Spring Security 自定义认证过滤器

继承 Filter 基类 OncePerRequestFilter 保证每个请求转发执行一次

public class MyAuthenticationProcessingFilter extends OncePerRequestFilter {

  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
      throws ServletException, IOException {

    filterChain.doFilter(requestWrapper, response);
  }

出现的问题：在 filter 中消费了 Request 中的 InputStream 导致后续的过滤器中无法调用 Request
解决方法：定义一个 HttpServletRequestWrapper 类，将输入流字节数据读取出来，以供使用，重新 getInputStream() 方法，将输入流字节数组重新封装成 ServletInputStream 输入流即可，注意字符编码

ServletRequestWrapper.java

public class ServletRequestWrapper extends HttpServletRequestWrapper {

  private byte[] body;
  private String requestParam;
  /**
   * Constructs a request object wrapping the given request.
   * @Description: 将 request 中的流信息读取出来供外部使用，将流缓存起来，传到下一个 filter 中
   * @param request The request to wrap
   * @throws IllegalArgumentException if the request is null
   */
  public ServletRequestWrapper(HttpServletRequest request) {
    super(request);
    requestParam = HttpUtil.getBodyString(request);
    body = requestParam.getBytes(Charset.forName("utf-8"));
  }

  @Override
  public BufferedReader getReader() throws IOException {
    return new BufferedReader(new InputStreamReader(getRequest().getInputStream(), Charset.forName("UTF-8")));
  }

  @Override
  public ServletInputStream getInputStream() throws IOException {
    return new CustomServletInputStream();
  }

  private class CustomServletInputStream extends ServletInputStream {

    private ByteArrayInputStream inputStream = new ByteArrayInputStream(body);

    @Override
    public boolean isFinished() {
      return false;
    }

    @Override
    public boolean isReady() {
      return false;
    }

    @Override
    public void setReadListener(ReadListener listener) {

    }

    @Override
    public int read() throws IOException {
      return inputStream.read();
    }
  }

  public String getRequestParam() {
    return requestParam;
  }
}

HttpUtil.java

public class HttpUtil {

  public static String getBodyString(ServletRequest request) {
    BufferedReader bufferedReader = null;
    InputStream inputStream = null;

    StringBuilder sb = new StringBuilder("");
    try {
      inputStream = request.getInputStream();

      bufferedReader = new BufferedReader(new InputStreamReader(inputStream, Charset.forName("utf-8")));

      String line = "";
      while ((line = bufferedReader.readLine()) != null) {
        sb.append(line);
      }
    } catch (IOException e) {
      e.printStackTrace();
    } finally {

      if (bufferedReader != null) {
        try {
          bufferedReader.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }

      if (inputStream != null) {
        try {
          inputStream.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }

    return sb.toString();
  }

}