Spring MVC 的消息轉換器的作用：在 HTTP 請求/響應與 Java 對象之間進行轉換

可以自行擴展消息轉換器

一、創建對象映射規則

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;/*** 對象映射器:基于jackson將Java對象轉為json，或者將json轉為Java對象* 將JSON解析為Java對象的過程稱為 [從JSON反序列化Java對象]* 從Java對象生成JSON的過程稱為 [序列化Java對象到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();//收到未知屬性時不報異常this.configure(FAIL_ON_UNKNOWN_PROPERTIES, false);//反序列化時，屬性不存在的兼容處理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)));//注冊功能模塊 例如，可以添加自定義序列化器和反序列化器this.registerModule(simpleModule);}
}

二、擴展消息轉換器

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;/*** 配置類，注冊web層相關組件*/
@Configuration
@Slf4j
public class WebMvcConfiguration extends WebMvcConfigurationSupport {// ...// .../*** 擴展消息轉換器* 全局時間格式化* @param converters*/@Overrideprotected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {log.info("擴展消息轉換器");// 創建一個消息轉換器對象MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();// 為消息轉換器設置一個對象映射器，JacksonObjectMapper中規定了該怎樣轉換Java對象和Json數據converter.setObjectMapper(new JacksonObjectMapper());// 將自定義消息轉換器加入容器，設置優先級最高，Java對象通過網絡傳輸會執行轉換converters.add(0, converter);}
}