All help me!

when i restart Tomcat5.0 after a day, it will happen "StackOverflowError"!

if i do not use Threadlocal,mybe it is OK!(do not affirm) why?

I use:

LINUX(REDHAD 8.0)
J2SDK 1.4.2_04
hibernate 2.14 2.13 2.12
tomcat 5.024 5.025 5.026
mysql 4.0
JDBC : mysql driver 3.07 stable


1.HibernateSession

package com.yours.datamodel.hibernate;

import net.sf.hibernate.HibernateException;
import net.sf.hibernate.Session;
import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.Transaction;
import net.sf.hibernate.cfg.Configuration;
import net.sf.hibernate.tool.hbm2ddl.SchemaExport;

import org.apache.log4j.Logger;

/**
*
* 获取Session连接工厂类
*
* @author Robbin Fan
*
*/
public class HibernateSession {

private static final ThreadLocal sessionThread = new ThreadLocal();

private static final ThreadLocal transactionThread = new ThreadLocal();

private static SessionFactory sf = null;

private static Logger log = Logger.getLogger(HibernateSession.class);


/**
* 获取当前线程使用的Session
*
* @return Session
* @throws HibernateException
*/
public static Session currentSession() throws HibernateException {
Session s = (Session) sessionThread.get();
if (s == null) {
if (sf == null) sf = new Configuration().configure().buildSessionFactory();
s = sf.openSession();
sessionThread.set(s);
}
return s;
}

/**
* 获取一个新的Session
*
* @return Session
* @throws HibernateException
*/
public static Session newSession() throws HibernateException {
if (sf == null) sf = new Configuration().configure().buildSessionFactory();
Session s = sf.openSession();
return s;
}

/**
* 启动或者加入当前Session的Transaction
*
* @return Transaction
* @throws HibernateException
*/
public static Transaction currentTransaction() throws HibernateException {
Transaction tx = (Transaction) transactionThread.get();
if (tx == null) {
tx = currentSession().beginTransaction();
transactionThread.set(tx);
}
return tx;
}

/**
* 提交当前Session的Transaction
*
* @throws HibernateException
*/
public static void commitTransaction() throws HibernateException {
Transaction tx = (Transaction) transactionThread.get();
transactionThread.set(null);
if (tx != null) {
tx.commit();
}
}

/**
* 回滚当前事务
*
* @throws HibernateException
*/
public static void rollbackTransaction() throws HibernateException {
Transaction tx = (Transaction) transactionThread.get();
transactionThread.set(null);
if (tx != null) tx.rollback();
}

/**
* 关闭当前线程使用的Session
*
* @throws HibernateException
*/
public static void closeSession() throws HibernateException {
Session s = (Session) sessionThread.get();
sessionThread.set(null);
if (s != null) {
s.close();
}
}

/**
* 根据映射文件和持久对象生成数据库DDL，生成文件为create_table.sql
*
* @param args 参数
*/
public static void main(String[] args) {
try {
String conf = "hibernate.cfg.xml";
if (args.length != 0) conf = args[0];
Configuration cfg = new Configuration().configure("/" + conf);
SchemaExport se = new SchemaExport(cfg);
se.setOutputFile("create_table.sql");
se.create(true,true);
} catch (HibernateException e) {
System.out.println(e.getMessage());
}
}
}


2.SetEncodingFilter


package com.iclass.util;

import com.yours.datamodel.hibernate.HibernateSession;
/**
*
* <p>Description: 解决汉字编码问题</p>
* <p>自动关闭 Hibernate Session</p>
* <p>Copyright: Copyright (c) 2003</p>
* <p>Company: 信息中心</p>
* @author 段洪杰
* @version 1.0
*/

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import net.sf.hibernate.HibernateException;

import org.apache.log4j.Logger;

public class SetEncodingFilter
implements Filter {

private static Logger log = Logger.getLogger(SetEncodingFilter.class);
protected String encoding = null;
protected FilterConfig filterConfig = null;

public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
this.encoding = filterConfig.getInitParameter("encoding");
}

public void destroy() {
this.encoding = null;
this.filterConfig = null;
}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
try {
// Set Character Encoding
request.setCharacterEncoding(this.encoding);
chain.doFilter(request, response);
}
finally {
// commit transaction and close hibernate session
try {
HibernateSession.commitTransaction();
}
catch (HibernateException e) {
try {
HibernateSession.rollbackTransaction();
}
catch (HibernateException e1) {}
log.error(e);
}
finally {
try {
// close Hibernate Session
HibernateSession.closeSession();
}
catch (HibernateException e) {
log.error(e);
}
}
}
}
}