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JSON Rendering Engine

Hasor Web renders objects and collections as JSON and strings as text by default. null and void do not produce a default body. There is no need to configure a renderer, Content-Type, or filter in every Action.

@Get
public java.util.Map<String, Object> hello() {
    return java.util.Map.of("message", "Hello");
}

JSON library selection​

AutoJsonRenderEngine searches the application classpath in this order: Jackson 2, Gson, Fastjson 1, then Fastjson 2. The application must supply the library. Startup fails if default JSON rendering is selected but no library is available. A present but broken implementation reports an error rather than silently falling back. Default selection does not look up Gson or ObjectMapper Beans in the container.

Custom serialization​

Register a configured engine through WebMvcConfigurer.configureJson:

@Override
public void configureJson(net.hasor.config.web.render.JsonRenderConfigurer configurer) {
    com.google.gson.Gson gson = new com.google.gson.GsonBuilder().serializeNulls().create();
    configurer.renderEngine(new net.hasor.web.render.json.GsonRenderEngine(gson));
}

Other implementations support:

  • JacksonRenderEngine: ObjectMapper。
  • JsonRenderEngine: Fastjson 1 SerializeConfig and SerializerFeature.
  • Fastjson2RenderEngine: ObjectWriterProvider and JSONWriter.Feature, or Supplier<JSONWriter.Context>.

Context factories must return a separate instance on each call. Configure shared serialization objects before handling requests, and do not modify them during requests. These settings affect response serialization only, not request parameter binding.

renderEngine("name") only sets the name for subsequent registration; calling it alone does not switch the default engine. Instance, type, and Supplier overloads supply the actual engine. The MVC callback completes registration; do not call register() manually. Default selection is controlled by hasor.render.defaults.objectEngine and stringEngine.

For a fully custom implementation, implement RenderEngine and register it through binder.addRender("json").to(CustomJsonRenderEngine.class). Explicit registration overrides a configured fallback with the same name. See Default Rendering.