SpringBoot项目中使用request.getInputStream()获取参数时出现java.io.IOException: Stream closed

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原因：@RequestBody注解会先调用request.getInputStream()这个方法获取参数，然而request.getInputStream()这个流只能被读取一次，所以我们再次读取这个流就会报错。
解决方案： 最简单的方案就是 先读取流，然后在将流写进去就行了

新建HttpHelper （用于读取Body）
package com.xxx.util.core.filter.request;

import javax.servlet.http.HttpServletRequest;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;

public class HttpHelper {

public static String getBodyString(HttpServletRequest request) throws IOException {
    StringBuilder sb = new StringBuilder();
    InputStream inputStream = null;
    BufferedReader reader = null;
    try {
        inputStream = 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();
}

}

新建RequestReaderHttpServletRequestWrapper（防止流丢失）
package com.xxx.util.core.filter.request;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.Charset;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class RequestReaderHttpServletRequestWrapper extends HttpServletRequestWrapper{

private final byte[] body;

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

@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();
        }

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

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

        @Override
        public void setReadListener(ReadListener readListener) {

        }
    };
}

}

新建HttpServletRequestReplacedFilter(过滤器)
package com.xxx.util.core.filter.request;

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

public class HttpServletRequestReplacedFilter implements Filter {

@Override
public void destroy() {

}

@Override
public void doFilter(ServletRequest request, ServletResponse response,
                     FilterChain chain) throws IOException, ServletException {
    ServletRequest requestWrapper = null;
    if(request instanceof HttpServletRequest) {
        requestWrapper = new RequestReaderHttpServletRequestWrapper((HttpServletRequest) request);
    }
    //获取请求中的流如何，将取出来的字符串，再次转换成流，然后把它放入到新request对象中。
    // 在chain.doFiler方法中传递新的request对象
    if(requestWrapper == null) {
        chain.doFilter(request, response);
    } else {
        chain.doFilter(requestWrapper, response);
    }
}

@Override
public void init(FilterConfig arg0) throws ServletException {

}

}

最后我们只需要在Application.java中加上如下代码注入过滤器即可
@Bean

public FilterRegistrationBean httpServletRequestReplacedRegistration() {
    FilterRegistrationBean registration = new FilterRegistrationBean();
    registration.setFilter(new HttpServletRequestReplacedFilter());
    registration.addUrlPatterns("/*");
    registration.addInitParameter("paramName", "paramValue");
    registration.setName("httpServletRequestReplacedFilter");
    registration.setOrder(1);
    return registration;
}

如下代码即可在拦截其中获取body且保证了controller中依旧可以再次获取
HttpHelper.getBodyString(request);

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