异常：getReader() has already been called for this request

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一个流不能读两次异常，这种异常一般出现在框架或者拦截器中读取了request中的流的数据，我们在业务代码中再次读取（如@requestBody），由于流中的数据已经没了，所以第二次读取的时候就会抛出异常。

解决方案：定义一个过滤器将流中的数据读取到一个数组中，并重写getInputStream()和getRead()方法，后续获取流中的数据的时候，直接去数组中读取，代码实现如下：

class DealStreamFilter extends AbstractWebFilter {

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        logger.info("进入DealStreamFilter。。。。。。");
        ServletRequest requestWrapper = null;
        if (servletRequest instanceof HttpServletRequest) {
            requestWrapper = new BodyReaderHttpServletRequestWrapper((HttpServletRequest) servletRequest);
        }
        if (null == requestWrapper) {
            filterChain.doFilter(servletRequest, servletResponse);
        } else {
            filterChain.doFilter(requestWrapper, servletResponse);
        }
    }

    static class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {

        private final byte[] body;

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

        private byte[] toByteArray(InputStream in) throws IOException {

            ByteArrayOutputStream out = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024 * 4];
            int n = 0;
            while ((n = in.read(buffer)) != -1) {
                out.write(buffer, 0, n);
            }
            return out.toByteArray();
        }

        @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();
                }
            };
        }
    }
}

将过滤器配置到配置文件：

<bean id="dealStreamFilter" class="com.pingan.apollo.filter.DealStreamFilter">
    <property name="patterns" >
        <list>
            <value>/loan/device/report.do</value>
        </list>
    </property>
    <property name="order" >
        <value>-999999</value>
    </property>
</bean>