Spring @ResponseBody 返回乱码 的优雅解决办法

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目录(?)[+]

返回的结果中，中文全部被问号（?）代替的解决办法：

*-servlet.xml的部分配置如下：

<bean id="utf8Charset" class="java.nio.charset.Charset"
        factory-method="forName">
        <constructor-arg value="UTF-8"/>
    </bean>

    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <constructor-arg ref="utf8Charset" />
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

思路非常简单：查看StringHttpMessageConverter可知其有两个构造函数，

public StringHttpMessageConverter() {
    this(DEFAULT_CHARSET);
}

public StringHttpMessageConverter(Charset defaultCharset) {
    super(new MediaType("text", "plain", defaultCharset), MediaType.ALL);
    this.defaultCharset = defaultCharset;
    this.availableCharsets = new ArrayList<Charset>(Charset.availableCharsets().values());
}

这里采用第二个构造函数向其中注入我们的utf8Charset


上面配置会覆盖 mvc:annotation-driven 默认配置的StringHttpMessageConverter，其余的MessageConverter应该不会受到影响。

具体文档描述如下：

Element : message-converters
Configures one or more HttpMessageConverter types to use for converting @RequestBody method parameters and
 @ResponseBody method return values. Using this configuration element is optional. HttpMessageConverter
 registrations provided here will take precedence over HttpMessageConverter types registered by default. Also see
 the register-defaults attribute if you want to turn off default registrations entirely.

<mvc:annotation-driven>会默认配置一些HttpMessageConverter，Spring Reference描述如下：

HttpMessageConverter support for @RequestBody method parameters and @ResponseBody method return values from @RequestMapping or @ExceptionHandler methods.
This is the complete list of HttpMessageConverters set up by mvc:annotation-driven:
ByteArrayHttpMessageConverter converts byte arrays.
StringHttpMessageConverter converts strings.
ResourceHttpMessageConverter converts to/from org.springframework.core.io.Resource for all media types.
SourceHttpMessageConverter converts to/from a javax.xml.transform.Source.
FormHttpMessageConverter converts form data to/from a MultiValueMap<String, String>.
Jaxb2RootElementHttpMessageConverter converts Java objects to/from XML — added if JAXB2 is present on the classpath.
MappingJackson2HttpMessageConverter (or MappingJacksonHttpMessageConverter) converts to/from JSON — added if Jackson 2 (or Jackson) is present on the classpath.
AtomFeedHttpMessageConverter converts Atom feeds — added if Rome is present on the classpath.
RssChannelHttpMessageConverter converts RSS feeds — added if Rome is present on the classpath.

返回的结果中，中文全部是乱码（非问号）的解决办法：

在web.xml中加入以下Filter：

<filter>
        <filter-name>encodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>

    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>