resource editing filter

ResourceFilter.java

package wrm.web.filter;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.HashMap;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

/**
 * Servlet Filter implementation class ResourceFilter
 */
public class ResourceFilter implements Filter {

	HashMap<String, String> cache = new HashMap<String, String>();
	HashMap<String, String> resType = new HashMap<String, String>();

	/**
	 * Default constructor.
	 */
	public ResourceFilter() {
		// TODO Auto-generated constructor stub
	}

	/**
	 * @see Filter#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
	}

	/**
	 * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
	 */
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		// rewrite it to normal url:
		HttpServletRequest req = (HttpServletRequest) request;

		HttpServletRequest reqWrapper = new HttpServletRequestWrapper(req) {
			@Override
			public String getHeader(String name) {
				if (name.equals("If-None-Match")) // disable caching
					return null;

				return super.getHeader(name);
			}

			@Override
			public long getDateHeader(String name) {
				if (name.equals("If-Modified-Since"))
					return -1;

				return super.getDateHeader(name);
			}

		};

		String url = req.getRequestURI();

		if (req.getMethod().equals("POST")
				&& "overwrite".equals(req.getQueryString())) {

			// String content = readAll(req.getReader());
			String content = req.getParameter("content");

			cache.put(url, content);
			((HttpServletResponse) response).sendRedirect(url + "?edit");
			return;
		}

		final ByteArrayOutputStream baos = new ByteArrayOutputStream();
		final PrintWriter w = new PrintWriter(new OutputStreamWriter(baos,
				"UTF-8"));

		HttpServletResponse httpRes = (HttpServletResponse) response;
		HttpServletResponse resWrapper = new HttpServletResponseWrapper(httpRes) {

			@Override
			public ServletOutputStream getOutputStream() throws IOException {
				return new ServletOutputStream() {

					@Override
					public void write(int b) throws IOException {
						baos.write(b);
					}
				};
			}

			@Override
			public PrintWriter getWriter() throws IOException {
				return w;
			}

			@Override
			public void setContentLength(int len) {
				// super.setContentLength(len);
			}

			@Override
			public void setStatus(int sc) {
				// TODO Auto-generated method stub
				// super.setStatus(sc);
			}
		};

		
		
		if (cache.containsKey(url)) {
			System.out.println("Providing cache-edited version of "  + url);
			ServletResponse outRes = "edit".equals(req.getQueryString()) ? resWrapper :  response;
			outRes.getWriter().write(cache.get(url));
			if (resType.containsKey(url))
				httpRes.setContentType(resType.get(url));
		} else
		{
			// pass the request along the filter chain
			chain.doFilter(reqWrapper, "edit".equals(req.getQueryString()) ? resWrapper : response);
			resType.put(url, httpRes.getContentType());
		}
		
		w.flush();

		
		
		if ("edit".equals(req.getQueryString())) {
			// load template
			InputStream stream = getClass().getResourceAsStream(
					"/wrm/web/filter/template.html");
			if (stream == null) {
				throw new ServletException("Cannot find template");
			}

			String template = convertStreamToString(stream);
			template = simpleformat(template, url + "?overwrite",
					baos.toString(), getMode(url), getEditedList());

			response.getWriter().write(template);

			httpRes.setContentType("text/html");

		} 
//		else
//			response.getWriter().write(baos.toString());

		httpRes.setStatus(200);
		httpRes.flushBuffer();
	}

	private String getEditedList() {
		String list = "";
		for (String uri : cache.keySet())
			list += "<option>" + uri + "</option>\n";
		return list;
	}

	private String getMode(String url) {
		if (url.endsWith(".js"))
			return "javascript";

		if (url.endsWith("html")) // xhtml, html
			return "html";

		if (url.endsWith("xml")) // xhtml, html
			return "xml";

		if (url.endsWith("css"))
			return "css";

		return "plain";
	}

	private String simpleformat(String template, String... args) {
		for (int i = 0; i < args.length; ++i) {
			template = template.replace("{" + i + "}", args[i]);
		}
		return template;
	}

	private String readAll(BufferedReader reader) {
		StringBuffer buf = new StringBuffer();

		String currentLine = null;
		try {
			while ((currentLine = reader.readLine()) != null) {
				buf.append(currentLine + "\n");

			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		return buf.toString();
	}

	/**
	 * @see Filter#init(FilterConfig)
	 */
	public void init(FilterConfig fConfig) throws ServletException {
		// TODO Auto-generated method stub
	}

	public static String convertStreamToString(InputStream is) {
		BufferedReader reader = new BufferedReader(new InputStreamReader(is));
		StringBuilder sb = new StringBuilder();
		String line = null;
		try {
			while ((line = reader.readLine()) != null) {
				sb.append(line + "\n");
			}
			is.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return sb.toString();
	}
}

template.html

<html lang="en">
<head>
<title>Cache Resource Editor</title>
<style type="text/css" media="screen">
    #editor {
        position: absolute;
        top: 25px;
        bottom: 0;
        right: 0;
        left: 0;
    }
   #send{
        position: absolute;
        top: 0;
        left: 0;
    }
    
    #content {
    display:none;
    }
</style>
</head>
<body>

<div id="editor"></div>
     
    
    <div id="send">  
     <form id="form" action="{0}" method="post">
         <button
         onclick="save()">Send</button>
         Cache Resource Editor by wrm
         <span style="width:100px;display:inline-block">&nbsp;</span>
         Edited:<select id="edits" name="edits" size="1" onchange="window.location.href=this.options[this.selectedIndex].value + '?edit'">
		      <option>Jump to</option>
		      {3}
		   </select>
         <textarea id="content" name="content" >{1}</textarea>
     </form>
    </div>     
    
<script src="http://d1n0x3qji82z53.cloudfront.net/src-min-noconflict/ace.js" type="text/javascript" charset="utf-8"></script>
<script>
	
	function save(){
		document.getElementById('content').value = editor.getValue();
		document.forms[0].submit();
	};
    editor = ace.edit("editor");
    
    
    editor.commands.addCommand({
        name: 'save',
        bindKey: {win: 'Ctrl-S',  mac: 'Command-S'},
        exec: function(editor) {
           save();
        }
    });
    
    
    
    
    editor.setTheme("ace/theme/monokai");
    editor.getSession().setValue(document.getElementById("content").value);
    editor.getSession().setMode("ace/mode/{2}");
</script>
</body>
</html>