解决java中Post请求，在拦截器取requestBody数据后，controller层接收的数据为空问题

原文地址：https://blog.csdn.net/weixin_43946446/article/details/121498068

解决方案如下：

1. 创建一个类BodyReaderHttpServletRequestWrapper，继承HttpServletRequestWrapper，重写getInputStream和getReader方法，把request请求体继续往下传。

`public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {

    private final byte[] body;

    public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        String sessionStream = getBodyString(request);
        body = sessionStream.getBytes(Charset.forName("UTF-8"));
    }

    public String  getBodyString(){
        return new String(body,Charset.forName("UTF-8"));
    }


    private String getBodyString(final ServletRequest request) {
        StringBuilder sb = new StringBuilder();
        InputStream inputStream = null;
        BufferedReader reader = null;
        try {
            inputStream = cloneInputStream(request.getInputStream());
            reader = new BufferedReader(new InputStreamReader(inputStream, Charset.forName("UTF-8")));
            String line = "";
            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (reader != null) {
                try {
                    reader.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return sb.toString();
    }


    public InputStream cloneInputStream(ServletInputStream inputStream) {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len;
        try {
            while ((len = inputStream.read(buffer)) > -1) {
                byteArrayOutputStream.write(buffer, 0, len);
            }
            byteArrayOutputStream.flush();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        InputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
        return byteArrayInputStream;
    }
    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(getInputStream()));
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {

        final ByteArrayInputStream bais = new ByteArrayInputStream(body);

        return new ServletInputStream() {

            @Override
            public int read() throws IOException {
                return bais.read();
            }

            public boolean isFinished() {
                return false;
            }

            public boolean isReady() {
                return false;
            }

            public void setReadListener(ReadListener readListener) {

            }
        };
    }
}` 

1. 过滤器中，检验条件通过的url，将request请求重新创建自定义的请求对象，并往下传递

`public class RequestFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

        HttpServletResponse res = (HttpServletResponse) servletResponse;
        HttpServletRequest req = (HttpServletRequest) servletRequest;
        String origin = req.getHeader("Origin");
        System.out.println("***************跨域过滤器**************");
        if(!org.springframework.util.StringUtils.isEmpty(origin)) {
            res.addHeader("Access-Control-Allow-Origin", origin);
        }
        res.addHeader("Access-Control-Allow-Methods", "*");
        res.addHeader("Access-Control-Allow-Credentials", "true");
        res.addHeader("Access-Control-Allow-Headers", "*");
        if (req.getMethod().equals("OPTIONS")) {
            res.setStatus(HttpServletResponse.SC_OK);
            return;
        }

        String uri = ((HttpServletRequest) servletRequest).getRequestURI();
        if(uri != null && containRegisterUri(uri)) {

            BodyReaderHttpServletRequestWrapper requestWrapper = new BodyReaderHttpServletRequestWrapper((HttpServletRequest) servletRequest);
            filterChain.doFilter(requestWrapper, servletResponse);
        }else{
            filterChain.doFilter(servletRequest, servletResponse);
        }

    }


    private boolean containRegisterUri(String curUri){
        String[] arr = new String[]{
                "xxx/xxxx",
                "xxx/yyyy"
        };
        List<String> urls = Arrays.asList(arr);
        for(String url : urls){
            if(curUri.contains(url)){
                return true;
            }
        }
        return false;
    }

    @Override
    public void destroy() {

    }
}` 

1. 拦截器对request对象进行转换为自定义的请求对象，获取requestBody中请求体参数。值得注意的是：拦截器中是可以注入交给spring管理的对象（如serviceImpl对象），对业务逻辑进行控制是否继续往下执行。

`@Slf4j
public class FilterPointInterceptor extends HandlerInterceptorAdapter {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        WordFilterPoint annotation = null;

        if(handler instanceof HandlerMethod) {
            annotation = ((HandlerMethod) handler).getMethodAnnotation(FilterPoint.class);
        }
        if (annotation != null) {
            log.info("***************FilterPoint**************************");

            Map parameterMap =  request.getParameterMap();
            Map reqMap = new HashMap<String,Object>();
            Set<Map.Entry<String,String[]>> entry = parameterMap.entrySet();
            Iterator<Map.Entry<String,String[]>> it = entry.iterator();
            while (it.hasNext()){
                Map.Entry<String,String[]>  me = it.next();
                reqMap.put(me.getKey(),me.getValue()[0]);
            }


            if("POST".equalsIgnoreCase(request.getMethod())) {
                BodyReaderHttpServletRequestWrapper requestWrapper = new BodyReaderHttpServletRequestWrapper(request);
                String bodyString = requestWrapper.getBodyString();
                if (JSONUtils.mayBeJSON(bodyString)) {
                    Map postMap = JSON.parseObject(bodyString, Map.class);
                    String paramString = JSON.toJSONString(reqMap);
                    log.info("****** POST paramString={}", paramString);
                    reqMap.putAll(postMap);
                }
            }
        }
        return true;
    }

}` 

1. 最后，请求在拦截器中处理过后，controller层中也可以正常接收到参数。Ps：特意在此记录一下解决的过程，有更好的建议请提出、改正！