寻找HttpServletResponseWrapper的捕获impl

问题描述

JavaEE API附带了HttpServletResponseWrapper，引用javadoc，提供了一个方便的HttpServletResponse接口实现，可以由希望调整Servlet响应的开发人员进行子类化。没有子类化，这个类只是将所有调用传递给包装的响应对象。请求有一个类似的包装器。

The JavaEE API comes with the HttpServletResponseWrapper which, to quote the javadoc, "provides a convenient implementation of the HttpServletResponse interface that can be subclassed by developers wishing to adapt the response from a Servlet." Without subclassing, this class just passes all calls through to the wrapped response object. There's a similar wrapper for requests.

任何人都可以指向任何提供这些类的有用子类实现的实用程序库吗？特别是，我正在寻找响应包装器的子类，它捕获写入的响应（作为String，byte []，无论什么是合适的）并通过API方法公开它。

Can anyone point me at any utility libraries that provide useful subclass implementations of these classes? Particularly, I'm looking for a subclass of the response wrapper that captures the written response (as a String, byte[], whatever's appropriate) and exposes it via an API method.

我自己写了一个相当半生不熟的版本，但坦率地说，我不应该这样做，我宁愿扔掉它并使用一个现成的。

I've written a rather half-baked version myself, but frankly, I shouldn't have to, and I'd rather throw it away and use one off the shelf.

推荐答案

我不知道任何实现，即使只需写入ByteArrayOutputStream就可以轻松调整gzip示例。您还可以通过查看其他响应包装器实现来获取想法：

I am not aware of any implementation, even though the gzip example can be adapted easily by just writing to a ByteArrayOutputStream. You can also take ideas by looking at other response wrapper implementations at:

• 。您可以找到包装请求和响应的示例：

  There is the classic article in JavaWorld Filter code with Servlet 2.3 model. You can find examples for wrapped request and response:

  
  

  public class CompressionResponseWrapper extends HttpServletResponseWrapper {
    protected ServletOutputStream stream = null;
    protected PrintWriter writer = null;
    protected int threshold = 0;
    protected HttpServletResponse origResponse = null;
    public CompressionResponseWrapper(HttpServletResponse response) {
  super(response);
  origResponse = response;
    }
    public void setCompressionThreshold(int threshold) {
  this.threshold = threshold;
    }
    public ServletOutputStream createOutputStream() throws IOException {
  return (new CompressionResponseStream(origResponse));
    }
    public ServletOutputStream getOutputStream() throws IOException {
  if (writer != null) {
    throw new IllegalStateException("getWriter() has already been " +
                                    "called for this response");
  }
  if (stream == null) {
    stream = createOutputStream();
  }
  ((CompressionResponseStream) stream).setCommit(true);
  ((CompressionResponseStream) stream).setBuffer(threshold);
  return stream;
    }
    public PrintWriter getWriter() throws IOException {
  if (writer != null) {
    return writer;
  }
  if (stream != null) {
    throw new IllegalStateException("getOutputStream() has already " +
                                    "been called for this response");
  }
  stream = createOutputStream();
  ((CompressionResponseStream) stream).setCommit(true);
  ((CompressionResponseStream) stream).setBuffer(threshold);
  writer = new PrintWriter(stream);
  return writer;
    }
  }
  




• public class MultipartWrapper extends HttpServletRequestWrapper {
    MultipartRequest mreq = null;
    public MultipartWrapper(HttpServletRequest req, String dir)
                                   throws IOException {
  super(req);
  mreq = new MultipartRequest(req, dir);
    }
    // Methods to replace HSR methods
    public Enumeration getParameterNames() {
  return mreq.getParameterNames();
    }
    public String getParameter(String name) {
  return mreq.getParameter(name);
    }
    public String[] getParameterValues(String name) {
  return mreq.getParameterValues(name);
    }
    public Map getParameterMap() {
  Map map = new HashMap();
  Enumeration enum = getParameterNames();
  while (enum.hasMoreElements()) {
    String name = (String) enum.nextElement();
    map.put(name, mreq.getParameterValues(name));
  }
  return map;
    }
    // Methods only in MultipartRequest
    public Enumeration getFileNames() {
  return mreq.getFileNames();
    }
    public String getFilesystemName(String name) {
  return mreq.getFilesystemName(name);
    }
    public String getContentType(String name) {
  return mreq.getContentType(name);
    }
    public File getFile(String name) {
  return mreq.getFile(name);
    }
  }
  




代码有点陈旧（2001年6月！），但它很好地证明了用法。

The code is a bit old (june 2001!), but it demonstrate the usage well.

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