如何無消耗地多次存取HTTP Servlet請求參數？

無消耗存取HTTP Servlet請求參數

問題：

問題：

問題：

public class MultiReadHttpServletRequest extends HttpServletRequestWrapper { private ByteArrayOutputStream cachedBytes; public MultiReadHttpServletRequest(HttpServletRequest request) { super(request); } @Override public ServletInputStream getInputStream() throws IOException { if (cachedBytes == null) cacheInputStream(); return new CachedServletInputStream(cachedBytes.toByteArray()); } @Override public BufferedReader getReader() throws IOException{ return new BufferedReader(new InputStreamReader(getInputStream())); } private void cacheInputStream() throws IOException { cachedBytes = new ByteArrayOutputStream(); IOUtils.copy(super.getInputStream(), cachedBytes); } private static class CachedServletInputStream extends ServletInputStream { private final ByteArrayInputStream buffer; public CachedServletInputStream(byte[] contents) { this.buffer = new ByteArrayInputStream(contents); } @Override public int read() { return buffer.read(); } // ... Implementation for newer versions of ServletInputStream interface } }

解決方案：

public class MyFilter implements Filter {
  public void doFilter(ServletRequest request, ServletResponse response,
        FilterChain chain) throws IOException, ServletException {
    MultiReadHttpServletRequest multiReadRequest = new MultiReadHttpServletRequest((HttpServletRequest) request);
    doMyThing(multiReadRequest.getInputStream());
    chain.doFilter(multiReadRequest, response);
  }
}

要存取參數而不消耗它們，您可以擴展HttpServletRequestWrapper 並實作自訂方法快取輸入流：透過使用此類包裝原始請求，您可以存取在過濾器鏈內外多次快取輸入流，允許getParameterXXX 和doMyThing 等自訂方法讀取參數：

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