技術標籤：Springmongodbspringjavaspring bootmongodb

MongoDB+SpringBoot 自定義型別轉換器

直接程式碼

package pers.jssd.mongodbcostomconverter.config;

import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.core.convert.converter.Converter;
 

import org.springframework.data.convert.ReadingConverter;
import org.springframework.data.convert.WritingConverter;
import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
import pers.jssd.mongodbcostomconverter.entity.constant.SexEnum;

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

/**
 * MongoDB 自定義轉換器
 *
 * @author [email protected]
 * @date 2021/1/16 16:02
 */
@SpringBootConfiguration
public class MongoConverterConfig {

    /**
     * 註冊 自定義的mongo轉換器
     *
     * @return 返回註冊成功的 MongoCustomConversions 
     */
    @Bean
    public MongoCustomConversions customConversions
 
() {
        return MongoCustomConversions.create(mongoConverterConfigurationAdapter -> {
            mongoConverterConfigurationAdapter.registerConverter(new CustomLocalDateTimeToStringConverter());
            mongoConverterConfigurationAdapter.registerConverter(new CustomStringToLocalDateTimeConverter());
            mongoConverterConfigurationAdapter.registerConverter(new CustomEnumToIntegerConverter());
            mongoConverterConfigurationAdapter.registerConverter(new CustomIntegerToEnumConverter());

        });
    }

    @WritingConverter
    private static class CustomLocalDateTimeToStringConverter implements Converter<LocalDateTime, String> {

        @Override
        public String convert(LocalDateTime source) {
            DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            return df.format(source);
        }
    }

    @ReadingConverter
    private static class CustomStringToLocalDateTimeConverter implements Converter<String, LocalDateTime> {

        @Override
        public LocalDateTime convert(String source) {
            DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            try {
                return LocalDateTime.parse(source, df);
            } catch (Exception e) {
                return null;
            }
        }
    }

    @WritingConverter
    private static class CustomEnumToIntegerConverter implements Converter<SexEnum, Integer> {
        @Override
        public Integer convert(SexEnum source) {
            return source.ordinal();
        }
    }

    @ReadingConverter
    private static class CustomIntegerToEnumConverter implements Converter<Integer, SexEnum> {
        @Override
        public SexEnum convert(Integer source) {
            if (source < 0 || source >= SexEnum.values().length) {
                throw new IndexOutOfBoundsException("Invalid ordinal");
            }
            return SexEnum.values()[source];
        }
    }

}

這裡定義了四個轉換器, 一個是 LocalDateTime 和 String 互轉, 一個是 列舉型別和 Integer互轉.

注意 @WritingConverter 和 @ReadingConverter 註解. 這兩個註解的意思是, 往庫中寫東西時候執行, 和從庫中讀取資料時候執行. 不能省略的, 比如我把列舉轉換的ReadingConverter去掉了, 存庫的時候, 所有的Integer型別欄位都會嘗試轉換為Enum, 轉換失敗就報錯.