SpringBoot @RestControllerAdvice注解对返回值统一封装

分手后的思念是犯贱 2024-04-06 13:05 120阅读 0赞

#### 目录 ####

### 一. 需求场景 ###

如下图所示，后台向前台响应数据的时候，所有的数据都需要放入自定义的封装Entity才返回给前台。现在想要每个Controller中的方法将原数据直接返回，然后通过某种方法 **统一封装** 处理。

![c47fa0313bc012f11627f1e0d34f6bb5.png][]

### 二. 前期准备 ###

⏹获取状态码的接口

public interface IStatusCode {
     
    
        int getCode();
    
        String getMsg();
    }

⏹响应状态码的枚举类

import lombok.AllArgsConstructor;
    import lombok.Getter;
    
    @Getter
    @AllArgsConstructor
    public enum ResultCodeEnum implements IStatusCode {
     
    
        SUCCESS(1000, "请求成功"),
        FAILED(1001, "请求失败"),
        VALIDATE_ERROR(1002, "参数校验失败"),
        RESPONSE_PACK_ERROR(1003, "response返回包装失败");
    
        private int code;
        private String msg;
    }

⏹业务状态码的枚举类

import lombok.AllArgsConstructor;
    import lombok.Getter;
    
    @Getter
    @AllArgsConstructor
    public enum BusinessCodeEnum implements IStatusCode {
     
    
        APP_ERROR(2000, "业务异常"),
        PRICE_ERROR(2001, "价格异常");
    
        private int code;
        private String msg;
    }

⏹自定义业务异常类

import lombok.Getter;
    
    @Getter
    public class BusinessException extends RuntimeException {
     
    
        private int code;
    
        private String msg;
    
        // 手动设置异常
        public BusinessException(IStatusCode codeEnum, String message) {
     
            // message用于用户设置抛出错误详情
            super(message);
            // 状态码
            this.code = codeEnum.getCode();
            // 状态码配套的msg
            this.msg = codeEnum.getMsg();
        }
    
        // 默认异常使用APP_ERROR状态码
        public BusinessException(String message) {
     
            super(message);
            this.code = BusinessCodeEnum.APP_ERROR.getCode();
            this.msg = BusinessCodeEnum.APP_ERROR.getMsg();
        }
    }

⏹自定义注解,标记该注解的方法不进行响应增强

让我们的方法更加 **灵活** ，可以选择增强封装或者不增强。

import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    @Target({
     ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface NotControllerResponseAdvice {
     
    }

### 三. 使用@RestControllerAdvice对响应进行增强 ###

import com.fasterxml.jackson.core.JsonProcessingException;
    import com.fasterxml.jackson.databind.ObjectMapper;
    import org.springframework.core.MethodParameter;
    import org.springframework.http.MediaType;
    import org.springframework.http.converter.HttpMessageConverter;
    import org.springframework.http.server.ServerHttpRequest;
    import org.springframework.http.server.ServerHttpResponse;
    import org.springframework.web.bind.annotation.RestControllerAdvice;
    import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
    
    import java.util.Arrays;
    import java.util.List;
    
    // 对指定包下面的Controller进行增强
    @RestControllerAdvice(basePackages = {
     "com.example.jmw.controller"})
    public class ControllerResponseAdvice implements ResponseBodyAdvice<Object> {
     
    
        @Override
        public boolean supports(MethodParameter methodParameter, Class<? extends HttpMessageConverter<?>> converterType) {
     
    
            List<Boolean> judgeResultList = Arrays.asList(
                    // :o:判断相应的类型是否为ResultVo类型
                    methodParameter.getParameterType().isAssignableFrom(ResultVo.class),
                    // :o:判断响应的方法上是否包含 NotControllerResponseAdvice 注解
                    methodParameter.hasMethodAnnotation(NotControllerResponseAdvice.class)
            );
    
            // 若包含其中一项,则不进行封装
            return !judgeResultList.contains(true);
        }
    
        @Override
        public Object beforeBodyWrite(Object body
                , MethodParameter returnType
                , MediaType selectedContentType
                , Class<? extends HttpMessageConverter<?>> selectedConverterType
                , ServerHttpRequest request
                , ServerHttpResponse response
        ) {
     
    
            // String类型不能直接包装
            if (returnType.getGenericParameterType().equals(String.class)) {
     
                ObjectMapper objectMapper = new ObjectMapper();
                try {
     
                    // 将数据包装在ResultVo里后转换为json串进行返回
                    return objectMapper.writeValueAsString(ResultVo.build(body));
                } catch (JsonProcessingException e) {
     
                	// 抛出自定义的业务异常
                    throw new BusinessException(ResultCodeEnum.RESPONSE_PACK_ERROR, e.getMessage());
                }
            }
    
            // 否则直接包装成ResultVo返回
            return ResultVo.build(body);
        }
    }

### 四. 效果 ###

### 4.1 直接返回List ###

@Controller
    @RequestMapping("/test12")
    public class Test12Controller {
     
    
        @PostMapping("/test")
        @ResponseBody
        public List<String> test() {
     
    
            return Arrays.asList("1", "2", "3");
        }
    }

⏹List被包装之后返回给前台

![30100c21f7b028ea767da4269cf80aac.png][]

### 4.2 标记NotControllerResponseAdvice注解后返回List ###

⏹ `List` 未被包装，直接返回数据给前台

![2c87032768d4af558adb8b76f15db4b9.png][]

### 4.3 直接返回字符串 ###

![c5a1312a998f039c244ed81c8901a97a.png][]

### 4.4 直接返回ResultVo类型数据 ###

⏹返回的就是ResultVo类型，无需包装，直接返回数据给前台

![821b4d7a7d4652314c2ad97f5d808480.png][]

[c47fa0313bc012f11627f1e0d34f6bb5.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/282bb76bc6c3463d97636089e2a3edfb.png
[30100c21f7b028ea767da4269cf80aac.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/1c7ae678a8c446bb92941a3beab1f3a8.png
[2c87032768d4af558adb8b76f15db4b9.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/f7b035398def4989bff41ae093768afd.png
[c5a1312a998f039c244ed81c8901a97a.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/c04b0b7132dd49aba6984bfbbc88a001.png
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