How to map column with type bit(24) in postgresql with hibernate?
1 answer
by
darrion.kuhn ,
8 months ago
@orpha
In PostgreSQL, the bit(24) data type is used to store a fixed-length bit string of 24 bits. To map this column type with Hibernate, you can use the @Type annotation along with a custom BitStringType class that implements the org.hibernate.usertype.UserType interface.
First, create a custom BitStringType class that converts the 24-bit String to a byte array and vice versa:
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import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.usertype.UserType;
import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
public class BitStringType implements UserType {
@Override
public int[] sqlTypes() {
return new int[]{Types.VARBINARY};
}
@Override
public Class returnedClass() {
return String.class;
}
@Override
public boolean equals(Object x, Object y) throws HibernateException {
return x.equals(y);
}
@Override
public int hashCode(Object x) throws HibernateException {
return x.hashCode();
}
@Override
public Object nullSafeGet(ResultSet rs, String[] names, SharedSessionContractImplementor session, Object owner) throws HibernateException, SQLException {
byte[] bytes = rs.getBytes(names[0]);
if (bytes == null) {
return null;
}
return bytes.toString();
}
@Override
public void nullSafeSet(PreparedStatement st, Object value, int index, SharedSessionContractImplementor session) throws HibernateException, SQLException {
if (value == null) {
st.setNull(index, Types.VARBINARY);
} else {
byte[] bytes = ((String) value).getBytes();
st.setBytes(index, bytes);
}
}
@Override
public Object deepCopy(Object value) throws HibernateException {
return value;
}
@Override
public boolean isMutable() {
return false;
}
@Override
public Serializable disassemble(Object value) throws HibernateException {
return (Serializable) value;
}
@Override
public Object assemble(Serializable cached, Object owner) throws HibernateException {
return cached;
}
@Override
public Object replace(Object original, Object target, Object owner) throws HibernateException {
return original;
}
}
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Next, annotate the column in your entity class with @Type and specify the BitStringType class:
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import org.hibernate.annotations.Type;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class YourEntity {
@Id
@GeneratedValue
private long id;
@Column
@Type(type = "com.example.BitStringType")
private String yourBitStringColumn;
// getters/setters
}
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With this setup, Hibernate will use the custom BitStringType class to map the bit(24) column in PostgreSQL to a Java String in your entity class.