Spring Redis（6）Redis持久化

﹏ヽ暗。殇╰゛Y 2022-06-17 00:19 204阅读 0赞

# Redis持久化 #

RedisRepositories能够简化将实体存入Hash的操作，并自动维护索引字段。只需要象Hibernate那样使用save、delete等简单方法即可持久化数据到Redis。

> Redis Repositories最低需要Redis 2.8.0.

### 简单使用 ###

定义实体

// 定义Redis实体的keyspace为persons
    @RedisHash("persons")
    public class Person { 
    
      // 每个Redis实体必须有且只有一个@Id
      @Id 
      String id;
      String firstname;
      String lastname;
      Address address;
    }
    
    public class Address { 
      String city;
      String country;
    }

定义Repository 接口，CrudRepository 提供基本的CRUD和查找方法，Spring将自动生成该接口的实现类

public interface PersonRepository extends CrudRepository<Person, String> { }

定义配置类，默认扫描配置类所在包下的类，可以通过注解EnableRedisRepositories的参数来指定扫描的包，如@EnableRedisRepositories(\{“com.htfg.\*”\})

@Configuration
    @EnableRedisRepositories
    public class ApplicationConfig { 
    
      @Bean
      public RedisConnectionFactory connectionFactory() {
        return new JedisConnectionFactory();
      }
    
      @Bean
      public RedisTemplate<?, ?> redisTemplate() {
    
        RedisTemplate<byte[], byte[]> template = new RedisTemplate<byte[], byte[]>();
        return template;
      }
    }

@Autowired PersonRepository repo; public void basicCrudOperations() { Person rand = new Person("rand", "al'thor"); rand.setAddress(new Address("emond's field", "andor")); // 如果rand的id值不存在，将会自动创建 // 默认生成hash的key为keyspace:id样式，例如persons:5d67b7e1-8640-4475-beeb-c666fab4c0e5 repo.save(rand); // 使用keyspace:id查找数据 repo.findOne(rand.getId()); repo.count(); repo.delete(rand); }

### 对象映射到Hash ###

上文的Peron对象将被用以下方式存储到Redis的hash中  
key值等于”persons:5d67b7e1-8640-4475-beeb-c666fab4c0e5”  
field、value包括

_class = org.example.Person           
    id = 5d67b7e1-8640-4475-beeb-c666fab4c0e5
    firstname = rand                       
    lastname = al’thor
    address.city = emond's field          
    address.country = andor

> \_class属性为Redis实体的类名
> 
> 复杂的类型属性用点号分隔路径

##### Java映射规则 #####

###### 简单类型，如String ######

String firstname = “rand”;

映射为

firstname = “rand”

###### 复合类型，如Address对象 ######

Address adress = new Address(“emond’s field”);

映射为

address.city = “emond’s field”

###### List ######

List nicknames = asList(“dragon reborn”, “lews therin”);

映射为

nicknames.\[0\] = “dragon reborn”,  
nicknames.\[1\] = “lews therin”

###### Map ######

Map

###### List复合类型 ######

List

addresses = asList(new Address(“em…

映射为

addresses.\[0\].city = “emond’s field”,  
addresses.\[1\].city = “…

###### Map复合类型 ######

Map

##### 自定义映射规则 #####

###### Json映射 ######

@WritingConverter public class AddressToBytesConverter implements Converter<Address, byte[]> { private final Jackson2JsonRedisSerializer<Address> serializer; public AddressToBytesConverter() { serializer = new Jackson2JsonRedisSerializer<Address>(Address.class); serializer.setObjectMapper(new ObjectMapper()); } @Override public byte[] convert(Address value) { return serializer.serialize(value); } } @ReadingConverter public class BytesToAddressConverter implements Converter<byte[], Address> { private final Jackson2JsonRedisSerializer<Address> serializer; public BytesToAddressConverter() { serializer = new Jackson2JsonRedisSerializer<Address>(Address.class); serializer.setObjectMapper(new ObjectMapper()); } @Override public Address convert(byte[] value) { return serializer.deserialize(value); } }

使用上面的定制Converter将生成下面的类似的filed和value

_class = org.example.Person
    id = e2c7dcee-b8cd-4424-883e-736ce564363e
    firstname = rand
    lastname = al’thor
    address = { city : "emond's field", country : "andor" }

###### 自定义映射 ######

@WritingConverter public class AddressToMapConverter implements Converter<Address, Map<String,byte[]>> { @Override public Map<String,byte[]> convert(Address source) { return singletonMap("ciudad", source.getCity().getBytes()); } } @ReadingConverter public class MapToAddressConverter implements Converter<Address, Map<String, byte[]>> { @Override public Address convert(Map<String,byte[]> source) { return new Address(new String(source.get("ciudad"))); } }

使用上面的定制Converter将生成下面的类似的filed和value

_class = org.example.Person id = e2c7dcee-b8cd-4424-883e-736ce564363e firstname = rand lastname = al’thor ciudad = "emond's field"

### Keyspaces ###

Keyspaces定义前缀用于创建Hash的key，默认使用在Redis实体的getClass().getName(）。

可通过在Redis实体注解RedisHash 参数设置

@RedisHash("persons")
    public class Person {
    
    }

也可以在配置类中用EnableRedisRepositories设置。

@Configuration @EnableRedisRepositories(keyspaceConfiguration = MyKeyspaceConfiguration.class) public class ApplicationConfig { //... RedisConnectionFactory and RedisTemplate Bean definitions omitted public static class MyKeyspaceConfiguration extends KeyspaceConfiguration { @Override protected Iterable<KeyspaceSettings> initialConfiguration() { return Collections.singleton(new KeyspaceSettings(Person.class, "persons")); } } }

或者在配置类中编码设置

@Configuration @EnableRedisRepositories public class ApplicationConfig { //... RedisConnectionFactory and RedisTemplate Bean definitions omitted @Bean public RedisMappingContext keyValueMappingContext() { return new RedisMappingContext( new MappingConfiguration( new MyKeyspaceConfiguration(), new IndexConfiguration())); } public static class MyKeyspaceConfiguration extends KeyspaceConfiguration { @Override protected Iterable<KeyspaceSettings> initialConfiguration() { return Collections.singleton(new KeyspaceSettings(Person.class, "persons")); } } }

### 索引 ###

Redis对字段的索引是通过

### TTL ###