自定义Java类实现ID自增，无需数据库主键

public String findId(String table_name)
throws RemoteException
{
String id = table_name + "_id";
String prefix = table_name.substring(0, 2);
Connection conn = DbPoolManager.getConnection();
Statement statement = null;
ResultSet resultset = null;
try
{
statement = conn.createStatement();
resultset = statement.executeQuery("select max(" + id + ") from " + table_name);
resultset.next();
if (resultset.getString(1) != null)
{
String s1 = resultset.getString(1).trim();
int j = (new Integer(s1.substring(2))).intValue() + 1;
String s2 = String.valueOf(j);
StringBuffer stringbuffer = new StringBuffer(prefix + "00000000");
stringbuffer.replace(10 - s2.length(), 10, s2);
id = s2 = stringbuffer.toString();
} else
{
id = prefix + "00000001";
}
}
catch (SQLException sqlexception1)
{
System.out.println(sqlexception1.getMessage());
}