Question

遵循此https://docs.datastax.com/en/developer/java-driver/3.2/manual/object_mapper/custom_codecs/和this 我为这个类编写了自己的自定义编解码器，这是我的键空间中的用户类型

public class Condition{
 BigDecimal value;
 LocalDate validFrom;
 LocalDate validUntil;
 Set<Integer> ids;
}

如果我手动注册它，它会工作，但我想像示例中那样注释列：

 @Column(codec = MyCustomDateCodec.class)
 private MyCustomDate birth;

只有在我的自定义编解码器实现中有一个no-args构造函数时，这才有效。

问题是我不知道怎么写没有args构造函数。

我的自定义编解码器：

import com.datastax.driver.core.ProtocolVersion;
import com.datastax.driver.core.TypeCodec;
import com.datastax.driver.core.UDTValue;
import com.datastax.driver.core.UserType;
import com.datastax.driver.core.exceptions.InvalidTypeException;
import com.datastax.driver.extras.codecs.jdk8.LocalDateCodec;

import java.nio.ByteBuffer;

public class ConditionCodec extends TypeCodec<Condition> {

  private TypeCodec<UDTValue> innerCodec;

  private  UserType userType;

  public ConditionCodec(TypeCodec<UDTValue> innerCodec, Class<Condition> javaType) {
    super(innerCodec.getCqlType(), javaType);
    this.innerCodec = innerCodec;
    this.userType = (UserType) innerCodec.getCqlType();
  }


  @Override
  public ByteBuffer serialize(Condition condition, ProtocolVersion protocolVersion) throws InvalidTypeException {
    return innerCodec.serialize(toUDTValue(condition), protocolVersion);
  }

  @Override
  public Condition deserialize(ByteBuffer byteBuffer, ProtocolVersion protocolVersion) throws InvalidTypeException {
    return toCondition(innerCodec.deserialize(byteBuffer, protocolVersion));
  }

  @Override
  public Condition parse(String value) throws InvalidTypeException {
    return value == null || value.isEmpty() || value.equals(null) ? null : toCondition(innerCodec.parse(value));
  }

  @Override
  public String format(Condition value) throws InvalidTypeException {
    return value == null ? null : innerCodec.format(toUDTValue(value));

  }

  protected Condition toCondition(UDTValue value) {
    return value == null ? null
        : new Condition(value.getDecimal("value"), value.get("validFrom", LocalDateCodec.instance),
            value.get("validUntil", LocalDateCodec.instance), value.getSet("storeIds", Integer.class));
  }

  protected UDTValue toUDTValue(Condition value) {

    return value == null ? null
        : userType.newValue().setDecimal("value", value.getValue())
            .set("validFrom", value.getValidFrom(), LocalDateCodec.instance)
            .set("validUntil", value.getValidFrom(), LocalDateCodec.instance).setSet("storeIds", value.getStoreIds());
  }

}

没有自定义Cassandra Codec java的Args构造函数

0 个答案: