blocks|key|363447|text|您可以将Output+Stream或Writer作为控制器方法的参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|363448|@RequestMapping(method+=+RequestMethod.POST)
public+void+getJson(Writer+responseWriter)+{
++++JSONObject+rootJson+=+new+JSONObject();
++++rootJson.write(responseWriter);
}|code-block|syntax|javascript|363449|@查看Spring+Reference+Documentation+3.1+Chapter+16.3.3.1+Supported+method+argument+types|offset|length|363450|附注：我觉得在测试中使用OutputStream或Writer作为参数仍然比使用HttpServletResponse容易得多-感谢您对what+I+have+written的关注;-)|style|CODE|363451|entityMap|0|LINK|mutability|MUTABLE|url|http://static.springsource.org/spring/docs/3.1.x/spring-framework-reference/html/mvc.html#mvc-ann-arguments|1|https://stackoverflow.com/a/13120104/280244^0|0|0|3|2B|0|0|C|C|P|6|14|J|1W|J|1|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@$I|11|J|12|1|13]]|A|$]]|$1|K|3|L|5|6|7|14|8|@$I|15|J|16|M|N]|$I|17|J|18|M|N]|$I|19|J|1A|M|N]]|9|@$I|1B|J|1C|1|1D]]|A|$]]|$1|O|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]|W|$5|R|S|T|A|$U|X]]]]

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

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

@see <a href="http://static.springsource.org/spring/docs/3.1.x/spring-framework-reference/html/mvc.html#mvc-ann-arguments" rel="noreferrer">Spring Reference Documentation 3.1 Chapter 16.3.3.1 Supported method argument types</a>

p.s. I feel that using <code>OutputStream</code> or <code>Writer</code> as an parameter is still much more easier to use in tests than a <code>HttpServletResponse</code> - and thanks for paying attention to <a href="https://stackoverflow.com/a/13120104/280244">what I have written</a> ;-)

blocks|key|145319|text|最后，我为此编写了一个HttpMessageConverter。使用它，我可以执行以下操作：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|145320|@RequestMapping(method+=+RequestMethod.POST)
@ResponseBody
public+JSONObject+getJson()
++++throws+JSONException
{
++++JSONObject+rootJson+=+new+JSONObject();

++++//+Populate+JSON

++++return+rootJson;
}|code-block|syntax|javascript|145321|下面是我的HttpMessageConverter类：|145322|package+com.example;

import+java.io.IOException;
import+java.io.OutputStreamWriter;
import+java.io.PrintWriter;
import+java.nio.charset.Charset;
import+org.json.JSONException;
import+org.json.JSONObject;
import+org.springframework.http.HttpInputMessage;
import+org.springframework.http.HttpMessage;
import+org.springframework.http.HttpOutputMessage;
import+org.springframework.http.MediaType;
import+org.springframework.http.converter.AbstractHttpMessageConverter;
import+org.springframework.http.converter.HttpMessageNotReadableException;
import+org.springframework.http.converter.HttpMessageNotWritableException;

public+class+JsonObjectHttpMessageConverter
++++extends+AbstractHttpMessageConverter<JSONObject>
{
++++private+static+final+Charset+DEFAULT_CHARSET+=+Charset.forName("UTF-8");

++++public+JsonObjectHttpMessageConverter()
++++{
++++++++super(new+MediaType("application",+"json"),+new+MediaType("text",+"javascript"));
++++}

++++@Override
++++protected+boolean+supports(Class<?>+clazz)
++++{
++++++++return+JSONObject.class.equals(clazz);
++++}

++++@Override
++++protected+JSONObject+readInternal(Class<?+extends+JSONObject>+clazz,
++++++++++++++++++++++++++++++++++++++HttpInputMessage++++++++++++inputMessage)
++++++++throws+IOException,
+++++++++++++++HttpMessageNotReadableException
++++{
++++++++throw+new+UnsupportedOperationException();
++++}

++++@Override
++++protected+void+writeInternal(JSONObject++++++++jsonObject,
+++++++++++++++++++++++++++++++++HttpOutputMessage+outputMessage)
++++++++throws+IOException,
+++++++++++++++HttpMessageNotWritableException
++++{
++++++++PrintWriter+writer+=+new+PrintWriter(new+OutputStreamWriter(outputMessage.getBody(),
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++getContentTypeCharset(outputMessage)));

++++++++try
++++++++{
++++++++++++jsonObject.write(writer);
++++++++++++writer.flush();
++++++++}
++++++++catch+(JSONException+e)
++++++++{
++++++++++++throw+new+HttpMessageNotWritableException(e.getMessage(),+e);
++++++++}
++++}

++++private+Charset+getContentTypeCharset(HttpMessage+message)
++++{
++++++++MediaType+contentType+=+message.getHeaders().getContentType();

++++++++Charset+charset+=+(contentType+!=+null)+?+contentType.getCharSet()+:+null;

++++++++return+(charset+!=+null)+?+charset+:+DEFAULT_CHARSET;
++++}
}|145323|HttpMessageConverter必须注册到Spring.这可以在dispatcher-servlet.xml文件中完成，如下所示：|145324|<beans+...>

++++...++++

++++<mvc:annotation-driven+conversion-service="conversionService"+validator="validator">
++++++++<mvc:argument-resolvers>
++++++++++++...
++++++++</mvc:argument-resolvers>
++++++++<mvc:message-converters>
++++++++++++<bean+class="org.springframework.http.converter.StringHttpMessageConverter">
++++++++++++++++<property+name="supportedMediaTypes">
++++++++++++++++++++<list>
++++++++++++++++++++++++<value>text/plain;charset=UTF-8</value>
++++++++++++++++++++++++<value>application/json;charset=UTF-8</value>
++++++++++++++++++++++++<value>*/*</value>
++++++++++++++++++++</list>
++++++++++++++++</property>
++++++++++++++++<property+name="writeAcceptCharset"+value="false"+/>
++++++++++++</bean>
++++++++++++<bean+class="com.example.JsonObjectHttpMessageConverter"+/>
++++++++++++<bean+class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
++++++++++++++++<property+name="objectMapper"+ref="jacksonObjectMapper"+/>
++++++++++++</bean>
++++++++</mvc:message-converters>
++++</mvc:annotation-driven>

++++...

</beans>|145325|如您所见，我还注册了其他HttpMessageConverter对象。顺序确实很重要。|145326|entityMap^0|B|K|0|0|5|K|0|0|0|K|10|M|0|0|C|K|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|H|7|19|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|1A|8|@$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1D|8|@]|D|@]|E|$]]]|V|$]]

In the end, I wrote an <code>HttpMessageConverter</code> for this. With it, I can do the following:

<pre><code>@RequestMapping(method = RequestMethod.POST)
@ResponseBody
public JSONObject getJson()
 throws JSONException
{
 JSONObject rootJson = new JSONObject();

 // Populate JSON

 return rootJson;
}
</code></pre>

Here is my <code>HttpMessageConverter</code> class:

<pre><code>package com.example;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.nio.charset.Charset;
import org.json.JSONException;
import org.json.JSONObject;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;

public class JsonObjectHttpMessageConverter
 extends AbstractHttpMessageConverter&lt;JSONObject&gt;
{
 private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");

 public JsonObjectHttpMessageConverter()
 {
 super(new MediaType("application", "json"), new MediaType("text", "javascript"));
 }

 @Override
 protected boolean supports(Class&lt;?&gt; clazz)
 {
 return JSONObject.class.equals(clazz);
 }

 @Override
 protected JSONObject readInternal(Class&lt;? extends JSONObject&gt; clazz,
 HttpInputMessage inputMessage)
 throws IOException,
 HttpMessageNotReadableException
 {
 throw new UnsupportedOperationException();
 }

 @Override
 protected void writeInternal(JSONObject jsonObject,
 HttpOutputMessage outputMessage)
 throws IOException,
 HttpMessageNotWritableException
 {
 PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputMessage.getBody(),
 getContentTypeCharset(outputMessage)));

 try
 {
 jsonObject.write(writer);
 writer.flush();
 }
 catch (JSONException e)
 {
 throw new HttpMessageNotWritableException(e.getMessage(), e);
 }
 }

 private Charset getContentTypeCharset(HttpMessage message)
 {
 MediaType contentType = message.getHeaders().getContentType();

 Charset charset = (contentType != null) ? contentType.getCharSet() : null;

 return (charset != null) ? charset : DEFAULT_CHARSET;
 }
}
</code></pre>

The <code>HttpMessageConverter</code> must be registered with Spring. This can be done in the <code>dispatcher-servlet.xml</code> file like this:

<pre><code>&lt;beans ...&gt;

 ... 

 &lt;mvc:annotation-driven conversion-service="conversionService" validator="validator"&gt;
 &lt;mvc:argument-resolvers&gt;
 ...
 &lt;/mvc:argument-resolvers&gt;
 &lt;mvc:message-converters&gt;
 &lt;bean class="org.springframework.http.converter.StringHttpMessageConverter"&gt;
 &lt;property name="supportedMediaTypes"&gt;
 &lt;list&gt;
 &lt;value&gt;text/plain;charset=UTF-8&lt;/value&gt;
 &lt;value&gt;application/json;charset=UTF-8&lt;/value&gt;
 &lt;value&gt;*/*&lt;/value&gt;
 &lt;/list&gt;
 &lt;/property&gt;
 &lt;property name="writeAcceptCharset" value="false" /&gt;
 &lt;/bean&gt;
 &lt;bean class="com.example.JsonObjectHttpMessageConverter" /&gt;
 &lt;bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"&gt;
 &lt;property name="objectMapper" ref="jacksonObjectMapper" /&gt;
 &lt;/bean&gt;
 &lt;/mvc:message-converters&gt;
 &lt;/mvc:annotation-driven&gt;

 ...

&lt;/beans&gt;
</code></pre>

As you can see, I have other <code>HttpMessageConverter</code> objects registered too. The order does matter.

blocks|key|145339|text|请注意，如果您使用OutputStream或Writer，则需要您自己编写标头。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|145340|一种解决方法是使用InputStreamResource/ResourceHttpMessageConverter|145341|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Note that if you use the OutputStream or Writer it requires you to write the headers yourself.

One workaround is to use InputStreamResource/ResourceHttpMessageConverter

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.

I could do the following:

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

 // Populate JSON

 return rootJson.toString();
}
</code></pre>

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

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

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

 // Populate JSON

 rootJson.write(response.getWriter());
}
</code></pre>

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

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

Stream directly to response output stream in handler method of Spring MVC 3.1 controller

JSON

我有一个处理ajax调用和返回JSON的控制器方法。我使用来自json.org的JSON库来创建JSON。我可以执行以下操作：@RequestMapping(method = RequestMethod.POST)@ResponseBodypublic String getJson(){    JSONObject r...

问在Spring MVC 3.1控制器的处理方法中，直接将流转换为响应输出流
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