JSP+Servlet+达梦数据库+JDBC单例 web项目demo.zip

package com.budi.webdemo.jdbc; import java.sql.*; public class DBconn { private final static String url="jdbc:dm://127.0.0.1:5236/test"; private final static String username="SYSDBA"; private final static String password="SYSDBA"; private static Connection conn=null; private static ResultSet rs=null; private static PreparedStatement ps=null; private static DBconn instance=null; static { try { Class.forName("dm.jdbc.driver.DmDriver"); } catch (ClassNotFoundException e) { e.printStackTrace(); } } private DBconn (){} public static DBconn getInstance(){ if(instance==null){ synchronized (DBconn.class){ if(instance==null){ instance=new DBconn(); } } } return instance; } public Connection getConnection() { try { conn=DriverManager.getConnection(url,username,password); } catch (SQLException e) { System.out.println("链接数据库异常***********************"); e.printStackTrace(); } return conn; } public void release(Connection conn, Statement st, ResultSet rs) { if (rs != null) { try { rs.close(); } catch (Exception e) { e.printStackTrace(); } rs = null;//如果rs没有被关闭，就置为空，变成一个垃圾对象，被垃圾回收器回收 } if (st != null) { try { st.close(); } catch (Exception e) { e.printStackTrace(); } st = null; } if (conn != null) { try { conn.close(); } catch (Exception e) { e.printStackTrace(); } } } public static void main(String[] args) { conn=DBconn.getInstance().getConnection(); try { ps=conn.prepareStatement("select * from SYSDBA.USERS "); rs=ps.executeQuery(); while (rs.next()){ System.out.println(rs.getString("id")); } } catch (SQLException e) { e.printStackTrace(); } } }