摘要：前言和切面一樣，在項目中同樣使用了自定義注解，目前項目中使用的自定義注解主要分為以下一些方面參數解析，緩存方法聲明，導入功能中的聲明。

和切面一樣，在項目中同樣使用了自定義注解，目前項目中使用的自定義注解主要分為以下一些方面：controller參數解析，緩存方法聲明，導入功能中的POJO聲明。

用在controller的方法參數，解析前臺提交的json參數，組裝成java對象。用法如下：

    @PostMapping("/bas/user/status/toggle")
    public PackVo toggleUserStatus(@JsonObject Long[] userIds , @JsonObject Long status ){
        ... 
    }

注解聲明

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface JsonObject {
    String value() default "";
    boolean required() default true;
}

注解處理,實現HandlerMethodArgumentResolver，

public class JsonArgumentResolver implements HandlerMethodArgumentResolver {
    public static Logger logger = LoggerFactory.getLogger(JsonArgumentResolver.class);

    @Override
    public boolean supportsParameter(MethodParameter methodParameter) {
        return methodParameter.hasParameterAnnotation(JsonObject.class);
    }

    @Override
    public Object resolveArgument(MethodParameter methodParameter, ModelAndViewContainer modelAndViewContainer, NativeWebRequest nativeWebRequest, WebDataBinderFactory webDataBinderFactory)
            throws Exception {
        try {
            JSONObject para = getRequestInfo(nativeWebRequest);
            Class type = methodParameter.getParameterType();
            String name = methodParameter.getParameterName();
            //獲取參數注解JsonObject,如果為空，則使用參數名，不為空，則使用注解中的value
            Annotation[] annotations = methodParameter.getParameterAnnotations();
            for(Annotation annotation : annotations){
                if(annotation instanceof JsonObject){
                    String value = ((JsonObject) annotation).value();
                    if(StringUtils.isNotEmpty(value)){
                        name = value;
                    }
                }
            }
            if (null != para && para.containsKey(name)) {
                if (String.class.equals(type)) {
                    return para.getString(name);
                }
                if (List.class.equals(type)) {
                    String typeName = methodParameter.getGenericParameterType().getTypeName();
                    typeName = typeName.substring(typeName.indexOf("<")+1);
                    typeName =typeName.substring(0,typeName.length()-1);

                    return JSON.parseArray(para.getString(name), Class.forName(typeName));

                }
                return JSON.parseObject(para.getString(name), type);
            }
        } catch (Exception e) {
            e.printStackTrace();
            logger.info("",e);
        }
        return null;
    }
    private JSONObject getRequestInfo(NativeWebRequest webRequest) throws IOException {
        JSONObject para = new JSONObject();
        HttpServletRequest httpServletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
        String method = httpServletRequest.getMethod();
        if (!method.equals("GET") && !method.equals("DELETE")) {

            if (null != httpServletRequest.getAttribute("para")) {
                try {
                    para = JSON.parseObject(httpServletRequest.getAttribute("para").toString());
                } catch (Exception e) {
                    e.printStackTrace();
                    logger.info("",e);
                }
            } else {
                StringBuilder buffer = new StringBuilder();
                BufferedReader reader = httpServletRequest.getReader();
                String line;
                while ((line = reader.readLine()) != null) {
                    buffer.append(line);
                }
                httpServletRequest.setAttribute("para", buffer.toString());

                try {
                    para = JSON.parseObject(buffer.toString());
                } catch (Exception e) {
                    e.printStackTrace();
                    logger.info("",e);
                }
            }
        } else {
            Map parameterMap = webRequest.getParameterMap();
            for (Map.Entry entry : parameterMap.entrySet()) {
                String key = entry.getKey();
                String values = StringUtils.join(entry.getValue());
                para.put(key, values);
            }
        }
        return para;
    }

}

接口使用方式如下：

注解聲明，具體的注解處理在上一篇的DAO切面中有寫到。

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface RedisCache {
    String value() default "";
    boolean required() default true;
}