方法一:最安全做法使用bean替代默认转换器方法

写法一

@Configuration
public class MyConfiguration {
    @Bean
    public HttpMessageConverters customConverters() {
        List<HttpMessageConverters> converters = new ArrayList<>();
        // 1、需要先定义一个convert转换消息的对象；
        FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
        // 2、添加fastjson的配置信息，比如 是否要格式化返回json数据
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat);
        // 3、在convert中添加配置信息.
        fastConverter.setFastJsonConfig(fastJsonConfig);
        // 4、将convert添加到converters当中.
        converters.add(fastConverter);
        return new HttpMessageConverters(true, converters);
    }

}

　　//写法二

@Configuration
public class FastJsonHttpMessageConfig {
	@Bean
	public HttpMessageConverters fastJsonHttpMessageConverters() {
		FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();

		FastJsonConfig fastJsonConfig = new FastJsonConfig();
		fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue,
				SerializerFeature.WriteNullListAsEmpty, SerializerFeature.WriteNullStringAsEmpty,
				SerializerFeature.WriteNullNumberAsZero, SerializerFeature.WriteNullBooleanAsFalse);

		fastJsonConfig.setFeatures(Feature.OrderedField);
		List<MediaType> fastMedisTypes = new ArrayList<>();
		fastMedisTypes.add(MediaType.APPLICATION_JSON_UTF8);
		fastConverter.setSupportedMediaTypes(fastMedisTypes);

		fastConverter.setFastJsonConfig(fastJsonConfig);
		HttpMessageConverter<?> converter = fastConverter;
		return new HttpMessageConverters(converter);
	}
}

　　方法二

　　第三种实现父类,缺点很明显，完全接管的springmvc，默认配置全部失效，需要重新自己配置

@Configuration
public class SpringMvcConfigure extends WebMvcConfigurationSupport{

    /**
     * 配置消息转换器
     * @param converters
     */
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        //自定义配置...
        FastJsonConfig config = new FastJsonConfig();
        config.setSerializerFeatures(SerializerFeature.QuoteFieldNames,
                SerializerFeature.WriteEnumUsingToString,
                /*SerializerFeature.WriteMapNullValue,*/
                SerializerFeature.WriteDateUseDateFormat,
                SerializerFeature.DisableCircularReferenceDetect);
        fastJsonHttpMessageConverter.setFastJsonConfig(config);
        converters.add(fastJsonHttpMessageConverter);
        supper.configureMessageConverters(converters);
    }
}