如何使用blob数据类型在cassandra中存储对象 [英] How can I store Objects in cassandra using the blob datatype
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问题描述
我尝试使用数据类型 blob
。这是一些Datastax异常。我试过对象本身,bytearray。仍然没有好:
原因:com.datastax.driver.core.exceptions.InvalidQueryException:STRING常量无效([B @ 547248ad)b类型的user_object
这是失败的INSERT:
executeSting.append(INSERT INTO htadb.objecttable(object_id,bucket_name,object_key,link,user_status,user_object))
.append(VALUES ()
.append(objectId).append(,')
.append(bucketName).append(',')
.append ',')
.append(link).append(',')
.append(online)。append(',')
.append (serializer(register))。append(')
+;);
解决方案
来自文档
blob | blob |任意字节(无验证),以十六进制表示
所以你需要的是字节类。以下是我用来序列化/反序列化Java对象的接口我需要保存在Cassandra中
public interface Bufferable extends Serializable {
static final Logger LOGGER = LoggerFactory.getLogger(Bufferable.class);
默认ByteBuffer serialize(){
try(ByteArrayOutputStream bytes = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bytes);){
oos.writeObject (这个);
String hexString = Bytes.toHexString(bytes.toByteArray());
return Bytes.fromHexString(hexString);
} catch(IOException e){
LOGGER.error(Serializing bufferable object error,e);
return null;
}
}
public static Bufferable deserialize(ByteBuffer bytes){
String hx = Bytes.toHexString(bytes);
ByteBuffer ex = Bytes.fromHexString(hx);
try(ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(ex.array()));){
return(Bufferable)ois.readObject
} catch(ClassNotFoundException | IOException e){
LOGGER.error(反序列化可缓冲对象错误,e);
return null;
}
}
}
HTH,
Carlo
I tried with the data type blob
. That's giving some Datastax exception. I tried the object itself, bytearray. Still no good:
Caused by: com.datastax.driver.core.exceptions.InvalidQueryException: Invalid STRING constant ([B@547248ad) for user_object of type blob
This is the failing INSERT:
executeSting.append("INSERT INTO htadb.objecttable (object_id, bucket_name, object_key, link, user_status, user_object) ")
.append("VALUES (")
.append(objectId).append(",'")
.append(bucketName).append("','")
.append(key).append("','")
.append(link).append("','")
.append("online").append("','")
.append(serializer(register)).append("')"
+ ";");
解决方案
From documentation
blob | blobs | Arbitrary bytes (no validation), expressed as hexadecimal
so what you need is provided by the Bytes class. The following is an interface I use to serialize/deserialize Java objects I need to save in Cassandra
public interface Bufferable extends Serializable {
static final Logger LOGGER = LoggerFactory.getLogger(Bufferable.class);
default ByteBuffer serialize() {
try (ByteArrayOutputStream bytes = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bytes);) {
oos.writeObject(this);
String hexString = Bytes.toHexString(bytes.toByteArray());
return Bytes.fromHexString(hexString);
} catch (IOException e) {
LOGGER.error("Serializing bufferable object error", e);
return null;
}
}
public static Bufferable deserialize(ByteBuffer bytes) {
String hx = Bytes.toHexString(bytes);
ByteBuffer ex = Bytes.fromHexString(hx);
try (ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(ex.array()));) {
return (Bufferable) ois.readObject();
} catch (ClassNotFoundException | IOException e) {
LOGGER.error("Deserializing bufferable object error", e);
return null;
}
}
}
HTH, Carlo
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