Spring MVC 的消息转换器的作用：在 HTTP 请求/响应与 Java 对象之间进行转换

可以自行扩展消息转换器

一、创建对象映射规则

package com.sky.json;import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;import static com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES;/*** 对象映射器:基于jackson将Java对象转为json，或者将json转为Java对象* 将JSON解析为Java对象的过程称为 [从JSON反序列化Java对象]* 从Java对象生成JSON的过程称为 [序列化Java对象到JSON]*/
public class JacksonObjectMapper extends ObjectMapper {public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";//public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm";public static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";public JacksonObjectMapper() {super();//收到未知属性时不报异常this.configure(FAIL_ON_UNKNOWN_PROPERTIES, false);//反序列化时，属性不存在的兼容处理this.getDeserializationConfig().withoutFeatures(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);SimpleModule simpleModule = new SimpleModule().addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT))).addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT))).addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT))).addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT))).addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT))).addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));//注册功能模块 例如，可以添加自定义序列化器和反序列化器this.registerModule(simpleModule);}
}

二、扩展消息转换器

package com.sky.config;import com.sky.interceptor.JwtTokenAdminInterceptor;
import com.sky.json.JacksonObjectMapper;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;import java.util.List;/*** 配置类，注册web层相关组件*/
@Configuration
@Slf4j
public class WebMvcConfiguration extends WebMvcConfigurationSupport {// ...// .../*** 扩展消息转换器* 全局时间格式化* @param converters*/@Overrideprotected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {log.info("扩展消息转换器");// 创建一个消息转换器对象MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();// 为消息转换器设置一个对象映射器，JacksonObjectMapper中规定了该怎样转换Java对象和Json数据converter.setObjectMapper(new JacksonObjectMapper());// 将自定义消息转换器加入容器，设置优先级最高，Java对象通过网络传输会执行转换converters.add(0, converter);}
}