SQLite jdbc 单例

package com.tsing.hua.DB;import java.sql.*;public class DB {    public static final String Uri = "jdbc:sqlite:";    public static final String DataBase = "D:\\bbs.db";//数据库所在路径    public static final String ClassName = "org.sqlite.JDBC";    private static String URL = DB.Uri + DB.DataBase;    private static Connection con = null;    static {        try {            Class.forName(DB.ClassName);        } catch (ClassNotFoundException e) {            e.printStackTrace();        }    }    private DB() {        System.out.println("private DB()...");    }    public static Connection getConnection() {        try {            if (con == null) {                con = DriverManager.getConnection(URL);            } else {                return con;            }        } catch (SQLException e) {            e.printStackTrace();            return null;        }        return con;    }    public static void main(String[] args) {        System.out.println(DB.getConnection());        con = DB.getConnection();        String sql = "select * from users";        try {            PreparedStatement ps  = con.prepareStatement(sql);            ResultSet rs = ps.executeQuery();            for( ; rs.next() ; ) {                int id = rs.getInt("uid");;                String Name = rs.getString("name");;                String Password = rs.getString("password");;                System.out.println( " Users : id " + id);                System.out.println( " Users : Name " + Name);                System.out.println( " Users : Password " + Password);            }        }         catch (Exception e) {            e.printStackTrace();        }    }