servlet request参数只能取一次解决方法

解决方法,建一个包装类

package com.g4m.admin.conf;

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

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

import org.apache.commons.io.IOUtils;

/**
 * Wrap the generic httpServletRequest
 */
public class HttpRequestWrapper extends HttpServletRequestWrapper {

    private String body;

    private ServletInputStream inputStream;

    private BufferedReader reader;

    private String requestURI;

    private StringBuilder requestURL;

    private String servletPath;

    private Map<String, ?> params;

    public HttpRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        if (!isMultipart()) {
            preLoadBody(request);
        }
    }

    private void preLoadBody(HttpServletRequest request) throws IOException {
        Charset charset = Charset.forName(getCharacterEncoding());
        byte[] bodyBytes = IOUtils.toByteArray(request.getInputStream());
        body = new String(bodyBytes, charset);
        inputStream = new RequestCachingInputStream(body.getBytes(getCharacterEncoding()));
    }

    public final boolean isMultipart() {
        String contentType = getContentType();
        return contentType != null && contentType.toLowerCase().startsWith("multipart/");
    }

    @Override
    public final String getContentType() {
        String _contentType = getParameter("_contentType");
        if (_contentType != null) {
            return _contentType;
        }
        return super.getContentType();
    }

    public String getBody() {
        if (isMultipart()) {
            throw new IllegalStateException("multipart request does not support preloaded body");
        }
        return body;
    }

    @Override
    public String getMethod() {
        String _method = getParameter("_method");
        if (_method != null) {
            return _method;
        }
        return super.getMethod();
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        if (inputStream != null) {
            return inputStream;
        }
        return super.getInputStream();
    }

    @Override
    public BufferedReader getReader() throws IOException {
        if (reader == null) {
            reader = new BufferedReader(new InputStreamReader(inputStream, getCharacterEncoding()));
        }
        return reader;
    }

    @Override
    public final String getCharacterEncoding() {
        String defaultEncoding = super.getCharacterEncoding();
        return defaultEncoding != null ? defaultEncoding : "UTF-8";
    }

    public void setParams(Map<String, ?> params) {
        this.params = params;
    }

    /**
     * used to cache the request inputstream
     *
     * @author sylorl
     * @date Mar 10, 2015
     */
    private static class RequestCachingInputStream extends ServletInputStream {
        private final ByteArrayInputStream inputStream;
        public RequestCachingInputStream(byte[] bytes) {
            inputStream = new ByteArrayInputStream(bytes);
        }
        @Override
        public int read() throws IOException {
            return inputStream.read();
        }
        @Override
        public boolean isFinished() {
            return false;
        }
        @Override
        public boolean isReady() {
            return false;
        }
        @Override
        public void setReadListener(ReadListener readListener) {

        }
    }

    @Override
    public String getRequestURI() {
        if (this.requestURI == null) {
            return super.getRequestURI();
        }
        return super.getRequestURI();
    }

    @Override
    public StringBuffer getRequestURL() {
        if (this.requestURL == null) {
            return super.getRequestURL();
        }
        return new StringBuffer(this.requestURL.toString());
    }

    @Override
    public String getServletPath() {
        if (servletPath == null) {
            return super.getServletPath();
        }
        return this.servletPath;
    }

    public void setRequestURI(String requestURI, HttpServletRequest request) {
        this.servletPath = requestURI;
        this.requestURI = request.getContextPath() + requestURI;
        this.requestURL = new StringBuilder().append(request.getProtocol())
                .append("://")
                .append(request.getLocalAddr())
                .append("/")
                .append(servletPath);
    }
    
    @Override
    public String[] getParameterValues(String name) {
        if (params != null) {
            Object v = params.get(name);
            if (v == null) {
                return null;
            } else if (v instanceof String[]) {
                return (String[]) v;
            } else if (v instanceof String) {
                return new String[]{(String) v};
            } else {
                return new String[]{v.toString()};
            }
        }
        return super.getParameterValues(name);
    }

    @Override
    public String getParameter(String name) {
        if (params != null) {
            Object v = params.get(name);
            if (v == null) {
                return null;
            } else if (v instanceof String[]) {
                String[] strArr = (String[]) v;
                if (strArr.length > 0) {
                    return strArr[0];
                } else {
                    return null;
                }
            } else if (v instanceof String) {
                return (String) v;
            } else {
                return v.toString();
            }
        }
        return super.getParameter(name);
    }

    @Override
    public Map<String, String[]> getParameterMap() {
        if (params != null) {
            Map<String, String[]> map = new HashMap<String, String[]>();
            for (Object key : params.keySet()) {
                Object v = params.get((String) key);
                String[] strArr = null;
                if (v == null) {
                    return null;
                } else if (v instanceof String[]) {
                    strArr = (String[]) v;
                } else if (v instanceof String) {
                    strArr = new String[1];
                    strArr[0] = (String) v;
                } else {
                    strArr = new String[1];
                    strArr[0] = v.toString();
                }
                map.put((String) key, strArr);
            }
            return map;
        }
        return super.getParameterMap();
    }
}

在过滤器中将request转成包装类

import org.springframework.stereotype.Component;

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

/**
 * @author haosenwei[haosenwei@dubmic.com]
 * @date 2019-05-16 22:17
 * <p>Copyright 2008-2019 snsndk.com</p>
 */
@Component
public class LogCostFilter implements Filter {

    @Override
    public void init(javax.servlet.FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        long start = System.currentTimeMillis();
        filterChain.doFilter(new HttpRequestWrapper((HttpServletRequest) servletRequest),servletResponse);
        System.out.println("Execute cost="+(System.currentTimeMillis()-start));
    }

    @Override
    public void destroy() {

    }
}

在代码中就可以多次获取了

ServletInputStream inputStream = req.getInputStream();
String s = convertStreamToString(inputStream);
System.out.println(s);
Map<String, String[]> parameterMap = req.getParameterMap();
parameterMap.forEach((s1, strings) -> {
    System.out.println(s1 + "=" + Arrays.toString(strings));
});