无法使用jackson反序列化java.awt.color

Question

  public class TestJacksonColor {
        public static void main(String [] args) throws IOException {
            ObjectMapper objectMapper = new ObjectMapper();
            Color black = new Color(0, 0, 0);
            String json = objectMapper.writeValueAsString(black);
            Color backToObject = objectMapper.readValue(json, Color.class);
        }
    }

代码试图采用java.awt.color类使用jackson对象映射器对其进行序列化。获取生成的json字符串并将其反序列化回java.awt.color类。但是在进行反序列化时会出现以下错误。

线程"main"com.fasterxml.jackson.databind.JsonMappingException中的异常：找不到适合类型[简单类型，类java.awt.颜色]的构造函数：无法从JSON对象实例化

Answer 1

您需要一个自定义序列化器和反序列化器。周围有一些预构建的模块，但我不知道有一个处理java.awt.Color的模块。

这是一个定义序列化器/反序列化器对并注册一个模块来处理Color对象的示例：

public class JacksonColorTest {

    public static class ColorSerializer extends JsonSerializer<Color> {
        @Override
        public void serialize(Color value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
            gen.writeStartObject();
            gen.writeFieldName("argb");
            gen.writeString(Integer.toHexString(value.getRGB()));
            gen.writeEndObject();
        }
    }

    public static class ColorDeserializer extends JsonDeserializer<Color> {
        @Override
        public Color deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
            TreeNode root = p.getCodec().readTree(p);
            TextNode rgba = (TextNode) root.get("argb");
            return new Color(Integer.parseUnsignedInt(rgba.textValue(), 16), true);
        }
    }

    public static void main(String [] args) throws IOException {
        ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addSerializer(Color.class, new ColorSerializer());
        module.addDeserializer(Color.class, new ColorDeserializer());
        objectMapper.registerModule(module);

        Color testColor = new Color(1, 2, 3, 4);
        String json = objectMapper.writeValueAsString(testColor);
        Color backToObject = objectMapper.readValue(json, Color.class);

        if (!testColor.equals(backToObject)) {
            throw new AssertionError("round trip failed");
        }
    }
}