[json-core] SimpleMapper add type support for customer JsonAdapters (#…

…310)

For cases where we want to manually build a JsonAdapter and then use that via SimpleMapper

json-core/src/main/java/io/avaje/json/simple/DSimpleMapper.java

@@ -1,5 +1,6 @@
 package io.avaje.json.simple;
 
+import io.avaje.json.JsonAdapter;
 import io.avaje.json.core.CoreTypes;
 import io.avaje.json.stream.JsonStream;
 
@@ -8,16 +9,23 @@
 
 final class DSimpleMapper implements SimpleMapper {
 
+  private final JsonStream jsonStream;
   private final Type<Object> objectType;
   private final Type<Map<String,Object>> mapType;
   private final Type<List<Object>> listType;
 
   DSimpleMapper(JsonStream jsonStream, CoreTypes.CoreAdapters adapters) {
+    this.jsonStream = jsonStream;
     this.objectType = new DTypeMapper<>(adapters.objectAdapter(), jsonStream);
     this.mapType = new DTypeMapper<>(adapters.mapAdapter(), jsonStream);
     this.listType = new DTypeMapper<>(adapters.listAdapter(), jsonStream);
   }
 
+  @Override
+  public <T> Type<T> type(JsonAdapter<T> myAdapter) {
+    return new DTypeMapper<>(myAdapter, jsonStream);
+  }
+
   @Override
   public Type<Object> object() {
     return objectType;

json-core/src/main/java/io/avaje/json/simple/SimpleMapper.java

@@ -1,5 +1,6 @@
 package io.avaje.json.simple;
 
+import io.avaje.json.JsonAdapter;
 import io.avaje.json.JsonReader;
 import io.avaje.json.JsonWriter;
 import io.avaje.json.stream.JsonStream;
@@ -56,6 +57,15 @@ static Builder builder() {
    */
   Type<List<Object>> list();
 
+  /**
+   * Return a Type specific mapper for the given JsonAdapter.
+   *
+   * @param customAdapter The custom adapter to use.
+   * @param <T>           The type of the class to map to/from json.
+   * @return The Type specific mapper.
+   */
+  <T> Type<T> type(JsonAdapter<T> customAdapter);
+
   /**
    * Write the object to JSON string.
    * <p>

json-core/src/test/java/io/avaje/json/simple/CustomAdapter2Test.java

@@ -0,0 +1,73 @@
+package io.avaje.json.simple;
+
+import io.avaje.json.JsonAdapter;
+import io.avaje.json.JsonReader;
+import io.avaje.json.JsonWriter;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class CustomAdapter2Test {
+
+  static final SimpleMapper simpleMapper = SimpleMapper.builder().build();
+
+  @Test
+  void mapUsingCustomAdapter() {
+
+    MyAdapterUsingRaw myAdapter = new MyAdapterUsingRaw();
+
+    SimpleMapper.Type<MyOtherType> type = simpleMapper.type(myAdapter);
+
+    MyOtherType source = new MyOtherType();
+    source.foo = "hi";
+    source.bar = 42;
+    String asJson = type.toJson(source);
+
+    MyOtherType fromJson = type.fromJson(asJson);
+
+    assertThat(fromJson.foo).isEqualTo(source.foo);
+    assertThat(fromJson.bar).isEqualTo(source.bar);
+  }
+
+  static class MyOtherType {
+    String foo;
+    int bar;
+  }
+
+  static class MyAdapterUsingRaw implements JsonAdapter<MyOtherType> {
+
+    @Override
+    public void toJson(JsonWriter writer, MyOtherType value) {
+      writer.beginObject();
+      writer.name("foo");
+      writer.value(value.foo);
+      writer.name("bar");
+      writer.value(value.bar);
+      writer.endObject();
+    }
+
+    @Override
+    public MyOtherType fromJson(JsonReader reader) {
+      MyOtherType result = new MyOtherType();
+
+      reader.beginObject();
+
+      String key;
+      while (reader.hasNextField()) {
+        key = reader.nextField();
+        switch (key) {
+          case "foo":
+            result.foo = reader.readString();
+            break;
+          case "bar":
+            result.bar = reader.readInt();
+            break;
+          default:
+            reader.skipValue();
+        }
+      }
+      reader.endObject();
+      return result;
+    }
+  }
+}

json-core/src/test/java/io/avaje/json/simple/CustomAdapterTest.java

@@ -0,0 +1,63 @@
+package io.avaje.json.simple;
+
+import io.avaje.json.JsonAdapter;
+import io.avaje.json.JsonReader;
+import io.avaje.json.JsonWriter;
+import org.junit.jupiter.api.Test;
+
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class CustomAdapterTest {
+
+  static final SimpleMapper simpleMapper = SimpleMapper.builder().build();
+
+  @Test
+  void mapUsingCustomAdapter() {
+
+    MyAdapter myAdapter = new MyAdapter(simpleMapper);
+
+    SimpleMapper.Type<MyCustomType> type = simpleMapper.type(myAdapter);
+
+    MyCustomType source = new MyCustomType();
+    source.foo = "hi";
+    source.bar = 42;
+    String asJson = type.toJson(source);
+
+    MyCustomType fromJson = type.fromJson(asJson);
+
+    assertThat(fromJson.foo).isEqualTo(source.foo);
+    assertThat(fromJson.bar).isEqualTo(source.bar);
+  }
+
+  static class MyCustomType {
+    public String foo;
+    public int bar;
+  }
+
+  static class MyAdapter implements JsonAdapter<MyCustomType> {
+
+    private final SimpleMapper.Type<Map<String, Object>> map;
+
+    public MyAdapter(SimpleMapper simpleMapper) {
+      this.map = simpleMapper.map();
+    }
+
+    @Override
+    public void toJson(JsonWriter writer, MyCustomType value) {
+      Map<String, Object> foo = Map.of("foo", value.foo, "bar", value.bar);
+      map.toJson(foo, writer);
+    }
+
+    @Override
+    public MyCustomType fromJson(JsonReader reader) {
+      Map<String, Object> mapValue = map.fromJson(reader);
+      MyCustomType myCustomType = new MyCustomType();
+      myCustomType.foo = (String)mapValue.get("foo");
+      Number bar = (Number)mapValue.get("bar");
+      myCustomType.bar = bar == null ? 0 : bar.intValue();
+      return myCustomType;
+    }
+  }
+}