配置MappingJackson2HttpMessageConverter不生效

ゝ一世哀愁。 2021-11-05 08:14 1894阅读 0赞

Spring MVC 返回json数据，默认情况下日期是一长串数字，需要配置MappingJackson2HttpMessageConverter，使日期数据格式化  
![在这里插入图片描述][20190808203012355.png]

@Configuration
    @EnableWebMvc
    @ComponentScan({ "com.sky.springmvctest"})
    // WebMvcConfigurationSupport WebMvcConfigurer
    public class SpringMvcConfig extends WebMvcConfigurerAdapter { 
    	@Bean
    	public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() { 
    		MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
    		// 设置日期格式
    		ObjectMapper objectMapper = new ObjectMapper();
    		mappingJackson2HttpMessageConverter.setObjectMapper(objectMapper);
    		objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd"));
    		// 设置中文编码格式
    		List<MediaType> list = new ArrayList<MediaType>();
    		list.add(MediaType.APPLICATION_JSON_UTF8);
    		mappingJackson2HttpMessageConverter.setSupportedMediaTypes(list);
    		return mappingJackson2HttpMessageConverter;
    	}
    	省略其他配置...
    }

配置后日期依然没有格式化，查找源码发现：  
WebMvcConfigurationSupport  
protected final void addDefaultHttpMessageConverters(List<HttpMessageConverter<?>> messageConverters)

if (jackson2Present) { 
    			messageConverters.add(new MappingJackson2HttpMessageConverter(
    					Jackson2ObjectMapperBuilder.json().applicationContext(this.applicationContext).build()));
    		}
    		else if (gsonPresent) { 
    			messageConverters.add(new GsonHttpMessageConverter());
    		}

SpringMvcConfig 配置的bean没有替换messageConverters中的MappingJackson2HttpMessageConverter  
重写extendMessageConverters方法，如果存在MappingJackson2HttpMessageConverter则删掉，加入新的

@Configuration
    @EnableWebMvc
    @ComponentScan({ "com.sky.springmvctest"})
    // WebMvcConfigurationSupport WebMvcConfigurer
    public class SpringMvcConfig extends WebMvcConfigurerAdapter { 
    	@Override
    	public void extendMessageConverters(List<HttpMessageConverter<?>> converters) { 
    		for (int i = 0; i < converters.size(); i++) { 
    			HttpMessageConverter<?> messageConverter = converters.get(i);
    			if (messageConverter instanceof MappingJackson2HttpMessageConverter) { 
    				converters.remove(i);
    			}
    		}
    		converters.add(mappingJackson2HttpMessageConverter());
    	}
    	
    	@Bean
    	public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() { 
    		MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
    		// 设置日期格式
    		ObjectMapper objectMapper = new ObjectMapper();
    		mappingJackson2HttpMessageConverter.setObjectMapper(objectMapper);
    		objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd"));
    		// 设置中文编码格式
    		List<MediaType> list = new ArrayList<MediaType>();
    		list.add(MediaType.APPLICATION_JSON_UTF8);
    		mappingJackson2HttpMessageConverter.setSupportedMediaTypes(list);
    		return mappingJackson2HttpMessageConverter;
    	}
    	省略其他配置...
    }

![在这里插入图片描述][20190808204922611.png]

[20190808203012355.png]: /images/20211104/2755241809e3498cb40265203db5b27e.png
[20190808204922611.png]: /images/20211104/da4397686c39412e826928cabb99edfc.png