jaskon序列化记录

jackson序列化(自定义序列化)

前言: 为什么要做写这个记录。是因为遇到前端js读取long类型的值，long类型的值太大。19位数字。比如idworker生成的id就很难处理。直接出现精度丢失的问题。这样就需要传回前端前选择性的把long属性转成string类型的值。废话不错说。直接举例子。

环境： 本例子环境是 在springboot2.0搭建的

1.首先导入依赖

  <dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-databindartifactId>
        dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatypegroupId>
            <artifactId>jackson-datatype-jsr310artifactId>
        dependency>


  <dependency>
            <groupId>org.apache.commonsgroupId>
            <artifactId>commons-lang3artifactId>
            <version>3.9version>
        dependency>

2.自定义转换器

目前是只要是long类型就全部转成string ，可以通过key值来筛选来些需要转的属性值。目前注释起来了

package com.comit.systemConfig;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonStreamContext;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;
import org.apache.commons.lang3.StringUtils;

import java.io.IOException;

public class IdSerializer extends StdSerializer<Long> {
    public IdSerializer() {
        this(null);
    }

    public IdSerializer(Class<Long> t) {
        super(t);
    }

    @Override
    public void serialize(Long value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        if (value == null) {
            gen.writeNull();
            return;
        }
        JsonStreamContext context = gen.getOutputContext();
        String key = getKeyName(context);
     /*   if ("id".equals(key) || StringUtils.endsWithAny(key, "Id", "Ids","ids","id")) {
            gen.writeString(value.toString());
            return;
        }else{
            gen.writeNumber(value);
        }*/
        gen.writeString(value.toString());
    }

    private String getKeyName(JsonStreamContext context) {
        String name = null;
        while (context != null && (name = context.getCurrentName()) == null) {
            context = context.getParent();
        }
        return name;
    }
}

方案一:jackConfig

我自己也试了一下这个配置文件 并没有起作用

package com.comit.systemConfig;

import com.comit.systemConfig.IdSerializer;
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.JavaTimeModule;
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.apache.commons.lang3.StringUtils;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.convert.converter.Converter;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

//@Configuration
public class JacksonConfig {
    private static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
    private static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    private static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";

    @Bean
    public Converter<String, LocalDateTime> localDateTimeConverter() {
        return new Converter<String, LocalDateTime>() {
            @Override
            public LocalDateTime convert(String source) {
                if (StringUtils.isEmpty(source)) {
                    return null;
                }
                return LocalDateTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT));
            }
        };
    }

    @Bean
    public Converter<String, LocalDate> localDateConverter() {
        return new Converter<String, LocalDate>() {
            @Override
            public LocalDate convert(String source) {
                if (StringUtils.isEmpty(source)) {
                    return null;
                }
                return LocalDate.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT));
            }
        };
    }

    @Bean
    public Converter<String, LocalTime> localTimeConverter() {
        return new Converter<String, LocalTime>() {
            @Override
            public LocalTime convert(String source) {
                if (StringUtils.isEmpty(source)) {
                    return null;
                }
                return LocalTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT));
            }
        };
    }

    @Bean
    public ObjectMapper objectMapper() {
        return getObjectMapper();
    }

    public static ObjectMapper getObjectMapperWithoutIdModule() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
        javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
        javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
        javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
        javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
        objectMapper.registerModule(javaTimeModule);


        return objectMapper;
    }

    public static ObjectMapper getObjectMapper() {
        ObjectMapper objectMapper = getObjectMapperWithoutIdModule();

        SimpleModule idModule = new SimpleModule("id module");
        idModule.addSerializer(Long.class, new IdSerializer());
        idModule.addSerializer(Long.TYPE, new IdSerializer());
       // idModule.addSerializer(String.class, new PraiseRateSerializer());
        objectMapper.registerModule(idModule);

        return objectMapper;
    }
}

方案二 mvc配置文件里加默认的jackson转换器

如果说jackson不起作用。就如下配置就应该搞定了。

在mvc配置文件里加默认的jackson转换器就应该搞定了。

package com.comit.interceptor;

import com.comit.sm.SM2Encryptor;
import com.comit.systemConfig.IdSerializer;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import com.fasterxml.jackson.databind.module.SimpleModule;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.text.SimpleDateFormat;
import java.util.List;
import java.util.TimeZone;

/**
 * @author thh
 * 添加拦截器
 */
@Configuration
@EnableWebMvc
public class CustomWebMvcConfigurerAdapter implements WebMvcConfigurer {




    @Bean
    public MappingJackson2HttpMessageConverter customJackson2HttpMessageConverter() {
    MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter();
       ObjectMapper objectMapper = new ObjectMapper();
     objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
      //  objectMapper.configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL, true);
     //   objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
      //  objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
       // objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));

        SimpleModule idModule = new SimpleModule("id module");
        idModule.addSerializer(Long.class, new IdSerializer());
        idModule.addSerializer(Long.TYPE, new IdSerializer());
        // idModule.addSerializer(String.class, new PraiseRateSerializer());
        objectMapper.registerModule(idModule);

        jsonConverter.setObjectMapper(objectMapper);
        return jsonConverter;
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(customJackson2HttpMessageConverter());
    }
}

3.解决精度丢失的另一种方法。

在pojo的字段或者属性上添加

这种方法只能对pojo上 。无法解决map类型以及其他类型的。所以看个人选择习惯吧。因为项目是一起开发的。有的人喜欢查map，有的人喜欢查对象。所以还是要看个人习惯的话 还是需要自定义的序列化才能满足。或者查出map后 自己手动把id转成string类型的。

测试:

首先自己弄个ajax来测试 手动下载个jq把

<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Jquery 实现异步一title>
    <script src="js/jquery-3.3.1.js">script>
    <script>

        function fun() {

            $.get("http://localhost:8888/api/expert/expertApply/1",{},function (data) {
                alert(data);
				
            });

        }


    script>
head>
<body>
<input type="button" value="异步交互jquery方式"  onclick="fun()"/>
<input type="text"/>
body>
html>