之前公司做了一個專案，需要與app對接。因為做的是通用服務，app那邊是需要直接訪問的，這樣每次請求兩邊都需要一個憑證來完成一個互相認證的過程。說一下我們專案採用的方式吧，app那邊將請求引數進行一定規則的加密，生成一個sign值，與引數一起傳遞過來，然後後端在攔截器中同樣將引數按同樣的規則加密，對比sign值是否一致，一致則通過，同理，app那邊也是這樣的認證過程。討論好方案之後自然就是開始寫程式碼了。

　　首先自然想到的是通過攔截器藍完成認證的過程。但是在測試過程中發現，攔截器都返回true了，卻到不了controller層。程式碼配置什麼的都沒問題，上網查資料才發現

request.getInputStream();  request.getReader(); request.getParameter();這些方法都只能被執行一次，再次執行就無效了。思路就是新建一個類A繼承HttpServletRequestWrapper並重寫getInputStream()方法，然後新建一個過濾器，將servletRequest替換成我們新建的類A。主要程式碼如下：

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);
        }

    }