springboot HandlerIntercepter攔截器修改request body數(shù)據(jù)的操作

更新時間：2021年06月29日 09:07:05 作者：Skyler

這篇文章主要介紹了springboot HandlerIntercepter攔截器修改request body數(shù)據(jù)的操作，具有很好的參考價值，希望對大家有所幫助。

實際工作中學(xué)習(xí)技術(shù)是最快、最深刻的。當(dāng)然，自身的持續(xù)學(xué)習(xí)意識是必須的

技術(shù)棧版本：

spring boot 2.0.2

遇到事兒了

近來做業(yè)務(wù)需求，前端同學(xué)fe將userId和userName放到request header中了。

后端api接口要想使用userId和userName，每個接口都要從header中獲取。

試想一下，如果你有十個接口，那么每個接口都要寫一遍

Object.setUserId(request.getHeader("userId"))

正如下面代碼段

@RestController
@Validated
@RequestMapping("/template")
public class TemplateController {
    // 一個feign client
    @Autowired 
    TemplateClient templateClient
    @PostMapping(value = "/create", produces = MediaType.APPLICATION_JSON_VALUE)
    public ResultVO create(@RequestBody @Valid TemplateParam param, HttpServletRequest request) {
        // 每個接口都要寫一遍setXXX()方法
        param.setUserId(request.getHeader("userId"));
        param.setUserName(request.getHeader("userName"));
        return templateClient.createTemplate(param).toResultVO();
    }
}   
@Data
public class TemplateParam{
    private Long templateId; 
    private Long userId;
    private String userName;
}

解決辦法

大家都知道的兩大利器，

tomcat的Filter和spring的Intercepter(具體為HandlerIntercepter)

實現(xiàn)原理

具體方法為定義一個Filter實現(xiàn)類和一個HandlerIntercepter的實現(xiàn)類。再定義一個HttpServletRequest實現(xiàn)類，其作用分別為

Filter實現(xiàn)類：UserInfoFilter

創(chuàng)建一個入口，在這個入口中定義一個機會：將我們自定義的CustomHttpServletRequestWrapper代替HttpServletRequest隨著請求傳遞下去

HttpServletRequest實現(xiàn)類：customHttpServletRequestWrapper

因為HttpServletRequest對象的body數(shù)據(jù)只能get，不能set，即不能再次賦值。

而我們的需求是需要給HttpServletRequest賦值，所以需要定義一個HttpServletRequest實現(xiàn)類：customHttpServletRequestWrapper，這個實現(xiàn)類可以被賦值來滿足我們的需求。

HandlerIntercepter的實現(xiàn)類：CustomInterceptor

攔截請求，獲取接口方法相關(guān)信息(方法名，參數(shù)，返回值等)。從而實現(xiàn)統(tǒng)一的給request body動態(tài)賦值

實現(xiàn)思路如上所述，具體的實現(xiàn)代碼如下

代碼實現(xiàn)

聲明基礎(chǔ)bean: UserInfoParam

UserInfoParam：定義了包含userId,userName的實體bean,要想將用戶信息注入進入，需要入?yún)ο?code>XXXParam繼承UserInfoParam，攔截器中只處理@Requestbody中實現(xiàn)了UserInfoParam類的bean。

如上文controller中create方法的入?yún)ⅲ?code>TemplateParam，繼承UserInfoParam

@Data
public class TemplateParam extends UserInfoParam{
    private Long templateId; 
    // private Long userId;
    // private String userName;
}
@Data
public class UserInfoParam {
// 用戶id
private Long userId;
// 用戶名稱
private String userName;
}

定義Filter實現(xiàn)類: UserInfoFilter

@Slf4j
public class UserInfoFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        CustomHttpServletRequestWrapper customHttpServletRequestWrapper = null;
        try {
            HttpServletRequest req = (HttpServletRequest)request;
            customHttpServletRequestWrapper = new CustomHttpServletRequestWrapper(req);
        }catch (Exception e){
            log.warn("customHttpServletRequestWrapper Error:", e);
        }
        chain.doFilter((Objects.isNull(customHttpServletRequestWrapper) ? request : customHttpServletRequestWrapper), response);
    }
}

HttpServletRequest實現(xiàn)類：CustomHttpServletRequestWrapper

public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {
    // 保存request body的數(shù)據(jù)
    private String body;
    // 解析request的inputStream(即body)數(shù)據(jù)，轉(zhuǎn)成字符串
    public CustomHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
        StringBuilder stringBuilder = new StringBuilder();
        BufferedReader bufferedReader = null;
        InputStream inputStream = null;
        try {
            inputStream = request.getInputStream();
            if (inputStream != null) {
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                char[] charBuffer = new char[128];
                int bytesRead = -1;
                while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
                    stringBuilder.append(charBuffer, 0, bytesRead);
                }
            } else {
                stringBuilder.append("");
            }
        } catch (IOException ex) {
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (bufferedReader != null) {
                try {
                    bufferedReader.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        body = stringBuilder.toString();
    }
    @Override
    public ServletInputStream getInputStream() throws IOException {
        final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());
        ServletInputStream servletInputStream = new ServletInputStream() {
            @Override
            public boolean isFinished() {
                return false;
            }
            @Override
            public boolean isReady() {
                return false;
            }
            @Override
            public void setReadListener(ReadListener readListener) {
            }
            @Override
            public int read() throws IOException {
                return byteArrayInputStream.read();
            }
        };
        return servletInputStream;
    }
    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(this.getInputStream()));
    }
    public String getBody() {
        return this.body;
    }
    // 賦值給body字段
    public void setBody(String body) {
        this.body = body;
    }
}

HandlerIntercepter的實現(xiàn)類：CustomInterceptor

@Slf4j
public class CustomInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
        throws Exception {
        if (!(handler instanceof HandlerMethod)) {
            return true;
        }
        HandlerMethod handlerMethod = (HandlerMethod)handler;
        pushUserInfo2Body(request, handlerMethod);
        return true;
    }
    private void pushUserInfo2Body(HttpServletRequest request, HandlerMethod handlerMethod) {
        try{
            String userId = request.getHeader("userId");
            String userName = request.getHeader("userName");
            MethodParameter[] methodParameters = handlerMethod.getMethodParameters();
            if(ArrayUtils.isEmpty(methodParameters)) {
                return;
            }
            for (MethodParameter methodParameter : methodParameters) {
                Class clazz = methodParameter.getParameterType();
                if(ClassUtils.isAssignable(UserInfoParam.class, clazz)){
                    if(request instanceof CustomHttpServletRequestWrapper){
                        CustomHttpServletRequestWrapper requestWrapper = (CustomHttpServletRequestWrapper)request;
                        String body = requestWrapper.getBody();
                        JSONObject param = JSONObject.parseObject(body);
                        param.put("userId", userId);
                        param.put("userName", Objects.isNull(userName) ? null : URLDecoder.decode(userName, "UTF-8"));
                        requestWrapper.setBody(JSON.toJSONString(param));
                    }
                }
            }
        }catch (Exception e){
            log.warn("fill userInfo to request body Error ", e);
        }
    }

定義Configuration class，增加攔截器和過濾器的配置

WebMvcConfigurer子類：CustomWebMvcConfigurer

@Configuration
public class CustomWebMvcConfigurer implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        CustomInterceptor customInterceptor= new CustomInterceptor();
        registry.addInterceptor(customInterceptor);
    }
    @Bean
    public FilterRegistrationBean servletRegistrationBean() {
        UserInfoFilter userInfoFilter = new UserInfoFilter();
        FilterRegistrationBean<UserInfoFilter> bean = new FilterRegistrationBean<>();
        bean.setFilter(userInfoFilter);
        bean.setName("userInfoFilter");
        bean.addUrlPatterns("/*");
        bean.setOrder(Ordered.LOWEST_PRECEDENCE);
        return bean;
    }
}

到此，實現(xiàn)功能的代碼擼完了。啟動spring boot App，就可以curl訪問restful接口了

http訪問

curl -X POST \
  http://localhost:8080/template/create
  -H 'Content-Type: application/json'
  -H 'username: tiankong天空'
  -H 'userId: 11'
  -d '{
  "templateId": 1000}