SpringBoot(35) 自定义注解实现post请求接收单个参数值

叁歲伎倆 2023-01-06 01:23 470阅读 0赞

### 一、前言 ###

本文将基于`springboot2.4.0`实现自定义注解`RequestPostSingleParam`接收post请求单个参数值

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MjI1NTU4_size_16_color_FFFFFF_t_70]

### 二、自定义注解`RequestPostSingleParam` ###

> 处理接收单个参数的`post`请求

@Target(ElementType.PARAMETER)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface RequestPostSingleParam { 
    
        /** * Alias for {@link #name}. */
        @AliasFor("name")
        String value() default "";
    
        /** * The name of the request parameter to bind to. * * @since 4.2 */
        @AliasFor("value")
        String name() default "";
    
        /** * Whether the parameter is required. * <p> * Defaults to {@code true}, leading to an exception being thrown if the parameter is missing in the request. Switch * this to {@code false} if you prefer a {@code null} value if the parameter is not present in the request. * <p> * Alternatively, provide a {@link #defaultValue}, which implicitly sets this flag to {@code false}. */
        boolean required() default true;
    
        /** * The default value to use as a fallback when the request parameter is not provided or has an empty value. * <p> * Supplying a default value implicitly sets {@link #required} to {@code false}. */
        String defaultValue() default ValueConstants.DEFAULT_NONE;
    
    }

### 三、参数解析器 ###

@Slf4j
    public class RequestPostSingleParamMethodArgumentResolver implements HandlerMethodArgumentResolver { 
    
        private static final String POST = "post";
        private static final String APPLICATION_JSON = "application/json";
    
        /** * 判断是否需要处理该参数 * * @param parameter * the method parameter to check * @return {@code true} if this resolver supports the supplied parameter; {@code false} otherwise */
        @Override
        public boolean supportsParameter(MethodParameter parameter) { 
            // 只处理带有@RequestPostSingleParam注解的参数
            return parameter.hasParameterAnnotation(RequestPostSingleParam.class);
        }
    
        @Override
        public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
            NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception { 
            HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
            String contentType = Objects.requireNonNull(servletRequest).getContentType();
    
            if (contentType == null || !contentType.contains(APPLICATION_JSON)) { 
                log.error("《RequestPostSingleParam》 contentType需为【{}】", APPLICATION_JSON);
                throw new RuntimeException("《RequestPostSingleParam》 contentType需为application/json");
            }
    
            if (!POST.equalsIgnoreCase(servletRequest.getMethod())) { 
                log.error("《RequestPostSingleParam》 请求类型必须为post");
                throw new RuntimeException("《RequestPostSingleParam》 请求类型必须为post");
            }
            return this.bindRequestParams(parameter, servletRequest);
        }
    
        private Object bindRequestParams(MethodParameter parameter, HttpServletRequest servletRequest) { 
            RequestPostSingleParam requestPostSingleParam = parameter.getParameterAnnotation(RequestPostSingleParam.class);
            Class<?> parameterType = parameter.getParameterType();
            String requestBody = this.getRequestBody(servletRequest);
            Map paramObj = JSONObject.parseObject(requestBody, Map.class);
            if (paramObj == null) { 
                paramObj = new JSONObject();
            }
            // if (paramObj.size() > 1) { 
            // throw new RuntimeException("《RequestPostSingleParam》 post请求只支持接收单个参数!");
            // }
    
            String parameterName = StringUtils.isBlank(requestPostSingleParam.value()) ? parameter.getParameterName()
                : requestPostSingleParam.value();
            Object value = paramObj.get(parameterName);
    
            if (requestPostSingleParam.required()) { 
                if (value == null) { 
                    log.error("《RequestPostSingleParam》 require=true,参数【{}】不能为空!", parameterName);
                    throw new RuntimeException("《RequestPostSingleParam》 " + parameterName + "不能为空!");
                }
            }
    
            return ConvertUtils.convert(value, parameterType);
        }
    
        /** * 获取请求body * * @param servletRequest: * request * @return: 请求body */
        private String getRequestBody(HttpServletRequest servletRequest) { 
            StringBuilder stringBuilder = new StringBuilder();
            try { 
                BufferedReader reader = servletRequest.getReader();
                char[] buf = new char[1024];
                int length;
                while ((length = reader.read(buf)) != -1) { 
                    stringBuilder.append(buf, 0, length);
                }
            } catch (IOException e) { 
                log.error("《RequestPostSingleParam》 读取流异常", e);
                throw new RuntimeException("《RequestPostSingleParam》 读取流异常");
            }
            return stringBuilder.toString();
        }
    
    }

### 四、注册参数解析器 ###

@Configuration
    public class RequestPostSingleParamResolverConfig implements WebMvcConfigurer { 
    
        @Override
        public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) { 
            resolvers.add(new RequestPostSingleParamMethodArgumentResolver());
            WebMvcConfigurer.super.addArgumentResolvers(resolvers);
        }
    
    }

### 五、测试 ###

@Slf4j
    @RestController
    @RequestMapping("/test")
    @Api(tags = "测试api")
    public class TestController { 
    
        @PostMapping("")
        @ApiOperation("测试post请求接收单个参数")
        public Integer testPostParam(@ApiParam("id值") @RequestPostSingleParam Integer id) { 
            log.info("id: 【{}】", id);
            return id;
        }
    
    }

[http://127.0.0.1/doc.html][http_127.0.0.1_doc.html]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MjI1NTU4_size_16_color_FFFFFF_t_70 1]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MjI1NTU4_size_16_color_FFFFFF_t_70 2]

### 六、本文案例demo ###

[https://gitee.com/zhengqingya/java-workspace][https_gitee.com_zhengqingya_java-workspace]

--------------------

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[http_127.0.0.1_doc.html]: http://127.0.0.1/doc.html
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[https_gitee.com_zhengqingya_java-workspace]: https://gitee.com/zhengqingya/java-workspace