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前言

公司内部系统老是有人填表单复制粘贴老是整出前后空格来.

前端项目烂尾, 考虑在服务端增加统一的trim处理.

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一、实现

1.1 @Trim

• 基于hutools的StrUtil.trim(value,mode)方法
• 注解在controller方法参数上时作为开关

/*** Based on {@code cn.hutool.core.util.StrUtil.trim(value, mode)}* <p>* Usage:* <p>* In order to activate the processing, add the annotation on parameters* that were also annotated with {@code @RequestBody}. This will trigger* recursive checking of the fields in the parameters.* <p>* To trim specific fields, annotate on that field.* <p>* If the field is not a String type, the fields to be trimmed in the* object field also have to be annotated with {@code @Trim}.** <pre>* public MODIFIER method({@code @RequestBody @Trim }ParamClass){}** class ParamClass {*      {@code @Trim}*      private String trimmingField;**      {@code @Trim}*      private NoneStringField nonStringField;* }** class NoneStringField {*      {@code @Trim}*      private String nonStringTrimmingField;* }* </pre>** @author hp* @see com.luban.common.base.http.servlet.TrimRequestResponseBodyMethodProcessorDecorator*/
@Documented
@Inherited
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.PARAMETER, ElementType.FIELD})
public @interface Trim {Mode value() default Mode.ALL;@Getter@AllArgsConstructorenum Mode implements BaseEnum<Mode, Integer> {/***/END(1, "trimEnd"), ALL(0, "trimAll"), START(-1, "trimStart"),;private final Integer code;private final String name;}
}

1.2 TrimRequestResponseBodyMethodProcessorDecorator

• 装饰者模式实现, 保留功能同时增强自定义trim处理
• trim目前固定基于hutools, 扩展自定义可以调整为提供一个facade设计注入这个类来提供具体的trim功能

 
/*** Replace RequestResponseBodyMethodProcessor or add this decorator before it.* <p>* Consider this example of configuring the Decorator** <pre>** {@code @RequiredArgsConstructor}* {@code @Configuration}* public class HandlerMethodArgumentResolverAutoConfiguration {**     private final RequestMappingHandlerAdapter requestMappingHandlerAdapter;*     private final List<HttpMessageConverter<?>> converters;**     {@code @PostConstruct}*     public void setRequestExcelArgumentResolver() {*         List<HandlerMethodArgumentResolver> argumentResolvers = this.requestMappingHandlerAdapter.getArgumentResolvers();*         List<HandlerMethodArgumentResolver> resolverList = new ArrayList<>();*         resolverList.add(new TrimRequestResponseBodyMethodProcessorDecorator(new RequestResponseBodyMethodProcessor(converters)));*         assert argumentResolvers != null;*         resolverList.addAll(argumentResolvers);*         this.requestMappingHandlerAdapter.setArgumentResolvers(resolverList);*     }* }** </pre>** @author hp* @see RequestMappingHandlerAdapter*/
public class TrimRequestResponseBodyMethodProcessorDecorator implements HandlerMethodArgumentResolver {private final RequestResponseBodyMethodProcessor processor;public TrimRequestResponseBodyMethodProcessorDecorator(@NonNull RequestResponseBodyMethodProcessor processor) {this.processor = processor;}@Overridepublic boolean supportsParameter(@NonNull MethodParameter parameter) {return processor.supportsParameter(parameter);}@Overridepublic Object resolveArgument(@NonNull MethodParameter parameter, ModelAndViewContainer mavContainer, @NonNull NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {final Object o = processor.resolveArgument(parameter, mavContainer, webRequest, binderFactory);if (Objects.isNull(o)) {return parameter.isOptional() ? Optional.empty() : null;}// 开关parameter = parameter.nestedIfOptional();if (!parameter.hasParameterAnnotation(Trim.class)) {return o;}// 拿到真实数据对象, 因为原生支持Optional封装Object object;if (parameter.isOptional()) {final Optional<?> optional = (Optional<?>) o;assert optional.isPresent();object = optional.get();} else {object = o;}// 范型情况, 找到真实的对象Class<?> targetClass;if (parameter.getNestedGenericParameterType() instanceof Class<?> clazz) {targetClass = clazz;} else {ResolvableType resolvableType = ResolvableType.forMethodParameter(parameter);targetClass = resolvableType.resolve();}if (Objects.isNull(targetClass)) {return o;}trimObject(targetClass, object);return o;}private static void trimObject(Class<?> targetClass, Object object) {if (Objects.isNull(targetClass) || targetClass == Object.class) {return;}ReflectionUtils.doWithFields(targetClass,field -> {final Trim fieldTrim = field.getAnnotation(Trim.class);assert fieldTrim != null;if (field.getType() == String.class) {ReflectionUtils.makeAccessible(field);final String stringVal = (String) field.get(object);final String trimmedVal = StrUtil.trim(stringVal, fieldTrim.value().getCode());field.set(object, trimmedVal);} else {ReflectionUtils.makeAccessible(field);final Object value = field.get(object);// 从实际对象取, 避免范型问题final Class<?> fieldClass = value.getClass();trimObject(fieldClass, value);}},field -> (AnnotatedElementUtils.hasAnnotation(field, Trim.class)));}
}

1.3 Configuration

• 1.1 仅实现请求参数处理, 响应未实现, 所以配置上仅配置参数处理器即可, 添加到原生处理器之前即可

@RequiredArgsConstructor
@Configuration
public class HandlerMethodArgumentResolverAutoConfiguration {private final RequestMappingHandlerAdapter requestMappingHandlerAdapter;private final List<HttpMessageConverter<?>> converters;@PostConstructpublic void setRequestExcelArgumentResolver() {List<HandlerMethodArgumentResolver> argumentResolvers = this.requestMappingHandlerAdapter.getArgumentResolvers();List<HandlerMethodArgumentResolver> resolverList = new ArrayList<>();resolverList.add(new TrimRequestResponseBodyMethodProcessorDecorator(new RequestResponseBodyMethodProcessor(converters)));assert argumentResolvers != null;resolverList.addAll(argumentResolvers);this.requestMappingHandlerAdapter.setArgumentResolvers(resolverList);}
}

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二、测试

2.1 测试用例

• RequestResponseBodyMethodProcessor 翻了下源码, 支持Optional封装, 所以用例也测试一下这种场景

@Data
public static class JsonPayload {@Trim(Trim.Mode.START)private String data;
}@Data
public static class JsonPayload2 {@Trimprivate JsonPayload data;
}@PostMapping("/json")
public Returns<String> json(@RequestBody @Trim JsonPayload jsonPayload) {return Returns.success(jsonPayload.data);
}@PostMapping("/json2")
public Returns<String> json2(@RequestBody @Trim Optional<JsonPayload> jsonPayload) {if (jsonPayload.isEmpty()) {return Returns.fail();}return Returns.success(jsonPayload.get().data);
}@PostMapping("/json3")
public Returns<String> json3(@RequestBody @Trim JsonPayload2 jsonPayload) {return Returns.success(jsonPayload.data.data);
}@PostMapping("/json4")
public Returns<String> json4(@RequestBody @Trim Optional<JsonPayload2> jsonPayload) {if (jsonPayload.isEmpty()) {return Returns.fail();}return Returns.success(jsonPayload.get().data.data);
}

2.2 测试结果

2.2.1 Test no.1

# request
POST http://localhost:9999/json
Content-Type: application/json{"data": " 123 "
}

# response
{"code": 200,"message": "操作成功","data": "123 "
}

2.2.2 Test no.2

• Optional包装

# request
POST http://localhost:9999/json2
Content-Type: application/json{"data": " 123 "
}

# response
{"code": 200,"message": "操作成功","data": "123 "
}

2.2.3 Test no.3

• 嵌套对象
• 外层对象注解属性trim两头, 但是内部string属性覆盖为trim开头

# request
POST http://localhost:9999/json3
Content-Type: application/json{"data": {"data": " 123 "}
}

# response
{"code": 200,"message": "操作成功","data": "123 "
}

2.2.4 Test no.4

• Optional包装 + 嵌套对象

# request
POST http://localhost:9999/json4
Content-Type: application/json{"data": {"data": " 321 "}
}

# response
{"code": 200,"message": "操作成功","data": "321 "
}