AbstractListType.java

package de.flower.rmt.model.db.type;

import org.apache.commons.lang3.StringUtils;
import org.hibernate.HibernateException;
import org.hibernate.type.descriptor.JdbcTypeNameMapper;
import org.hibernate.usertype.UserType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.ArrayList;
import java.util.List;

/**
 * User type to store lists of objects in a single varchar.
 *
 * @param T type of list element
 * @author flowerrrr
 */
public abstract class AbstractListType<T> implements UserType {

    private final static Logger log = LoggerFactory.getLogger(AbstractListType.class);

    private static final int[] SQL_TYPES = new int[]{Types.VARCHAR,};

    @Override
    public int[] sqlTypes() {
        return SQL_TYPES;
    }

    @Override
    public Class returnedClass() {
        return ArrayList.class;
    }

    @Override
    public boolean equals(final Object x, final Object y) throws HibernateException {
        if (x == y) {
            return true;
        }
        if (x == null || y == null) {
            return false;
        }
        List<T> dtx = (List<T>) x;
        List<T> dty = (List<T>) y;

        return dtx.equals(dty);
    }

    @Override
    public int hashCode(final Object x) throws HibernateException {
        return x.hashCode();
    }

    @Override
    public Object nullSafeGet(final ResultSet rs, final String[] names, final Object owner) throws HibernateException, SQLException {
        String serialized = rs.getString(names[0]);
        if (log.isTraceEnabled()) {
            log.trace("found [" + serialized + "] as column [" + names[0] + "]");
        }
        return assemble(serialized, owner);
    }

    @Override
    public void nullSafeSet(final PreparedStatement st, final Object value, final int index) throws HibernateException, SQLException {
        String string = (String) disassemble(value);
        if (log.isTraceEnabled()) {
            log.trace("binding parameter [" + index + "] as [" + JdbcTypeNameMapper.getTypeName(SQL_TYPES[0]) + "] - " + string);
        }
        if (value == null) {
            st.setNull(index, SQL_TYPES[0]);
        } else {
            st.setString(index, string);
        }
    }

    @Override
    public Object deepCopy(final Object value) throws HibernateException {
        return (value == null) ? null : new ArrayList((List) value);
    }

    @Override
    public boolean isMutable() {
        return true;
    }

    @Override
    public Serializable disassemble(final Object value) throws HibernateException {
        return list2String((List<T>) value);
    }

    @Override
    public Object assemble(final Serializable cached, final Object owner) throws HibernateException {
        return string2List((String) cached);
    }

    @Override
    public Object replace(final Object original, final Object target, final Object owner) throws HibernateException {
        return deepCopy(original);
    }

    public String list2String(final List<T> list) {
        if (list == null) {
            return null;
        }
        List<String> strings = new ArrayList<String>();
        for (T object : list) {
            strings.add(toString(object));
        }
        return StringUtils.join(strings, "|");
    }

    public List<T> string2List(final String string) {
        if (string == null) {
            return null;
        }
        String[] strings = StringUtils.split(string, "|");
        List<T> list = new ArrayList();
        for (String s : strings) {
            list.add(fromString(s));
        }
        return list;
    }

    /**
     * Subclasses should override these methods with marshalling/unmarshalling code.
     *
     * @param list
     * @return
     */
    public abstract String toString(T object);

    public abstract T fromString(String string);

    public static class StringListType extends AbstractListType<String> {

        @Override
        public String toString(final String object) {
            return object;
        }

        @Override
        public String fromString(final String string) {
            return string;
        }
    }
}