writer 是否需要在 render 方法里就 close 掉?

Question

下面是FreeMarkerRender.java 里的代码:

public void render() {
		response.setContentType(contentType);
        Enumeration<String> attrs = request.getAttributeNames();
		Map root = new HashMap();
		while (attrs.hasMoreElements()) {
			String attrName = attrs.nextElement();
			root.put(attrName, request.getAttribute(attrName));
		}
		
		PrintWriter writer = null;
        try {
			Template template = config.getTemplate(view);
			writer = response.getWriter();
			template.process(root, writer);		// Merge the data-model and the template
		} catch (Exception e) {
			throw new RenderException(e);
		}
		finally {
			if (writer != null)
				writer.close();
		}
	}

下面这段是 beetl 的WebRender.java代码:

public void render(String key, HttpServletRequest request, HttpServletResponse response, Object... args)
	{
		Writer writer = null;
		OutputStream os = null;
		try

		{
			//			response.setContentType(contentType);
			Template template = gt.getTemplate(key);
			Enumeration<String> attrs = request.getAttributeNames();

			while (attrs.hasMoreElements())
			{
				String attrName = attrs.nextElement();
				template.binding(attrName, request.getAttribute(attrName));

			}
			WebVariable webVariable = new WebVariable();
			webVariable.setRequest(request);
			webVariable.setResponse(response);
			webVariable.setSession(request.getSession());

			template.binding("session", new SessionWrapper(webVariable.getSession()));

			template.binding("servlet", webVariable);
			template.binding("request", request);
			template.binding("ctxPath", request.getContextPath());

			modifyTemplate(template, key, request, response, args);

			if (gt.getConf().isDirectByteOutput())
			{
				os = response.getOutputStream();
				template.renderTo(os);
			}
			else
			{
				writer = response.getWriter();
				template.renderTo(writer);
			}

		}
		catch (IOException e)
		{
			handleClientError(e);
		}
		catch (BeetlException e)
		{
			handleBeetlException(e);
		}

		finally
		{
			try
			{
				if (writer != null)
					writer.flush();
				if (os != null)
				{
					os.flush();
				}
			}
			catch (IOException e)
			{
				handleClientError(e);
			}
		}
	}

FreeMarkerRender里调用了 writer.close(), WebRender里面没有调用 writer.close().

-------------------------------------------------------------------------------------------

writer 是否需要在 render 方法里就 close 掉?

如果 close 掉了, 我在下面的代码中就没办法写入数据了, 该如何处理?

public class TimeHandler extends Handler {
    @Override
    public void handle(String target, HttpServletRequest request, HttpServletResponse response, boolean[] isHandled) {
        long start = System.currentTimeMillis();
        nextHandler.handle(target, request, response, isHandled);
        long end = System.currentTimeMillis();
        Writer writer = null;
        try {
            writer = response.getWriter();
            writer.write("timehandler: " + (end - start));
        } catch (IOException e) {
        } finally {
            try {
                if (writer != null)
                    writer.flush();
            } catch (IOException e) {
            }
        }
    }
}

Answer 1

不需要close，一般web服务器，或者框架会在最后close，所以beetl render里只是flush了一下