? ?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:

?

? ? ???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;  
    }  

?