JDBC连接

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

private static  String driverName ;
private static  String url ;
private static  String userName ;
private static  String userpwd ;

public static Connection con = instance();

public static Connection instance()
{
initDBParameter_Oracle();
return getDBConnection();
}

public static Connection getDBConnection(){
if(null != con )
{
    return con;
}
Connection con=null;
try{
    Class.forName(driverName);
    con = DriverManager.getConnection(url,userName,userpwd);
    if ( con != null){
        System.out.println("conn success !");
    }
}catch(Exception e){
    e.printStackTrace();
}
return con;
}

/**
* 初始化 连结 ACCESS数据 的JDBC连结参数
*/
public static void initDBParameter_Access()
{
driverName = "sun.jdbc.odbc.JdbcOdbcDriver";
//      url = "jdbc:odbc:driver={Microsoft Access Driver (*.mdb)};DBQ="+Cfg.getAccessDBPath();
userName = "";
userpwd = "";
}

/**
* 初始化 连结 ORACLE数据 的JDBC连结参数
*/
public static void initDBParameter_Oracle()
{
driverName = "oracle.jdbc.driver.OracleDriver";
userName = "csmis";
userpwd = "csmis";
//      url ="jdbc:oracle:thin:@127.0.0.1:1521:test";
url ="jdbc:oracle:thin:@127.0.0.1:1521:test";
}

/**
* 初始化 连结 SQL SERVER数据 的jdbc连结参数
*/
public static void initDBParameter_SQLServer()
{
driverName = "com.microsoft.jdbc.sqlserver.SQLServerDriver";
url = "jdbc:microsoft:sqlserver://Localhost:1433;DatabaseName=pubs";
userName = "sa";
userpwd = "sa";
}

/**
* 初始化 连结 SQL SERVER数据 的jdbc连结参数
*/
public static void initDBParameter_MySql()
{
driverName = "com.mysql.jdbc.Driver";
url = "jdbc:mysql://127.0.0.1:3333/test";
userName = "";
userpwd = "";
}

public static Connection conAccess()
{
Connection con=null;
try{
    Class.forName(driverName);
    con = DriverManager.getConnection(url,userName,userpwd);
    if ( con != null){
        System.out.println("conn successed ");
    }
   
}catch(Exception e){
    e.printStackTrace();
}
return con;
}

public static void main(String [] args) throws Exception
{
Connection con = DBConnection.con;
Statement st = con.createStatement();
String sql = "create table b (id varchar2(10));";
st.execute(sql);
//ResultSet rst = st.executeQuery();
}