尋找HttpServletResponseWrapper的捕獲impl

Question

JavaEE API附帶HttpServletResponseWrapper，引用javadoc「提供了一個方便的HttpServletResponse接口實現，該接口可以由希望修改Servlet響應的開發人員進行分類。」沒有子類，這個類只是將所有調用傳遞給包裝的響應對象。有一個類似的請求包裝。

任何人都可以指向任何提供這些類的有用子類實現的實用程序庫嗎？特別是，我正在尋找一個響應包裝器的子類，它可以捕獲寫入的響應（如適當的String，byte []），並通過API方法公開它。

我自己寫了一個相當不完整的版本，但坦率地說，我不應該，我寧願把它扔掉，並使用現成的一個。

Answer 1

我不知道任何實現，即使gzip示例可以通過只寫入一個ByteArrayOutputStream很容易適應。您也可以通過尋找其他響應包裝實施採取的想法：

• SiteMesh
• DWR也使用它

原來的答覆：

有一個在JavaWorld的經典文章Filter code with Servlet 2.3 model。你可以找到包裝的請求和示例響應：

• Compression the 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; 
      } 
  } 
  

• Handling file upload

  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); 
      } 
  } 
  

的代碼是有點老了（！2001年6月），但它很好地展示了它的用法。

Answer 2

在過去，我使用了春天框架中提供的對象。特別是，這應該工作：http://static.springsource.org/spring/docs/2.0.x/api/org/springframework/mock/web/MockHttpServletRequest.html