Java EE WEB工程师培训-JDBC+Servlet+JSP整合开发之02.JDBC Connection

Class.forName( "com.mysql.jdbc.Driver");    
Connection conn = DriverManager.getConnection( "jdbc:mysql://localhost:3306/michael_db", "root", "mysqladmin");

package com.michael.jdbc;    

import java.sql.Connection;    
import java.sql.DriverManager;    

public  class ConnectionUtil {    

         /**    
         * @param args    
         */    
         public Connection getConnection(){    
                Connection conn =  null;    
                 try {    
                         //Class.forName加载驱动    
                        Class.forName( "com.mysql.jdbc.Driver");    
                         //DriverManager获得连接    
                        conn = DriverManager.getConnection( "jdbc:mysql://localhost:3306/jdbc_db","root","mysqladmin");    
                        return conn;    
                } catch (Exception e) {    
                        e.printStackTrace();    
                }    
                return null;    
        }    

} 

package com.michael.main;    

import com.michael.jdbc.ConnectionUtil;    

public  class Main {    

         /**    
         * @param args    
         */    
         public  static  void main(String[] args) {    
                ConnectionUtil cu =  new ConnectionUtil();    
                System.out.print(cu.getConnection());    
        }    

} 

package com.michael.jdbc;    

import java.sql.Connection;    
import java.sql.DriverManager;    

public  class ConnectionUtil {    
         //第一种方法    
         public Connection getConnection(){    
                Connection conn =  null;    
                 try {    
                         //Class.forName加载驱动    
                        Class.forName( "com.mysql.jdbc.Driver");    
                         //DriverManager获得连接    
                        conn = DriverManager.getConnection( "jdbc:mysql://localhost:3306/jdbc_db","root","mysqladmin");    
                        return conn;    
                } catch (Exception e) {    
                        e.printStackTrace();    
                }    
                return null;    
        }    
        //第二种方法    
        public Connection getConnection(String driver,String url,String user,String password){    
                Connection conn = null;    
                try {    
                        //Class.forName加载驱动    
                        Class.forName(driver);    
                        //DriverManager获得连接    
                        conn = DriverManager.getConnection(url,user,password);    
                        return conn;    
                } catch (Exception e) {    
                        e.printStackTrace();    
                }    
                return null;    
        }    

} 

package com.michael.main;    

import com.michael.jdbc.ConnectionUtil;    

public  class Main {    

         /**    
         * @param args    
         */    
         public  static  void main(String[] args) {    
                ConnectionUtil cu =  new ConnectionUtil();    
                 //第一种方法    
                System.out.println(cu.getConnection());    
                 //第二种方法    
                System.out.println(cu.getConnection( "com.mysql.jdbc.Driver", "jdbc:mysql://localhost:3306/jdbc_db","root","mysqladmin"));    
        }    

} 

driver=com.mysql.jdbc.Driver    
url=jdbc:mysql: //localhost:3306/jdbc_db    
user=root    
password=mysqladmin

package com.michael.jdbc;    

import java.sql.Connection;    
import java.sql.DriverManager;    
import java.util.Properties;    

public  class ConnectionUtil {    
         //第一种方法    
         public Connection getConnection(){    
                Connection conn =  null;    
                 try {    
                         //Class.forName加载驱动    
                        Class.forName( "com.mysql.jdbc.Driver");    
                         //DriverManager获得连接    
                        conn = DriverManager.getConnection( "jdbc:mysql://localhost:3306/jdbc_db","root","mysqladmin");    
                        return conn;    
                } catch (Exception e) {    
                        e.printStackTrace();    
                }    
                return null;    
        }    
        //第二种方法    
        public Connection getConnection(String driver,String url,String user,String password){    
                Connection conn = null;    
                try {    
                        //Class.forName加载驱动    
                        Class.forName(driver);    
                        //DriverManager获得连接    
                        conn = DriverManager.getConnection(url,user,password);    
                        return conn;    
                } catch (Exception e) {    
                        e.printStackTrace();    
                }    
                return null;    
        }    
        //第三种方法    
        public Connection openConnection(){    
                String driver = "";    
                String url = "";    
                String user = "";    
                String password = "";    
                Properties prop = new Properties();    
                Connection conn = null;    
                try {    
                        //加载属性文件    
                        prop.load(this.getClass().getClassLoader().getResourceAsStream("DBConfig.properties"));    
                        driver = prop.getProperty("driver");    
                        url = prop.getProperty("url");    
                        user = prop.getProperty("user");    
                        password = prop.getProperty("password");    
                        //Class.forName加载驱动    
                        Class.forName(driver);    
                        //DriverManager获得连接    
                        conn = DriverManager.getConnection(url,user,password);    
                        return conn;    
                } catch (Exception e) {    
                        e.printStackTrace();    
                }    
                return null;    
        }    

} 

package com.michael.main;    

import com.michael.jdbc.ConnectionUtil;    

public  class Main {    

         /**    
         * @param args    
         */    
         public  static  void main(String[] args) {    
                ConnectionUtil cu =  new ConnectionUtil();    
                 //第一种方法    
                System.out.println( "第一种方法:"+cu.getConnection());    
                 //第二种方法    
                System.out.println( "第二种方法:"+cu.getConnection( "com.mysql.jdbc.Driver", "jdbc:mysql://localhost:3306/jdbc_db","root","mysqladmin"));    
                //第三种方法    
                System.out.println("第三种方法:"+cu.openConnection());    
        }    

}