Java tutorial
package com.thinkbiganalytics.jpa; /*- * #%L * thinkbig-commons-jpa * %% * Copyright (C) 2017 ThinkBig Analytics * %% * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * #L% */ import org.apache.commons.lang3.StringUtils; import org.hibernate.HibernateException; import org.hibernate.engine.spi.SessionImplementor; import org.hibernate.type.StandardBasicTypes; import org.hibernate.usertype.ParameterizedType; 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; import java.util.Properties; /** * annotate your String column with something like this * * @Type(type = "com.thinkbiganalytics.jpa.TruncateStringUserType",parameters = {@Parameter(name = "length",value = "250")}) */ public class TruncateStringUserType implements UserType, ParameterizedType { public static final String NAME = "truncateString"; private Integer maxLength = null; @Override public int[] sqlTypes() { return new int[] { Types.VARCHAR }; } @Override public Class returnedClass() { return String.class; } @Override public boolean equals(Object x, Object y) throws HibernateException { return (x == y) || (x != null && y != null && (x.equals(y))); } @Override public int hashCode(Object o) throws HibernateException { assert (o != null); return o.hashCode(); } @Override public Object nullSafeGet(ResultSet resultSet, String[] names, SessionImplementor sessionImplementor, Object o) throws HibernateException, SQLException { String val = (String) StandardBasicTypes.STRING.nullSafeGet(resultSet, names[0], sessionImplementor, o); return val == null ? null : val.trim(); } @Override public void nullSafeSet(PreparedStatement preparedStatement, Object o, int i, SessionImplementor sessionImplementor) throws HibernateException, SQLException { String val = (String) o; if (val != null) { if (maxLength != null && maxLength > 0 && val.length() > maxLength) { val = val.substring(0, maxLength); } } preparedStatement.setString(i, val); } @Override public Object deepCopy(Object o) throws HibernateException { if (o == null) { return null; } return new String(((String) o)); } @Override public boolean isMutable() { return false; } @Override public Serializable disassemble(Object value) throws HibernateException { return (Serializable) value; } @Override public Object assemble(Serializable cached, Object o) throws HibernateException { return cached; } @Override public Object replace(Object original, Object target, Object owner) throws HibernateException { return original; } @Override public void setParameterValues(Properties parameters) { if (parameters != null && !parameters.isEmpty()) { final String lengthString = parameters.getProperty("length"); try { if (StringUtils.isNotBlank(lengthString)) { this.maxLength = Integer.parseInt(lengthString); } } catch (final NumberFormatException e) { } } } }