getReader() has already been called for this request

Problem site ：

reason :

HttpServletRequest Of getInputStream() and getReader() Can only be read once .

because We use @RequestBody annotation , Read body Parameters ; and also Wrote interceptors , We also need to post request ,body Take out the data .
because @RequestBody It is also read in the form of stream , After a stream reading, it's gone .

Solution ：

Filters take precedence over interceptors , Let's write a filter , Inside the filter Stream data copy One for use , That is to say, copy .
Just use our replicated stream data on the interceptor .

BodyWrapperFilter.java

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


/**
 * @Author: JCccc
 * @Date: 2022-6-12 10:35
 * @Description:
 */
public class BodyWrapperFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        ServletRequest requestWrapper = null;
        if(servletRequest instanceof HttpServletRequest) {
            requestWrapper = new CustomHttpServletRequestWrapper((HttpServletRequest) servletRequest);
        }
        if(requestWrapper == null) {
            filterChain.doFilter(servletRequest, servletResponse);
        } else {
            filterChain.doFilter(requestWrapper, servletResponse);
        }
    }
}

CustomHttpServletRequestWrapper.java

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
import java.nio.charset.StandardCharsets;

/**
 * @Author: JCccc
 * @Date: 2022-6-12 10:36
 * @Description:   Rewrite your own  RequestWrapper  take out body Use it for yourself 
 */

public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {
    private byte[] body;
    public CustomHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        BufferedReader reader = request.getReader();
        try (StringWriter writer = new StringWriter()) {
            int read;
            char[] buf = new char[1024 * 8];
            while ((read = reader.read(buf)) != -1) {
                writer.write(buf, 0, read);
            }
            this.body = writer.getBuffer().toString().getBytes();
        }
    }
    public String getBody(){
        return new String(body, StandardCharsets.UTF_8);
    }
    @Override
    public ServletInputStream getInputStream() {
        final ByteArrayInputStream byteArrayInputStream = 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 byteArrayInputStream.read();
            }
        };
    }
    @Override
    public BufferedReader getReader() {
        return new BufferedReader(new InputStreamReader(this.getInputStream()));
    }
}

WebApplicationConfig.java

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @Author: JCccc
 * @Date: 2022-6-23 10:52
 * @Description:
 */
@Configuration
public class WebApplicationConfig {

    @Bean
    BodyWrapperFilter getBodyWrapperFilter(){
        return new BodyWrapperFilter();
    }
    @Bean("bodyWrapperFilter")
    public FilterRegistrationBean<BodyWrapperFilter> checkUserFilter(BodyWrapperFilter bodyWrapperFilter) {
        FilterRegistrationBean<BodyWrapperFilter> registrationBean = new FilterRegistrationBean();
        registrationBean.setFilter(bodyWrapperFilter);
        registrationBean.addUrlPatterns("/*");
        registrationBean.setOrder(1);
        registrationBean.setAsyncSupported(true);
        return registrationBean;
    }

}

And then in the interceptor , Take out if we want to body, We use it this way instead ：
 

CustomHttpServletRequestWrapper wrapper = (CustomHttpServletRequestWrapper) request;
String  nowParams = wrapper.getBody();

effect ：

 

well , That's it .