解决request.getInputStream()只能读取一次的问题

request.getInputStream()只能够读取一次，但是在实际的开发中往往需要多次读取。这样就需要我们将流写入进去，提供后续使用。方法可能有很多，

这里提供其中一种！

1：创建HttpHelper类获取流中的数据。

public class HttpHelper {    /**     * 获取请求Body     * @param request     * @return     */    private static Logger logger = LoggerFactory.getLogger(HttpHelper.class);    public static String getBodyString(ServletRequest request) {        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) {            logger.warn("getBodyString出现问题！");        } 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();    }}
2：重写HttpServletRequestWrapper类
public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {    private final byte[] body;    public BodyReaderHttpServletRequestWrapper(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) {            }        };    }}
3：在过滤器中加入如下代码
@Configurationpublic class CorsConfig extends OncePerRequestFilter {    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)            throws ServletException, IOException {        // 防止流读取一次后就没有了, 所以需要将流继续写出去，提供后续使用        ServletRequest requestWrapper = new BodyReaderHttpServletRequestWrapper(request);        String json = HttpHelper.getBodyString(requestWrapper);        filterChain.doFilter(requestWrapper, response);    }}
这里一定要注意返回的request必须是我们重写之后的，否则还是会出现问题！