Spring MVC 4:“应用程序/json"内容类型设置不正确 [英] Spring MVC 4: "application/json" Content Type is not being set correctly
问题描述
我有一个映射有以下注释的控制器:
I have a controller mapped with the following annotation:
@RequestMapping(value = "/json", method = RequestMethod.GET, produces = "application/json")
@ResponseBody
public String bar() {
return "{"test": "jsonResponseExample"}";
}
我返回了一个有效的 JSON 字符串,但是,当我在浏览器中的 Chrome Dev Tools 上查看响应时,内容类型不是 application/json
而只是普通的 text/html
.为什么没有设置内容类型?
I return a valid JSON string however, the content-type when I view the response on Chrome Dev Tools in browser is not application/json
but just plain text/html
. Why is the content type not being set?
我的web.xml
:
<?xml version="1.0" encoding="UTF-8"?>
<web-app metadata-complete="true" version="3.0"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<display-name>Spring MVC Web Application</display-name>
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<!-- static assets -->
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.js</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.css</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/dispatcher-servlet.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
</web-app>
我的dispatcher-servlet.xml
:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.1.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.1.xsd">
<context:annotation-config />
<context:component-scan base-package="com.mydomain.controllers" />
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/" />
<property name="suffix" value=".jsp" />
</bean>
</beans>
使用 WildFly 8.1 作为我的应用服务器.
Using WildFly 8.1 as my app server.
推荐答案
首先要了解的是 RequestMapping#produces()
元素在
First thing to understand is that the RequestMapping#produces()
element in
@RequestMapping(value = "/json", method = RequestMethod.GET, produces = "application/json")
仅用于限制请求处理程序的映射.它什么都不做.
serves only to restrict the mapping for your request handlers. It does nothing else.
然后,假设您的方法的返回类型为 String
并使用 @ResponseBody
进行注释,则返回值将由 StringHttpMessageConverter
它将 Content-type
标头设置为 text/plain
.如果你想自己返回一个JSON字符串并将头部设置为application/json
,使用ResponseEntity
的返回类型(去掉@ResponseBody
>) 并为其添加适当的标题.
Then, given that your method has a return type of String
and is annotated with @ResponseBody
, the return value will be handled by StringHttpMessageConverter
which sets the Content-type
header to text/plain
. If you want to return a JSON string yourself and set the header to application/json
, use a return type of ResponseEntity
(get rid of @ResponseBody
) and add appropriate headers to it.
@RequestMapping(value = "/json", method = RequestMethod.GET, produces = "application/json")
public ResponseEntity<String> bar() {
final HttpHeaders httpHeaders= new HttpHeaders();
httpHeaders.setContentType(MediaType.APPLICATION_JSON);
return new ResponseEntity<String>("{"test": "jsonResponseExample"}", httpHeaders, HttpStatus.OK);
}
<小时>
请注意,您可能应该拥有
Note that you should probably have
<mvc:annotation-driven />
在您的 servlet 上下文配置中,使用最合适的默认值设置您的 MVC 配置.
in your servlet context configuration to set up your MVC configuration with the most suitable defaults.
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