getInputStream() has already been called for this request

Recently, I am working on a logging system , There is a module inside that records the user's operation records , Need to get the request params, Back to result, And that is requestbody The content in , Then take body I found that I couldn't get it , This article records ！

Wrong content

getInputStream() has already been called for this request

reason
ServletRequest Of getReader() and getInputStream() Two methods can only be called once , And you can't call both . So if Filter It was called once , stay Controller There can be no more calls inside

terms of settlement
First the Request Body preservation , And then through Servlet Self contained HttpServletRequestWrapper Class coverage getReader () and getInputStream () Method , Make the stream from the saved body Read . And then again Filter Lieutenant general ServletRequest Replace with MyRequestWrapper.

Add configuration class

RequestWrapper.java

package top.fate.config;

import org.apache.poi.util.IOUtils;
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

/** * @auther:Wangxl * @Emile:[email protected] * @Time:2022/6/30 16:24 */
public class RequestWrapper extends HttpServletRequestWrapper {
    

    private final byte[] body;

    public RequestWrapper(HttpServletRequest request) throws IOException {
    
        super(request);
        body = IOUtils.toByteArray(request.getInputStream());
    }

    @Override
    public BufferedReader getReader() throws IOException {
    
        return new BufferedReader(new InputStreamReader(getInputStream()));
    }

    @Override
    public ServletInputStream getInputStream() {
    
        final ByteArrayInputStream bais = new ByteArrayInputStream(body);
        return new ServletInputStream() {
    

            @Override
            public boolean isFinished() {
    
                return false;
            }

            @Override
            public boolean isReady() {
    
                return false;
            }

            @Override
            public void setReadListener(ReadListener readListener) {
    

            }

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

HttpServletRequestReplacedFilter.java

package top.fate.config;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/** * @auther:Wangxl * @Emile:[email protected] * @Time:2022/6/30 16:35 */
public class HttpServletRequestReplacedFilter implements Filter {
    

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    
        ServletRequest servletWrapper = null;
        if (servletRequest instanceof HttpServletRequest) {
    
            servletWrapper = new RequestWrapper((HttpServletRequest) servletRequest);
        }
        if (servletRequest == null) {
    
            filterChain.doFilter(servletRequest, servletResponse);
        } else {
    
            try {
    
                filterChain.doFilter(servletWrapper, servletResponse);
            } catch (IOException e) {
    
                e.printStackTrace();
            } catch (ServletException e) {
    
                e.printStackTrace();
            }
        }
    }
}