我有一个映射有以下注释的控制器:
@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唯一的text/html。为什么未设置内容类型?
application/json
text/html
我的web.xml:
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:
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。
要了解的第一件事是,RequestMapping#produces()在元素
RequestMapping#produces()
@RequestMapping(value = "/json", method = RequestMethod.GET, produces = "application/json")
仅用于限制请求处理程序的映射。它什么也没做。
然后,假设你的方法的返回类型为,String并带有注释@ResponseBody,则将通过处理返回值并将StringHttpMessageConverter其设置Content-type为text/plain。如果你想自己返回JSON字符串并将标头设置为application/json,请使用返回类型ResponseEntity(摆脱@ResponseBody)并向其添加适当的标头。
String
@ResponseBody
StringHttpMessageConverter
Content-type为text/plain
ResponseEntity
@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); }
请注意,你可能应该有
<mvc:annotation-driven />
在Servlet上下文配置中使用最合适的默认设置来设置MVC配置。