这不是理想的解决方案。请参阅我的第二个答案。
我使用ModelAndViewResolver. 您可以直接使用 注册这些，并且AnnotationMethodHandlerAdapter知道它们总是在默认处理发生之前首先启动。因此，Spring的文档 -
/**
* Set a custom ModelAndViewResolvers to use for special method return types.
* <p>Such a custom ModelAndViewResolver will kick in first, having a chance to resolve
* a return value before the standard ModelAndView handling kicks in.
*/
public void setCustomModelAndViewResolver(ModelAndViewResolver customModelAndViewResolver) {
this.customModelAndViewResolvers = new ModelAndViewResolver[] {customModelAndViewResolver};
}
查看ModelAndViewResolver接口，我知道它包含将某些功能扩展到处理程序方法的工作方式所需的所有参数。
public interface ModelAndViewResolver {
ModelAndView UNRESOLVED = new ModelAndView();
ModelAndView resolveModelAndView(Method handlerMethod,
Class handlerType,
Object returnValue,
ExtendedModelMap implicitModel,
NativeWebRequest webRequest);
}
看看所有那些美味的论点resolveModelAndView！我几乎可以访问 Spring 知道的关于请求的所有内容。以下是我实现接口的MappingJacksonHttpMessageConverter方式，以单向方式（向外）与除了非常相似的行为：
public class JsonModelAndViewResolver implements ModelAndViewResolver {
public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
public static final MediaType DEFAULT_MEDIA_TYPE = new MediaType("application", "json", DEFAULT_CHARSET);
private boolean prefixJson = false;
public void setPrefixJson(boolean prefixJson) {
this.prefixJson = prefixJson;
}
/**
* Converts Json.mixins() to a Map<Class, Class>
*
* @param jsonFilter Json annotation
* @return Map of Target -> Mixin classes
*/
protected Map<Class<?>, Class<?>> getMixins(Json jsonFilter) {
Map<Class<?>, Class<?>> mixins = new HashMap<Class<?>, Class<?>>();
if(jsonFilter != null) {
for(JsonMixin jsonMixin : jsonFilter.mixins()) {
mixins.put(jsonMixin.target(), jsonMixin.mixin());
}
}
return mixins;
}
@Override
public ModelAndView resolveModelAndView(Method handlerMethod, Class handlerType, Object returnValue, ExtendedModelMap implicitModel, NativeWebRequest webRequest) {
if(handlerMethod.getAnnotation(Json.class) != null) {
try {
HttpServletResponse httpResponse = webRequest.getNativeResponse(HttpServletResponse.class);
httpResponse.setContentType(DEFAULT_MEDIA_TYPE.toString());
OutputStream out = httpResponse.getOutputStream();
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.setMixInAnnotations(getMixins(handlerMethod.getAnnotation(Json.class)));
JsonGenerator jsonGenerator =
objectMapper.getJsonFactory().createJsonGenerator(out, JsonEncoding.UTF8);
if (this.prefixJson) {
jsonGenerator.writeRaw("{} && ");
}
objectMapper.writeValue(jsonGenerator, returnValue);
out.flush();
out.close();
return null;
} catch (JsonProcessingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
return UNRESOLVED;
}
}
上面使用的唯一自定义类是我的注释类@Json，其中包含一个名为mixins. 这是我在控制器端实现它的方法。
@Controller
public class Controller {
@Json({ @JsonMixin(target=MyTargetObject.class, mixin=MyTargetMixin.class) })
@RequestMapping(value="/my-rest/{id}/my-obj", method=RequestMethod.GET)
public @ResponseBody List<MyTargetObject> getListOfFoo(@PathVariable("id") Integer id) {
return MyServiceImpl.getInstance().getBarObj(id).getFoos();
}
}
这是一些非常棒的简单性。ModelAndViewResolver 将自动将返回对象转换为 JSON 并应用带注释的 mix-ins。
由于新的 3.0 标签不允许直接配置 ModelAndViewResolver。也许他们只是忽略了这一点？
我的旧配置（使用 Spring 3.1 样式）
<mvc:annotation-driven />
我的新配置（使用 Spring 2.5 风格）
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
<property name="customModelAndViewResolvers">
<list>
<bean class="my.package.mvc.JsonModelAndViewResolver" />
</list>
</property>
</bean>
^^ 3.0+ 无法连接自定义 ModelAndViewResolver。因此，切换回旧样式。
这是自定义注释：
json
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface Json {
/**
* A list of Jackson Mixins.
* <p>
* {@link http://wiki.fasterxml.com/JacksonMixInAnnotations}
*/
JsonMixin[] mixins() default {};
}
JsonMixin
public @interface JsonMixin {
public Class<? extends Serializable> target();
public Class<?> mixin();
}