在Spring MVC 3.1控制器的处理程序方法中直接流式传输到响应输出流

问题描述

我有一个控制器方法来处理ajax调用并返回JSON.我正在使用json.org中的JSON库来创建JSON.

I have a controller method that handles ajax calls and returns JSON. I am using the JSON library from json.org to create the JSON.

我可以执行以下操作:

@RequestMapping(method = RequestMethod.POST)
@ResponseBody
public String getJson()
{
    JSONObject rootJson = new JSONObject();

    // Populate JSON

    return rootJson.toString();
}

但是将JSON字符串组合在一起效率很低，只是让Spring将其写入响应的输出流中.

But it is inefficient to put together the JSON string, only to have Spring write it to the response's output stream.

相反，我可以将其直接写到响应输出流中，如下所示:

Instead, I can write it directly to the response output stream like this:

@RequestMapping(method = RequestMethod.POST)
public void getJson(HttpServletResponse response)
{
    JSONObject rootJson = new JSONObject();

    // Populate JSON

    rootJson.write(response.getWriter());
}

但是，似乎有比通过将HttpServletResponse传递到处理程序方法更好的方法了.

But it seems like there would be a better way to do this than having to resort to passing the HttpServletResponse into the handler method.

是否可以从我可以使用的处理程序方法中返回另一个类或接口以及@ResponseBody批注?

Is there another class or interface that can be returned from the handler method that I can use, along with the @ResponseBody annotation?

推荐答案

您可以将Output Stream或Writer作为控制器方法的参数.

You can have the Output Stream or the Writer as an parameter of your controller method.

@RequestMapping(method = RequestMethod.POST)
public void getJson(Writer responseWriter) {
    JSONObject rootJson = new JSONObject();
    rootJson.write(responseWriter);
}

@请参见 Spring参考文档3.1第16.3.3.1章支持的方法参数类型

p.s.我觉得在测试中使用OutputStream或Writer作为参数仍然比HttpServletResponse更容易使用-感谢您关注;-)

p.s. I feel that using OutputStream or Writer as an parameter is still much more easier to use in tests than a HttpServletResponse - and thanks for paying attention to what I have written ;-)

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