SpringBoot基于jackson对象映射器扩展mvc框架的消息转换器

在SpringBoot中，可以基于jackson对象映射器扩展mvc框架的消息转换器
具体步骤如下：
1、创建对象映射器：

package com.java.demo.common;import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
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.math.BigInteger;
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_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().addSerializer(BigInteger.class, ToStringSerializer.instance) // 将BigInt类型转换为字符串类型.addSerializer(Long.class, ToStringSerializer.instance) // 将Long类型转换为字符串类型// 将LocalDateTime转换成对应格式.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);}
}

2、扩展MVC框架的消息转换器

package com.java.demo.config;import com.itheima.reggie.common.JacksonObjectMapper;
import lombok.extern.slf4j.Slf4j;
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.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;import java.util.List;@Slf4j
@Configuration
public class WebMvcConfig extends WebMvcConfigurationSupport {/*** 设置静态资源映射* @param registry*/protected void addResourceHandlers (ResourceHandlerRegistry registry) {log.info("进行静态资源映射");registry.addResourceHandler("/backend/**").addResourceLocations("classpath:/backend/");registry.addResourceHandler("/front/**").addResourceLocations("classpath:/front/");}/*** 扩展mvc框架的消息转换器* @param converters 消息转换器*/@Overrideprotected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {log.info("消息转换器");// 创建一个消息转换器MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();// 设置对象转换器，底层使用Jackson将Java对象转为jsonmessageConverter.setObjectMapper(new JacksonObjectMapper());// 将上面的消息转换器对象追加到mvc框架的转换器集合中，并将自定义的转换器置为第一位converters.add(0, messageConverter);
//        super.extendMessageConverters(converters);}
}