Posted on 2011-05-06 13:42
Kavin 阅读(2127)
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Hibernate ID generator 自定义主键生成器
/**
*
*/
package com.ge.hc.eapp.generator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.HibernateException;
import org.hibernate.MappingException;
import org.hibernate.dialect.Dialect;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.id.Configurable;
import org.hibernate.id.IdentifierGenerator;
import org.hibernate.id.PersistentIdentifierGenerator;
import org.hibernate.type.Type;
import java.io.Serializable;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Properties;
/**
* @author Kavin
*
*/
public class DispNoGenerator implements IdentifierGenerator, Configurable {
private static final Log log = LogFactory.getLog(DispNoGenerator.class);
//存储最大值的数组的容量
private static final int MAX_CAPACITY = 2000;
/* 同步锁 */
private static final Object lock = new Object();
//存储表存储在数组中的索引值
private static Map map = new HashMap();
//最大值数组
private static long[] seqs = new long[MAX_CAPACITY];
//最大值数组已经使用的容量
private static int lastIndex;
//递增步长，默认加1
private int step = 1;
private String key;
private String sql;
private Connection connection;
private Class returnClass;
public Serializable generate(SessionImplementor session, Object object)
throws HibernateException {
// TODO Auto-generated method stub
connection = session.connection();
// long seq = -1;
//找到索引值
// int index = findIndex();
// //把最大值加1
// seqs[index] = seqs[index] + step;
//
// seq = seqs[index];
String strGenerateId = null;
System.out.println("this.sql="+this.sql);
try {
long t_SeqNo = this.getSeqValue();
System.out.println("t_SeqNo="+t_SeqNo);
//得到流水号,是自己写的工具类生成的.形式为000x
String seqStr = String.valueOf(t_SeqNo);
//JspFormate.currentFormateORM(seq);
//得到yymmdd,是自己写的方法工具类生成的yymmdd
String preDate = "20110506";
//得到hhmmss,是自己写的工具类获取的hhmmss
//String preHour = JspFormate.dateFormateOnlyHHMMSSORM(new Date());
String preHour = "1035";
strGenerateId = preDate + preHour + seqStr;
} catch (SQLException e) {
log.error(e);
e.printStackTrace();
}
return strGenerateId;
}
/**
* 找到表中自动增长字段存储在数组中的索引值
* @return 索引值
*/
private int findIndex() {
int index = 0;
//首先中缓存中取出索引值
Integer integer = (Integer) map.get(key);
//如果没有找到就从数据库中读出最大值并进行cache
if (null == integer) {
//double check lock
synchronized (lock) {
integer = (Integer) map.get(key);
if (null == integer) {
long maxvalue = 1;
try {
maxvalue = this.getSeqValue();
} catch (SQLException e) {
log.error(e);
}
maxvalue = new Long(0).longValue();
integer = new Integer(lastIndex++);
seqs[integer.intValue()] = maxvalue;
map.put(key, integer);
}
}
}
index = integer.intValue();
return index;
}
public void configure(Type type, Properties params, Dialect d)
throws MappingException {
// 取出table参数
String table = params.getProperty("table");
if (table == null) {
table = params.getProperty(PersistentIdentifierGenerator.TABLE);
}
//取出column参数
String column = params.getProperty("column");
if (column == null) {
column = params.getProperty(PersistentIdentifierGenerator.PK);
}
//表的sehcma参数
String schema = params.getProperty(PersistentIdentifierGenerator.SCHEMA);
returnClass = type.getReturnedClass();
//取出step参数
String stepvalue = params.getProperty("step");
if ((null != stepvalue) && !"".equals(stepvalue.trim())) {
try {
step = Integer.parseInt(stepvalue);
} catch (Exception e) {
log.error(e);
}
}
//构造存储在Map中的索引值的key name
key = table + "_$_" + column;
//根据参数构造取最大值的SQL
sql = "select SEQ_COMPANY_ID.nextval from dual";
}
/**
* 取指定SEQUENCE的值，不存在记录返回0
* @return Sequence最大值
* @throws SQLException if sql error occurs.
*/
private long getSeqValue() throws SQLException {
long maxvalue = 0;
PreparedStatement st = connection.prepareStatement(sql);
System.out.println("============================================" + sql);
ResultSet rs = null;
try {
rs = st.executeQuery();
if (rs.next()) {
maxvalue = rs.getLong(1);
}
sql = null;
} finally {
if (rs != null) {
rs.close();
}
st.close();
}
return maxvalue;
}
/**
* 取指定表中id字段的最大值，不存在记录返回0
* @return 最大值
* @throws SQLException if sql error occurs.
*/
private long getMaxvalue() throws SQLException {
long maxvalue = 0;
PreparedStatement st = connection.prepareStatement(sql);
System.out.println("============================================" + sql);
ResultSet rs = null;
try {
rs = st.executeQuery();
if (rs.next()) {
maxvalue = rs.getLong(1);
}
sql = null;
} finally {
if (rs != null) {
rs.close();
}
st.close();
}
return maxvalue;
}
}
Hibernate 配置文件
<id name="userId" type="java.lang.String">
<column name="USER_ID" />
<generator class="com.xx.generator.DispNoGenerator" />
</id>