SpringBoot过滤器如何获取POST请求的JSON参数

parameterMap = httpRequest.getParameterMap();
String requestMethod = httpRequest.getMethod();
String remoteAddr = httpRequest.getRemoteAddr();
int remotePort = httpRequest.getRemotePort();

ServletInputStream inputStream = httpRequest.getInputStream();
InputStreamReader reader = new InputStreamReader(inputStream,StandardCharsets.UTF_8);
BufferedReader bfReader = new BufferedReader(reader);
StringBuilder sb = new StringBuilder();
String line;
while ((line = bfReader.readLine()) != null){
sb.append(line);
}
System.out.println(sb.toString());

public class RequestWrapper extends HttpServletRequestWrapper {
    private final byte[] body;
    public RequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        //保存一份InputStream，将其转换为字节数组
        body = StreamUtils.copyToByteArray(request.getInputStream());
    }
	//转换成String
    public String getBodyString(){
        return new String(body,StandardCharsets.UTF_8);
    }
    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(getInputStream()));
    }
	//把保存好的InputStream，传下去
    @Override
    public ServletInputStream getInputStream() throws IOException {
        final ByteArrayInputStream bais = new ByteArrayInputStream(body);
        return new ServletInputStream() {
            @Override
            public int read() throws IOException {
                return bais.read();
            }
            @Override
            public boolean isFinished() {
                return false;
            }
            @Override
            public boolean isReady() {
                return false;
            }
            @Override
            public void setReadListener(ReadListener readListener) {
            }
        };
    }
}