/**
 * Copy response body data (the entity) from the proxy to the servlet client.
 * TODO: CACHE entity here for retrieval in filter
 */
protected void copyResponseEntity( HttpResponse proxyResponse, HttpServletResponse servletResponse,
        HttpRequest proxyRequest, HttpServletRequest servletRequest ) throws IOException
{
    HttpEntity entity = proxyResponse.getEntity();
    if ( entity != null )
    {
        String key =  getCurrentUrlFromRequest( servletRequest );  // 1
        basicCache.getCache().put( key, proxyResponse.getEntity() ); // 2
        OutputStream servletOutputStream = servletResponse.getOutputStream();
        entity.writeTo( servletOutputStream );
    }
}

private FilterConfig filterConfig;

@Autowired BasicCache basicCache;


@Override
public void doFilter( ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain )
        throws IOException, ServletException
{
    String url = getCurrentUrlFromRequest( servletRequest ); // 1
    HttpEntity page = (HttpEntity) basicCache.getCache().get( url ); //2
    if ( null != page )  // 3
    {
        OutputStream servletOutputStream = servletResponse.getOutputStream();  // 4
        page.writeTo( servletOutputStream );  // 5 stream closed :(
    }
    else
    {
        filterChain.doFilter( servletRequest, servletResponse );
    }

}


public String getCurrentUrlFromRequest( ServletRequest request )
{
    if ( !( request instanceof HttpServletRequest ) ) return null;

    return getCurrentUrlFromRequest( (HttpServletRequest) request );
}

public String getCurrentUrlFromRequest( HttpServletRequest request )
{
    StringBuffer requestURL = request.getRequestURL();
    String queryString = request.getQueryString();

    if ( queryString == null ) return requestURL.toString();

    return requestURL.append( '?' ).append( queryString ).toString();
}

@Override
public void destroy()
{
}

@Override
public void init( FilterConfig filterConfig ) throws ServletException
{
    this.filterConfig = filterConfig;
}

private UserManagedCache<String, HttpEntity> userManagedCache;

public BasicCache()
{
    userManagedCache = UserManagedCacheBuilder.newUserManagedCacheBuilder( String.class, HttpEntity.class )
            .build( true );
}

public UserManagedCache getCache()
{
    return userManagedCache;
}

public void destroy()
{
    if ( null != userManagedCache )
    {
        userManagedCache.close();
    }
}