工欲善其事

由于项目中使用Spring Boot 2.0，以及需要将包含LocalDateTime的对象通过注解@Cacheable存入缓存。若不做配置，存入缓存会成功（redis数据类型为HEX，不便阅读），取出对象时则会报错反序列化失败。下面是具体解决办法：

需要增加一个修改RedisCacheManager序列化格式的RedisConfig类，包含LocalDateTime类型属性不需要添加任何注解。

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.cache.RedisCacheWriter;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.StringRedisSerializer;
 
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
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;
 
@Configuration
public class RedisConfig {
    /** 默认日期时间格式 */
    private static final String    DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
    /** 默认日期格式 */
    private static final String    DEFAULT_DATE_FORMAT      = "yyyy-MM-dd";
    /** 默认时间格式 */
    private static final String    DEFAULT_TIME_FORMAT      = "HH:mm:ss";
 
    @Autowired
    private RedisConnectionFactory redisConnectionFactory;
 
    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        Jackson2JsonRedisSerializer<Object> serializer = new Jackson2JsonRedisSerializer<Object>(
            Object.class);
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
 
        //LocalDateTime系列序列化和反序列化模块，继承自jsr310，我们在这里修改了日期格式
        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);
 
        serializer.setObjectMapper(objectMapper);
 
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(serializer);
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(serializer);
        redisTemplate.afterPropertiesSet();
 
        return redisTemplate;
    }
 
    @Bean
    public RedisCacheManager redisCacheManager(RedisTemplate<String, Object> redisTemplate) {
        RedisCacheWriter redisCacheWriter = RedisCacheWriter
            .nonLockingRedisCacheWriter(redisTemplate.getConnectionFactory());
        RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration
            .defaultCacheConfig().serializeValuesWith(
                RedisSerializationContext.SerializationPair.fromSerializer(redisTemplate
                    .getValueSerializer()));
        return new RedisCacheManager(redisCacheWriter, redisCacheConfiguration);
    }
}

至此，存取缓存均无问题，且redis数据类型为Plain Text。

另外，附加一个Controller对外统一格式化时间类型的配置，通过这样的配置可以实现，所有进出Controller的时间格式均按照默认格式处理，不需要单独在LocalDateTime属性上增加格式化注解。

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.*;
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.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.convert.converter.Converter;
 
import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.Date;
 
@Configuration
public class DateConfig {
 
    /** 默认日期时间格式 */
    public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
    /** 默认日期格式 */
    public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    /** 默认时间格式 */
    public static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";
 
    /**
     * LocalDate转换器，用于转换RequestParam和PathVariable参数
     */
    @Bean
    public Converter<String, LocalDate> localDateConverter() {
        return new Converter<String, LocalDate>() {
            @Override
            public LocalDate convert(String source) {
                return LocalDate.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT));
            }
        };
    }
 
    /**
     * LocalDateTime转换器，用于转换RequestParam和PathVariable参数
     */
    @Bean
    public Converter<String, LocalDateTime> localDateTimeConverter() {
        return new Converter<String, LocalDateTime>() {
            @Override
            public LocalDateTime convert(String source) {
                return LocalDateTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT));
            }
        };
    }
 
    /**
     * LocalTime转换器，用于转换RequestParam和PathVariable参数
     */
    @Bean
    public Converter<String, LocalTime> localTimeConverter() {
        return new Converter<String, LocalTime>() {
            @Override
            public LocalTime convert(String source) {
                return LocalTime.parse(source, DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT));
            }
        };
    }
 
    /**
     * Date转换器，用于转换RequestParam和PathVariable参数
     */
    @Bean
    public Converter<String, Date> dateConverter() {
        return new Converter<String, Date>() {
            @Override
            public Date convert(String source) {
                SimpleDateFormat format = new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);
                try {
                    return format.parse(source);
                } catch (ParseException e) {
                    throw new RuntimeException(e);
                }
            }
        };
    }
 
 
    /**
     * Json序列化和反序列化转换器，用于转换Post请求体中的json以及将我们的对象序列化为返回响应的json
     */
    @Bean
    public ObjectMapper objectMapper(){
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        objectMapper.disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);
 
        //LocalDateTime系列序列化和反序列化模块，继承自jsr310，我们在这里修改了日期格式
        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)));
 
 
        //Date序列化和反序列化
        javaTimeModule.addSerializer(Date.class, new JsonSerializer<Date>() {
            @Override
            public void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
                SimpleDateFormat formatter = new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);
                String formattedDate = formatter.format(date);
                jsonGenerator.writeString(formattedDate);
            }
        });
        javaTimeModule.addDeserializer(Date.class, new JsonDeserializer<Date>() {
            @Override
            public Date deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException {
                SimpleDateFormat format = new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);
                String date = jsonParser.getText();
                try {
                    return format.parse(date);
                } catch (ParseException e) {
                    throw new RuntimeException(e);
                }
            }
        });
 
        objectMapper.registerModule(javaTimeModule);
        return objectMapper;
    }
}