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
*/
@Override
protected void extendMessageConverters(List> 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json
messageConverter.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);
}
}