如何自定义Jackson序列化 @JsonSerialize
目录
- 自定义Jackson序列化 @JsonSerialize
- jackson自定义全局序列化、反序列化
- 创建序列化类
- 创建反序列化类
- 将两个类注册进入jackson核心对象objectMapper
- 小结一下
自定义Jackson序列化 @JsonSerialize
自定义json序列化需要实现StdSerializer<T>或者JsonSerializer<T>。
我要序列化House这个类,加上注解,指定用于序列化的类
package com.xhx.json.entity; import com.fasterxml.jackson.annotation.JsonFormat; import com.fasterxml.jackson.databind.annotation.JsonSerialize; import com.xhx.json.serializers.HourseSerializer; import java.util.Date; @JsonSerialize(using = HourseSerializer.class) public class Hourse { private String location; private Date buildDate; public String getLocation() { return location; } public void setLocation(String location) { this.location = location; } public Date getBuildDate() { return buildDate; } public void setBuildDate(Date buildDate) { this.buildDate = buildDate; } }
package com.xhx.json.serializers; import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.databind.SerializerProvider; import com.fasterxml.jackson.databind.ser.std.StdSerializer; import com.xhx.json.entity.Hourse; import java.io.IOException; public class HourseSerializer extends StdSerializer<Hourse> { public HourseSerializer(){ super(Hourse.class); } protected HourseSerializer(Class<Hourse> t) { super(t); } @Override public void serialize(Hourse hourse, JsonGenerator generator, SerializerProvider provider) throws IOException { generator.writeStartObject(); generator.writeFieldName("id"); generator.writeString("自定义"); generator.writeFieldName("location"); generator.writeString(hourse.getLocation()); generator.writeObjectField("buildDate",hourse.getBuildDate()); generator.writeEndObject(); } }
测试:
jackson自定义全局序列化、反序列化
需要自定义Jackson序列化和反序列化有两种方式,一种是全局定义,一种是非全局定义。先来看看全局定义。全局定义的步骤如下,以定义一个localDateTime的序列化和反序列化为例:
创建序列化类
创建一个序列化类然后继承JsonSerializer,重写serialize序列化方法。其中第一个参数localDateTime为JsonSerializer的泛型,表示的是被序列化的类型的值,第二个参数jsonGenerator表示的是用于输出生成的Json内容,第三个参数暂时没明白什么应用场景。重写方法一般是将想要序列化的字符串传入 jsonGenerator.writeString。
public final class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> { public static final LocalDateTimeSerializer INSTANCE = new LocalDateTimeSerializer(); public LocalDateTimeSerializer() { } @Override public void serialize(LocalDateTime localDateTime, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException { jsonGenerator.writeString(DateUtil.format(localDateTime, DateUtil.DateTimeFormatEnum.DATE_TIME_FORMAT_4)); } }
创建反序列化类
创建两个类,一个类继承JsonDeserializer,一个类继承KeyDeserializer,重写deserialize反序列化方法。参数jsonParser用于读取json内容的解析,deserializationContext可用于访问此有关反序列化的上下文(暂时也不知道怎么用),返回值则是JsonDeserializer的泛型对象,表示要反序列化的对象。一般用法是通过jsonParser.getText().trim()获取该字段json字符串,然后将该字符串转换为对象返回。
public final class LocalTimeDeserializer extends JsonDeserializer<LocalTime> { public static final LocalTimeDeserializer INSTANCE = new LocalTimeDeserializer(); public LocalTimeDeserializer() { } @Override public LocalTime deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException { String text = jsonParser.getText().trim(); return LocalTime.parse(text, DateUtil.DATE_TIME_FORMATTER_6); } } public final class LocalDateTimeKeyDeserializer extends KeyDeserializer { public static final LocalDateTimeKeyDeserializer INSTANCE = new LocalDateTimeKeyDeserializer(); public LocalDateTimeKeyDeserializer() { } @Override public Object deserializeKey(String s, DeserializationContext deserializationContext) throws IOException, JsonProcessingException { return StringUtils.isBlank(s) ? null : LocalDateTime.parse(s, DateUtil.DATE_TIME_FORMATTER_4); } }
将两个类注册进入jackson核心对象objectMapper
@Bean public ObjectMapper objectMapper(){ ObjectMapper objectMapper = new ObjectMapper(); objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY); //不注释,会导致swagger报错 //objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL); //关闭日期序列化为时间戳的功能 objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS); //关闭序列化的时候没有为属性找到getter方法,报错 objectMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS); //关闭反序列化的时候,没有找到属性的setter报错 objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); //序列化的时候序列对象的所有属性 objectMapper.setSerializationInclusion(JsonInclude.Include.ALWAYS); //反序列化的时候如果多了其他属性,不抛出异常 objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false); //如果是空对象的时候,不抛异常 objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false); SimpleModule simpleModule = new SimpleModule(); //json值序列化 simpleModule.addSerializer(LocalDateTime.class, LocalDateTimeSerializer.INSTANCE); //json值反序列化 simpleModule.addDeserializer(LocalDateTime.class, LocalDateTimeDeserializer.INSTANCE); //json键序列化 simpleModule.addKeySerializer(LocalDateTime.class,LocalDateTimeSerializer.INSTANCE); //json键反序列化 simpleModule.addKeyDeserializer(LocalDateTime.class, LocalDateTimeKeyDeserializer.INSTANCE); objectMapper.registerModule(simpleModule); return objectMapper; }
小结一下
以上,通过objectMapper的配置,完成了全局序列化、反序列化的配置,如果不需要全局则通过@jsonserialize或 @JsonDeserialize指定使用的序列化、反序列化类。仅为个人经验,希望能给大家一个参考,也希望大家多多支持我们
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