utils/src/main/java/at/gv/egiz/eaaf/core/impl/json/EscapedJsonDeserializer.java
@@ -0,0 +1,97 @@
+package at.gv.egiz.eaaf.core.impl.json;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.TreeNode;
+import com.fasterxml.jackson.databind.BeanProperty;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.JsonDeserializer;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.deser.ContextualDeserializer;
+import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+
+/**
+ * Custom Jackson Deserializer to support generic types serialized as escaped
+ * Strings.
+ * 
+ * <p>
+ * Code was an example from stack-overflow. <br>
+ * <br>
+ * This implementation checks if the generic class type is compatible to
+ * original interface, by using <code>Class.isAssignableFrom(...).</code>
+ * </p>
+ * 
+ * @author tlenz
+ *
+ */
+public class EscapedJsonDeserializer extends JsonDeserializer<Object> implements ContextualDeserializer {
+  private final Map<JavaType, JsonDeserializer<Object>> cachedDeserializers = new HashMap<>();
+
+  @Override
+  public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOException,
+      JsonProcessingException {
+    throw new IllegalArgumentException(
+        "EscapedJsonDeserializer should delegate deserialization for concrete class");
+
+  }
+
+  @Override
+  public JsonDeserializer<?> createContextual(DeserializationContext ctxt, BeanProperty property)
+      throws JsonMappingException {
+    JavaType type = (ctxt.getContextualType() != null) ? ctxt.getContextualType()
+        : property.getMember().getType();
+    return cachedDeserializers.computeIfAbsent(type, (a) -> new InnerDeserializer(type));
+  }
+
+  private static class InnerDeserializer extends JsonDeserializer<Object> {
+    private final JavaType javaType;
+
+    private InnerDeserializer(JavaType javaType) {
+      this.javaType = javaType;
+    }
+
+    @Override
+    public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOException,
+        JsonProcessingException {
+      String string = p.readValueAs(String.class);
+      return ((ObjectMapper) p.getCodec()).readValue(string, javaType);
+    }
+
+    @Override
+    public Object deserializeWithType(JsonParser p, DeserializationContext ctxt,
+        TypeDeserializer typeDeserializer)
+        throws IOException {
+      String str = p.readValueAs(String.class);
+      TreeNode root = ((ObjectMapper) p.getCodec()).readTree(str);
+      try {
+        Class clz = Class.forName(((TextNode) root.get("@class")).asText());
+
+        if (this.javaType.getRawClass().isAssignableFrom(clz)) {
+          // remove '@class' before deserialization because it's unknown in target class
+          if (root.isObject()) {
+            ((ObjectNode) root).remove("@class");
+          }
+
+          Object newJsonNode = p.getCodec().treeToValue(root, clz);
+          return newJsonNode;
+
+        } else {
+          throw new RuntimeException("Class looks supect because it does not match to interface.");
+
+        }
+
+      } catch (ClassNotFoundException e) {
+        throw new RuntimeException(e);
+
+      }
+    }
+  }
+}