request.getInputStream以流的方式读取请求只能读取一次

当项目上用了 request.getInputStream以流的方式读取请求，而实际项目中通常会用到一些拦截器，作一些校验，发现只能读取一次，真正到Controller里，发现是不能用的。

好比，前端请求时以json方式提交 ，后台用用@RequestBody或者用流 作json到对象的解析，这时这个json串里有个参数要放在拦截器里校验一下

在拦截器里以流的形式读取了，后台这就取不到参数

解决办法，网上好多人是加了个过滤器，把请求包装一下，

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

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

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        ServletRequest requestWrapper = null;
        if (request instanceof HttpServletRequest) {
            requestWrapper = new SdHttpServletWrapper((HttpServletRequest) request);
        }
        if (null == requestWrapper) {
            chain.doFilter(request, response);
        } else {
            chain.doFilter(requestWrapper, response);
        }
    }

    @Override
    public void destroy() {

    }

}

import org.apache.commons.lang.StringUtils;

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;
import java.nio.charset.Charset;

public class SdHttpServletWrapper extends HttpServletRequestWrapper {
    private final byte[] body;

    public SdHttpServletWrapper(HttpServletRequest request)
            throws IOException {
        super(request);
        body = readBytes(request.getReader(), "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();
            }
        };
    }

    /**
     * 经过BufferedReader和字符编码集转换成byte数组
     *
     * @param br
     * @param encoding
     * @return
     * @throws IOException
     */
    private byte[] readBytes(BufferedReader br, String encoding) throws IOException {
        String str = null, retStr = "";
        while ((str = br.readLine()) != null) {
            retStr += str;
        }
        if (StringUtils.isNotBlank(retStr)) {
            return retStr.getBytes(Charset.forName(encoding));
        }
        return null;
    }


}

<filter>
		<filter-name>springFilter</filter-name>
		<filter-class> com.XXXXX.RequestFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>springFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>

还有一种办法就是前端请求时，把要校验的参数，拼到url后面，这样后台这能够同时用@RequestBody 和request.getparametere获取参数

POST /srs/manage/sysparam/query?token=dsfdsfsdfsdfs HTTP/1.1
Host: srs.xxx.com
Content-Type: application/json
Cache-Control: no-cache
Postman-Token: a52c36d2-d42d-4fc5-3132-8ad03dd65a08

 {"classCode":"srs.txn.type",
    "code":"P",
    "name":""
}