HttpServletRequest取请求体数据的问题

　　以前公司作了一个项目，须要与app对接。由于作的是通用服务，app那边是须要直接访问的，这样每次请求两边都须要一个凭证来完成一个互相认证的过程。说一下咱们项目采用的方式吧，app那边将请求参数进行必定规则的加密，生成一个sign值，与参数一块儿传递过来，而后后端在拦截器中一样将参数按一样的规则加密，对比sign值是否一致，一致则经过，同理，app那边也是这样的认证过程。讨论好方案以后天然就是开始写代码了。

　　首先天然想到的是经过拦截器蓝完成认证的过程。可是在测试过程当中发现，拦截器都返回true了，却到不了controller层。代码配置什么的都没问题，上网查资料才发现

request.getInputStream();  request.getReader(); request.getParameter();这些方法都只能被执行一次，再次执行就无效了。思路就是新建一个类A继承HttpServletRequestWrapper并重写getInputStream()方法，而后新建一个过滤器，将servletRequest替换成咱们新建的类A。主要代码以下：

public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {

    private final String body;

    public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        StringBuilder stringBuilder = new StringBuilder();
        BufferedReader bufferedReader = null;
        try {
            InputStream inputStream = request.getInputStream();
            if (inputStream != null) {
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                char[] charBuffer = new char[128];
                int bytesRead = -1;
                while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
                    stringBuilder.append(charBuffer, 0, bytesRead);
                }
            } else {
                stringBuilder.append("");
            }
        } catch (IOException ex) {
            throw ex;
        } finally {
            if (bufferedReader != null) {
                try {
                    bufferedReader.close();
                } catch (IOException ex) {
                    throw ex;
                }
            }
        }
        body = stringBuilder.toString();
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());
        ServletInputStream servletInputStream = new ServletInputStream() {
            public int read() throws IOException {
                return byteArrayInputStream.read();
            }
        };
        return servletInputStream;
    }

    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(this.getInputStream()));
    }

    public String getBody() {
        return this.body;
    }
}

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {

        ServletRequest requestWrapper = null;
        if (request instanceof HttpServletRequest) {
            requestWrapper = new BodyReaderHttpServletRequestWrapper((HttpServletRequest) request);
        }
        if (null == requestWrapper) {
            chain.doFilter(request, response);
        } else {
            chain.doFilter(requestWrapper, response);
        }

    }