使用HttpServletResponseWrapper获取渲染jsp以后的html
? ?有些场景，我们会试图获取渲染jsp以后的html，或者修改一下生成json，例如把普通的json换成跨域的jsonp。
ResponseFacade只提供了getOutStream(),但是获取不了stream的容器bytearray，不通过hacker的方式根本获取不了。Tomcat也意识到这一点，提供了HttpServletResponseWrapper帮我们解决这个问题，对于HttpServletResponseWrapper有这样的comments:
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? ? ???Provides a convenient implementation of the HttpServletResponse interface
?* that can be subclassed by developers wishing to adapt the response from a
?* Servlet. This class implements the Wrapper or Decorator pattern. Methods
?* default to calling through to the wrapped response object.
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我们只要在其子类添加一些逻辑就能得到我们想要的东西,用byteArrayOutSteam换掉coyoteOutStream，再通过toByteArray就能获取到html，但这得借助filter帮我们用responsewrapper在dochain()换掉reponse,
上代码吧
/** * Creates a GenericResponseWrapper */ public GenericResponseWrapper(final HttpServletResponse response, final OutputStream outstr) { super(response); this.outstr = new FilterServletOutputStream(outstr); } /** * Gets the outputstream. */ public ServletOutputStream getOutputStream() { return outstr; } /** * Gets the print writer. */ public PrintWriter getWriter() throws IOException { if (writer == null) { writer = new PrintWriter(new OutputStreamWriter(outstr, getCharacterEncoding()), true); } return writer; } ??