使用ResponseBodyAdvice封装统一返回值

╰半夏微凉° 2023-10-14 15:48 54阅读 0赞

**目录**

ResponseBodyAdvice 接口概述

ResponseBodyAdvice 快速使用

父pom文件

pom文件

ResponseDto

MyResponseBodyAdvice

DemoController

结果展示

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

## ResponseBodyAdvice 接口概述 ##

在实际项目中，我们经常需要在请求前后进行一些操作，比如：参数解密/返回结果加密、返回值封装，打印请求参数和返回结果的日志等。这些与业务无关的东西，我们不希望写在controller方法中，造成代码重复可读性变差。这里，我们经常使用@ControllerAdvice和RequestBodyAdvice、ResponseBodyAdvice来对请求前后进行处理（本质上就是AOP），来实现日志记录每一个请求的参数和返回结果。  
  
1、ResponseBodyAdvice 接口允许在执行 @ResponseBody 或 ResponseEntity 控制器方法之后，但在使用 HttpMessageConverter 写入响应体之前自定义响应，进行功能增强。通常用于 加密，签名，统一数据格式等。

2、ResponseBodyAdvice 接口一共有两个方法：

//
    // Source code recreated from a .class file by IntelliJ IDEA
    // (powered by FernFlower decompiler)
    //
    
    package org.springframework.web.servlet.mvc.method.annotation;
    
    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.lang.Nullable;
    
    public interface ResponseBodyAdvice<T> {
        boolean supports(MethodParameter var1, Class<? extends HttpMessageConverter<?>> var2);
    
        @Nullable
        T beforeBodyWrite(@Nullable T var1, MethodParameter var2, MediaType var3, Class<? extends HttpMessageConverter<?>> var4, ServerHttpRequest var5, ServerHttpResponse var6);
    }

## ResponseBodyAdvice 快速使用 ##

1、使用方式：自定义类实现 ResponseBodyAdvice 接口，然后在类上标记 @ControllerAdvice 或@RestControllerAdvice 注解即可自动识别并进行功能增强。

2、下面以对返回数据封装统一格式为例进行演示（**注意仅对返回值为 ResponseEntity 或者是有@ResponseBody 注解的控制器方法进行拦截，@RestController 相当于是类中的所有方法上都加了 @ResponseBody**）。

3、注意如果控制层目标方法往外抛出了异常，则不再进入 ResponseBodyAdvice（需要使用@ExceptionHandler(value = Exception.class)）

![51fd1bacfdc145389f056c0907163b5f.png][]

### 父pom文件 ###

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
    
            <version>2.2.5.RELEASE</version>
            <relativePath/> 
        </parent>
        <groupId>com.chensir</groupId>
        <artifactId>springboot</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>springboot</name>
        <description>springboot</description>
        <properties>
            <java.version>8</java.version>
        </properties>
    
        <packaging>pom</packaging>
    
        <modules>
            <module>servlet</module>
            <module>spring-interceptor</module>
            <module>spring-aop</module>
            <module>spring-united-reslut</module>
        </modules>
    
        <dependencies>
    
            <dependency>
                <groupId>com.aliyun</groupId>
                <artifactId>alibaba-dingtalk-service-sdk</artifactId>
                <version>2.0.0</version>
            </dependency>
    
            <dependency>
                <groupId>cn.hutool</groupId>
                <artifactId>hutool-all</artifactId>
                <version>5.8.3</version>
            </dependency>
    
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.18.24</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    </project>

### pom文件 ###

### ResponseDto<T> ###

// 泛型
    @Data
    public class ResponseDto<T> implements Serializable {
    
        // 返回码(内部拟定)
        private int code;
    
        // 返回信息
        private String message;
    
        private T data;
    }

### MyResponseBodyAdvice ###

package com.chensir.advice;
    
    import cn.hutool.core.util.StrUtil;
    import cn.hutool.json.JSONUtil;
    import com.chensir.model.ResponseDto;
    import org.springframework.core.MethodParameter;
    import org.springframework.http.MediaType;
    import org.springframework.http.converter.StringHttpMessageConverter;
    import org.springframework.http.server.ServerHttpRequest;
    import org.springframework.http.server.ServerHttpResponse;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.bind.annotation.RestControllerAdvice;
    import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
    
    import javax.servlet.http.HttpServletRequest;
    
    // 拦截范围为 com.chensir.controller包下内容
    @RestControllerAdvice(basePackages = {"com.chensir.controller"})
    public class MyResponseBodyAdvice implements ResponseBodyAdvice {
        // 是否开启拦截 true开启 false不开启
        @Override
        public boolean supports(MethodParameter methodParameter, Class aClass) {
            // 此处应该改为true,否则除了异常外 走到此处为false后就直接返回,也不再继续往下走了！
            return true;
        }
    
        // 如果接口返回异常就在此处拦截 进行封装;value = Exception.class 对所有的异常均拦截！
        @ExceptionHandler(value = Exception.class)
        public Object defaultErrorHandler(HttpServletRequest req, Exception ex){
            ResponseDto<Object> responseDto = new ResponseDto<>();
            responseDto.setCode(501);
            responseDto.setMessage(ex.getMessage());
            return responseDto;
        }
    
        @Override
        public Object beforeBodyWrite(Object body, MethodParameter methodParameter, MediaType mediaType, Class aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {
            // 有的接口再返回时会自己封装code,message,data。如果body是ResponseDto类型的实例，那么就直接返回body
            if(body instanceof ResponseDto){
                return body;
            }
    
            ResponseDto<Object> responseDto = new ResponseDto<>();
            // 先用hutool定义为null
            String message = StrUtil.EMPTY;
            responseDto.setCode(0);
            responseDto.setMessage(message);
            responseDto.setData(body);
    
            // 如果是string类型就用json封装一下;
            if (aClass == StringHttpMessageConverter.class) {
                return JSONUtil.toJsonStr(responseDto);
            } else {
                return responseDto;
            }
    
        }
    }

### DemoController ###

@RestController
    @RequestMapping("/api")
    public class DemoController {
    
        @GetMapping("/demo1")
        public String demo1() {
            return "demo1";
        }
    
        @GetMapping("/demo2")
        public List<Integer> demo2(){
            ArrayList<Integer> arrayList = CollectionUtil.newArrayList(1, 2, 3, 4, 5, 6);
            return arrayList;
        }
    
        @GetMapping("/demo3")
        public Integer demo3(){
            int a = 5/0;
            return a;
        }
    }

### 结果展示 ###

![e9b258fd38f84781b6a5b451853d836e.png][]

![b42e7b7178004af79bc9db1e8133fb16.png][]

![20b1201eca3e43d48454cdc0ab9c116a.png][]

[51fd1bacfdc145389f056c0907163b5f.png]: https://img-blog.csdnimg.cn/51fd1bacfdc145389f056c0907163b5f.png
[e9b258fd38f84781b6a5b451853d836e.png]: https://img-blog.csdnimg.cn/e9b258fd38f84781b6a5b451853d836e.png
[b42e7b7178004af79bc9db1e8133fb16.png]: https://img-blog.csdnimg.cn/b42e7b7178004af79bc9db1e8133fb16.png
[20b1201eca3e43d48454cdc0ab9c116a.png]: https://img-blog.csdnimg.cn/20b1201eca3e43d48454cdc0ab9c116a.png