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寻找httpservletresponsewrapper的捕获impl

servlets java

skaffman · 技术社区 · 16 年前

Javaee API附带了httpServletResponseWrapper,引用JavaDoc,“它提供了httpServletResponse接口的一个方便的实现,开发人员可以对该接口进行子类化,以适应来自servlet的响应。”在不进行子类化的情况下,该类只将所有调用传递到包装的响应对象。有一个类似的请求包装器。

有人能给我指出任何提供这些类的有用子类实现的实用程序库吗?特别是,我在寻找一个响应包装器的子类,它捕获写入的响应(作为字符串,byte[],无论什么合适的),并通过API方法公开它。

我自己写了一个相当不成熟的版本,但坦白地说,我不应该这样做,我宁愿把它扔掉,用一个现成的版本。

2 回复 | 直到 13 年前

David Rabinowitz 13 年前

我不知道任何实现,即使gzip示例只需编写到bytearrayOutputstream就可以很容易地进行改编。您还可以通过查看以下位置的其他响应包装器实现来获取想法:

SiteMesh
DWR 也使用它

原始答案:

JavaWorld有一篇经典文章 Filter code with Servlet 2.3 model . 您可以找到打包请求和响应的示例:

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);
  }
}

代码有点旧(2001年6月!)但是它很好地演示了用法。

sillydino 16 年前

在过去,我使用了Spring框架中提供的对象。尤其是,这一点应该有效: http://static.springsource.org/spring/docs/2.0.x/api/org/springframework/mock/web/MockHttpServletRequest.html