• springBoot项目 ObjectMapper 序列化统一格式处理

    springBoot项目 ObjectMapper 序列化统一格式处理

    1. 开篇 fastjson 与 jackson

    1.1 关于 fastjson 与 jackson 的简单使用

    1.2 关于 fastjson 序列化的全局控制

    • 非全局控制的，参考上面链接即可实现，在此不做介绍

    1.2.1 配置实现代码

    • 需要注意点：
      创建实现了 WebMvcConfigurer 接口的配置类ExternalFastJsonConfig.java，如果项目中已经有实现 WebMvcConfigurer 的接口类，可以直接把ExternalFastJsonConfig.java里的核心代码放进去即可，不用再创建
    • 如下：
      ① ExternalFastJsonConfig.java
      package com.liu.susu.common.config;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.serializer.ValueFilter;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import com.liu.susu.common.util.DateUtils;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.*;

import java.nio.charset.Charset;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * description 统一处理返回前端的json格式
 * @author susu
 **/
@Configuration
public class ExternalFastJsonConfig implements WebMvcConfigurer {

    private static final String FORMAT = "yyyy-MM-dd HH:mm:ss";

    private static SerializerFeature[] serializerFeatures = new SerializerFeature[]{
            SerializerFeature.PrettyFormat,
            SerializerFeature.WriteEnumUsingToString,
            SerializerFeature.IgnoreNonFieldGetter
    };

    private static ValueFilter filter = new ValueFilter () {

        public Object process(Object obj, String key, Object value) {
            if(value==null){
//                return "is null ???? I want to change the value!!!";
            }else if("".equals(value.toString())){
                return null;
            }
            if (value instanceof LocalDateTime){
//                return "2022-07-29 10:43:22";
                return DateUtils.getDateTimeStr((LocalDateTime)value);
            }else if (value instanceof LocalDate){
                return DateUtils.getDateStrYMD((LocalDate)value);
            }else if (value instanceof Date){
                return DateUtils.getDateStrYMD((Date)value);
            }
            return value;
        }
    };

    @Bean
    public HttpMessageConverter fastJsonHttpMessageConverters(){

        FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig config = new FastJsonConfig();

        config.setSerializerFeatures(serializerFeatures);
        config.setDateFormat(FORMAT);
        config.setSerializeFilters(filter);
        fastConverter.setFastJsonConfig(config);
        fastConverter.setDefaultCharset(Charset.forName("UTF-8"));
        List<MediaType> mediaTypeList = new ArrayList<>();
        // 解决中文乱码问题，相当于在Controller上的@RequestMapping中加了个属性produces = "application/json"
        mediaTypeList.add(MediaType.APPLICATION_JSON);
        fastConverter.setSupportedMediaTypes(mediaTypeList);
        HttpMessageConverter<?> converter=fastConverter;
        return converter;
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
//        converters.add(fastJsonHttpMessageConverters());
    }

    //解决跨域问题
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOrigins("*")
                .allowedMethods("GET", "HEAD", "POST", "PUT", "DELETE", "OPTIONS")
                .allowCredentials(true)
                .maxAge(3600)
                .allowedHeaders("*");
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
//        registry.addResourceHandler("/**").addResourceLocations(
//                "classpath:/static/");
//        registry.addResourceHandler("/doc.html").addResourceLocations(
//                "classpath:/META-INF/resources/");
//        registry.addResourceHandler("/webjars/**").addResourceLocations(
//                "classpath:/META-INF/resources/webjars/");
        registry.addResourceHandler("/**").addResourceLocations("/");
//        super.addResourceHandlers(registry);
    }


}

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    ② DateUtils.java

    • 这个简单了，自己根据需要定义即可，因为我上面用到了不用的Date类型，所以在 ValueFilter 里分别处理了一下
    • 代码如下：
      package com.liu.susu.common.util;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.Date;

/**
 * @FileName DateUtils
 * @Description
 * @Author susu
 **/
public class DateUtils {

    private static final String FORMAT_1 = "yyyy-MM-dd HH:mm:ss";
    private static final String FORMAT_2 = "yyyy-MM-dd";


    /**
     * description :把 LocalDate 类型转换成 "yyyy-MM-dd"
     * @param localDate
     * @return java.lang.String
     * @author susu
     */
    public static String getDateStrYMD(LocalDate localDate){
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(FORMAT_2);
        return dateTimeFormatter.format(localDate);
    }

    /**
     * description :如果有时分秒直接返回（时分秒是0的），如果没有返回年月日
     * @param date
     * @return java.lang.String
     * @author susu
     */
    public static String getDateStrYMD(Date date){
        LocalDateTime localDateTime = date.toInstant().atZone((ZoneId.systemDefault())).toLocalDateTime();
        if (localDateTime.getHour()==0 && localDateTime.getSecond()==0 && localDateTime.getMinute()==0){
            return getDateYMD(localDateTime);
        }
        return getDateTimeStr(localDateTime);
    }

    /**
     * description :把 LocalDateTime 类型转换成 "yyyy-MM-dd"
     * @param localDateTime
     * @return java.lang.String
     * @author susu
     */
    public static String getDateYMD(LocalDateTime localDateTime){
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(FORMAT_2);
        return dateTimeFormatter.format(localDateTime);
    }

    /**
     * description :把 LocalDateTime 类型转换成 "yyyy-MM-dd HH:mm:ss"
     * @param localDateTime
     * @return java.lang.String
     * @author susu
     */
    public static String getDateTimeStr(LocalDateTime localDateTime){
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(FORMAT_1);
        return dateTimeFormatter.format(localDateTime);
    }


}


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    1.2.2 存在的问题

    • 对于枚举的序列化不是很好用，我这边没有实现，如果有更好的方法，欢迎沟通交流

    • 枚举序列化 MyEnumSerializer .java

      package com.liu.susu.common;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;

import java.io.IOException;


/**
 * description
 * @author susu
 * @date 2022-08-12
 **/
public class MyEnumSerializer extends JsonSerializer<MyEnum> {

    @Override
    public void serialize(MyEnum value, JsonGenerator gen, SerializerProvider serializers) throws IOException {

        gen.writeStartObject();
        gen.writeFieldName("value");
        gen.writeString(value.getValue().toString());
        gen.writeFieldName("name");
        gen.writeString(value.getName());
        gen.writeEndObject();

    }
}


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      • MyEnum.java
      public interface MyEnum<E extends Enum<?>, T>  {
    Object getValue();
    String getName();
}

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    • 使用方式
      方式1：在实体的属性上加注解：

      @JSONField(serializeUsing = MyEnumSerializer.class)

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      方式2：在 MyEnum 上加注解：

      @JSONType(serializer = MyEnumSerializer.class)

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      但是，验证试了一下，这两种方式都没有实现，具体怎么实现，或者是枚举序列化类有问题？我没再试，直接换了jackson，大家也可以参考下面一篇文章试试
      fastjson枚举转换（序列化、反序列化）最新版本爬坑记录.

    1.3 关于 jackson 序列化的全局控制

    1.3.1 配置类代码

    • ExternalJacksonConfig.java
      package com.liu.susu.common.config;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.*;
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 org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.HashMap;
import java.util.Map;

/**
 * description 统一处理返回前端的json格式
 * @author susu
 **/
@Configuration
public class ExternalJacksonConfig {

    private static final String FORMAT = "yyyy-MM-dd HH:mm:ss";
    private static final DateTimeFormatter FORMAT_YMD_TIME = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    private static final DateTimeFormatter FORMAT_YMD = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    private static final DateTimeFormatter FORMAT_TIME = DateTimeFormatter.ofPattern("HH:mm:ss");

    @Bean
    @Primary
    @ConditionalOnMissingBean(ObjectMapper.class)
    public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        objectMapper.setDateFormat(new SimpleDateFormat(FORMAT));
        objectMapper.configure(MapperFeature.AUTO_DETECT_IS_GETTERS,false);
        objectMapper.configure(SerializationFeature.WRITE_ENUMS_USING_TO_STRING,true);
        //反序列化时
        objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);//允许出现特殊字符和转义符、
        objectMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);//允许出现单引号


        objectMapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {
            @Override
            public void serialize(Object object, JsonGenerator value, SerializerProvider serializerProvider) throws IOException {
                value.writeString("");
            }
        });

        return objectMapper;
    }


    /**
     * 处理 LocalDateTime LocalDate 的序列化和反序列化
     * @return
     */
    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {
        Map<Class<?>, JsonSerializer<?>> serializers = new HashMap<>();
        serializers.put(LocalDateTime.class, new LocalDateTimeSerializer(FORMAT_YMD_TIME));
        serializers.put(LocalDate.class, new LocalDateSerializer(FORMAT_YMD));
        serializers.put(LocalTime.class, new LocalTimeSerializer(FORMAT_TIME));

        Map<Class<?>, JsonDeserializer<?>> deserializers = new HashMap<>();
        deserializers.put(LocalDateTime.class, new LocalDateTimeDeserializer(FORMAT_YMD_TIME));
        deserializers.put(LocalDate.class, new LocalDateDeserializer(FORMAT_YMD));
        deserializers.put(LocalTime.class, new LocalTimeDeserializer(FORMAT_TIME));
        return builder -> builder.serializersByType(serializers).deserializersByType(deserializers);
    }
}

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    1.3.2 注意点

    1. 枚举方面

    • 如果序列化成对象枚举，需要加注解
      @JsonFormat(shape = JsonFormat.Shape.OBJECT)
      或者
      @JsonSerialize(using = MyEnumSerializer.class)
      在这里插入图片描述

    2. LocalDateTime LocalDate 的序列化和反序列化处理

    • 直接截图，上面代码有，如下：
      在这里插入图片描述
      在这里插入图片描述

    1.3.3 单个序列化怎么处理 LocalDateTime？

    • 参考下面的一篇文章，可以解决
      Jackson在springboot中LocalDateTime格式问题
    • 代码如下：
      ObjectMapper objectMapper = new ObjectMapper();

        objectMapper.setDateFormat(new SimpleDateFormat(FORMAT));
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        objectMapper.registerModule(javaTimeModule);

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    2.

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  • 原文地址：https://blog.csdn.net/suixinfeixiangfei/article/details/126319346