jdbc数据库连接

1、比如sun公司开发的java链接数据库方法：

class connection{ public Connection getConnection（url，username，password）； //抽象方法由sun公司实现}DiverManger.getConnection();建立java与数据库链接

JDBC接口和数据库厂商的实现：

DriverManger接口：加载驱动

Connection  接口：建立连接

statement   接口：编译sql语句

2、JDBC工作原理和工作过程：

1.加载驱动 mysql  驱动接口：com.mysql.jdbc.Driver oracle 驱动接口：oracle.jdbc.driver.OracleDriver2.建立连接： 通过DriverManger.getConnection(url,user,password); mysql  url:jdbc:mysql://ip地址：数据库名3.编译执行sql语句 String sql=“SQL语句”； statement stmt=con.createSatement(sql);

4.处理结果集

ResultSet  rs=stmt.excuteQuery();ResultSet  rs=stmt.excuteUpdate();

5.关闭连接 con=close();

3、public class Demo3 { public static void main(String[] args) {  try {   Class.forName("com.mysql.jdbc.Driver");  } catch (ClassNotFoundException e) {   System.out.println("加载失败！");  }  Connection con=null;  Statement stmt=null;  ResultSet rs=null;  try {

4、   con=DriverManager.getConnection("jdbc:mysql://localhost:3306/java1707","root","123456");   //编写执行sql语句   stmt=con.createStatement();   //处理结果集   rs=stmt.executeQuery("select * from emp");   //迭代的方式处理结果集   while(rs.next()){    System.out.println("empno"+rs.getInt("empno")+"，ename"+rs.getString("ename"));   }     } catch (SQLException e) {   System.out.println("连接失败！");  }finally{   try {    con.close();   } catch (SQLException e) {    System.out.println("关闭失败！");   }  }   }}

5、import java.io.IOException;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.util.Properties;

/** *  * @author Administrator *  */public class DBUtil { private static Properties properties = new Properties(); private static String driver = null; private static String url = null; private static String username = null; private static String password = null;

6、 // 静态代码块读取配置文件中的信息 static {  try {   properties.load(DBUtil.class.getClassLoader().getResourceAsStream(     "db.properties"));   driver = properties.getProperty("driver");   url = properties.getProperty("url");   username = properties.getProperty("username");   password = properties.getProperty("password");   try {    Class.forName(driver);   } catch (ClassNotFoundException e) {    System.out.println("加载驱动失败！");   }  } catch (IOException e) {   System.out.println("读取文件失败");  } } //建立连接方法 public static Connection getConnection() throws SQLException {  return DriverManager.getConnection(url, username, password); } //关闭连接的方法 public static void closeConnection(Connection con){  try {   con.close();  } catch (SQLException e) {   System.out.println("关闭连接失败！");  } }}