多线程程序中操作数据库的问题，线程数量比较多！

[qdcomn]

写了一个多线程程序，同时会有很多线程执行某条SQL语句，程序执行一会儿后，会报空指针错误（java.lang.NullPointerException），该如何处理？？？

SQL就是简单的语句：UPDATE TABLE SET name = 'zhangshan'

DB db = new DB();
ArrayList urlList = db.update(StrSQL);


DB代码如下（使用的Tomcat连接池）：
private String jndiName = null;
private Connection conn = null;
private PreparedStatement psmt = null;
private ResultSet rs = null;
private ResultSetMetaData rsmd = null;

public DB(){
jndiName = "java:comp/env/www_yuqing_2009/jdbcmssql";
boolean isConnValid = false;
try {
Context ctx = new InitialContext();
DataSource ds = (DataSource) ctx.lookup(jndiName);
conn = ds.getConnection();
} catch (NamingException e) {
logger.debug("Can not find JNDI Name, datesource configuration error!");

} catch (SQLException e) {
logger.debug("Can not connect to database, please check the path and the username and the password!");

}
}



public int update(String strSql) throws SQLException {
int result = 0;
try{
this.psmt = this.conn.prepareStatement(strSql);
result = this.psmt.executeUpdate();

this.psmt.close();
}catch(SQLException e){
if(this.conn.getAutoCommit())
this.close();
throw new SQLException(this.MakeErrMsg(strSql,e));
}
return result;
}

[Trinx]

楼主没发现哪句抛空指针异常了

[qdcomn]

我的线程比较多，可能同时会有几十个线程执行一条SQL语句