Spring 序列化与反序列化

Spring 默认使用 Jackson 库来序列化和反序列化 JSON 数据。Jackson 是一个流行的 JSON 处理库，功能强大且易于使用，Spring 项目会自动配置 Jackson 来处理 JSON 数据的转换。

序列化配置

全局配置

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class JacksonConfig {

    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        // 例如，启用pretty-printing
        mapper.enable(SerializationFeature.INDENT_OUTPUT);
        // 其他配置...
        return mapper;
    }
}

自定义

序列化器

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import java.io.IOException;

public class CustomSerializer extends JsonSerializer<MyClass> {

    @Override
    public void serialize(MyClass value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
        gen.writeStartObject();
        gen.writeStringField("customField", value.getCustomField());
        // 其他字段...
        gen.writeEndObject();
    }
}

反序列化器

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import java.io.IOException;

public class CustomDeserializer extends JsonDeserializer<MyClass> {

    @Override
    public MyClass deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
        // 自定义反序列化逻辑
        return new MyClass();
    }
}

注册

import com.fasterxml.jackson.databind.module.SimpleModule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class JacksonConfig {

    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addSerializer(MyClass.class, new CustomSerializer());
        module.addDeserializer(MyClass.class, new CustomDeserializer());
        mapper.registerModule(module);
        return mapper;
    }
}

或者，使用@JsonSerialize，@JsonDeserialize来序列化或反序列化

import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;

@JsonSerialize(using = CustomSerializer.class)
@JsonDeserialize(using = CustomDeserializer.class)
public class MyClass {
    // do something
}

序列化日期

方式一：全局配置日期格式

spring:
  jackson:
    date-format: yyyy-MM-dd HH:mm:ss

方式二：使用@JsonFormat注解

@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
private Date effectTime;

方式三：自定义 ObjectMapper 配置

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.text.SimpleDateFormat;

@Configuration
public class JacksonConfig {

    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.registerModule(new JavaTimeModule());
        objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        return objectMapper;
    }
}

方式四：使用自定义的日期转换器

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;

import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class CustomDateDeserializer extends JsonDeserializer<Date> {

    private static final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    @Override
    public Date deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
        String date = p.getText();
        try {
            return dateFormat.parse(date);
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
    }
}

使用

@JsonDeserialize(using = CustomDateDeserializer.class)
private Date effectTime;