今天遇到一个问题是：
在mysql手动创建数据库表（大写表名，小写字段名）后，启动项目后发现，hibernate又给我生成了一个小写的同结构表，猜想到会不会是mysql表名区分大小写后，google一下，果不其然，LINUX下的MYSQL默认是要区分表名大小写的；据说有个规则是：
MYSQL在LINUX下数据库名、表名、列名、别名大小写规则如下：
1.数据库名与表名是严格区分大小写的
2.表的别名是严格区分大小写的
3.列名与列的别名在所有的情况下均是忽略大小写的
4.变量名也是严格区分大小写的
看到这基本确认是mysql表名大小写问题，但是突然想到该项目之前在使用oracle数据库生成的表名都是大写，再次google，原来oracle在建表时候，大小写都是可以的（默认大写，小写的话，加引号），而且查询的时候不区分大小写，所以不会出现上面mysql的问题，查询的大小写表是两个表。
可是，我这项目都生成了30多个表，不能让我挨个修改小写吧，想到这里，记起曾经看过hibernate的一个关于从class--》table等命名映射规则类，再次google，查到：原来是只要：“扩展org.hibernate.cfg.ImprovedNamingStrategy 命名策略，然后在配置文件中指向自己的命名配置文件即可”，ok，明白了，开始复写一个ImprovedNamingStrategy，将里面的方法tableName修改为
public String tableName(String tableName) {
return addUnderscores(tableName).toUpperCase();
}
最后我的ImprovedNamingStrategy就是：
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Middleware LLC.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*
*/
package com.qiyi.act.utils;
import java.io.Serializable;
import org.hibernate.cfg.NamingStrategy;
import org.hibernate.util.StringHelper;
import org.hibernate.AssertionFailure;
/**
* An improved naming strategy that prefers embedded
* underscores to mixed case names
* @see org.hibernate.cfg.DefaultNamingStrategy the default strategy
* @author Gavin King
*/
public class ImprovedNamingStrategy implements NamingStrategy, Serializable {
/**
* A convenient singleton instance
*/
public static final NamingStrategy INSTANCE = new ImprovedNamingStrategy();
/**
* Return the unqualified class name, mixed case converted to
* underscores
*/
public String classToTableName(String className) {
return addUnderscores( StringHelper.unqualify(className) );
}
/**
* Return the full property path with underscore seperators, mixed
* case converted to underscores
*/
public String propertyToColumnName(String propertyName) {
return addUnderscores( StringHelper.unqualify(propertyName) );
}
/**
* Convert mixed case to underscores
*/
public String tableName(String tableName) {
return addUnderscores(tableName).toUpperCase();
}
/**
* Convert mixed case to underscores
*/
public String columnName(String columnName) {
return addUnderscores(columnName);
}
protected static String addUnderscores(String name) {
StringBuffer buf = new StringBuffer( name.replace('.', '_') );
for (int i=1; i<buf.length()-1; i++) {
if (
Character.isLowerCase( buf.charAt(i-1) ) &&
Character.isUpperCase( buf.charAt(i) ) &&
Character.isLowerCase( buf.charAt(i+1) )
) {
buf.insert(i++, '_');
}
}
return buf.toString().toLowerCase();
}
public String collectionTableName(
String ownerEntity, String ownerEntityTable, String associatedEntity, String associatedEntityTable,
String propertyName
) {
return tableName( ownerEntityTable + '_' + propertyToColumnName(propertyName) );
}
/**
* Return the argument
*/
public String joinKeyColumnName(String joinedColumn, String joinedTable) {
return columnName( joinedColumn );
}
/**
* Return the property name or propertyTableName
*/
public String foreignKeyColumnName(
String propertyName, String propertyEntityName, String propertyTableName, String referencedColumnName
) {
String header = propertyName != null ? StringHelper.unqualify( propertyName ) : propertyTableName;
if (header == null) throw new AssertionFailure("NamingStrategy not properly filled");
return columnName( header ); //+ "_" + referencedColumnName not used for backward compatibility
}
/**
* Return the column name or the unqualified property name
*/
public String logicalColumnName(String columnName, String propertyName) {
return StringHelper.isNotEmpty( columnName ) ? columnName : StringHelper.unqualify( propertyName );
}
/**
* Returns either the table name if explicit or
* if there is an associated table, the concatenation of owner entity table and associated table
* otherwise the concatenation of owner entity table and the unqualified property name
*/
public String logicalCollectionTableName(String tableName,
String ownerEntityTable, String associatedEntityTable, String propertyName
) {
if ( tableName != null ) {
return tableName;
}
else {
//use of a stringbuffer to workaround a JDK bug
return new StringBuffer(ownerEntityTable).append("_")
.append(
associatedEntityTable != null ?
associatedEntityTable :
StringHelper.unqualify( propertyName )
).toString();
}
}
/**
* Return the column name if explicit or the concatenation of the property name and the referenced column
*/
public String logicalCollectionColumnName(String columnName, String propertyName, String referencedColumn) {
return StringHelper.isNotEmpty( columnName ) ?
columnName :
StringHelper.unqualify( propertyName ) + "_" + referencedColumn;
}
}最后，在spring配置文件的sessionFactory属性中加入：
<property name="namingStrategy">
<bean class="com.wayne.utils.ImprovedNamingStrategy"/>
</property>
参考资料：
http://blog.csdn.net/wocjj/article/details/7415200
http://bbs.csdn.net/topics/10356601
http://s.yanghao.org/program/viewdetail.php?i=120816
来源：oschina
链接：https://my.oschina.net/u/699245/blog/110297