Jdbc连接数据库基本步骤

Jdbc连接数据库的基本步骤：

 

package demo.jdbc;

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

public class JdbcConn {
/**
 *JDBC (Java Data Base Connectivity) 数据库连接，有以下几个步骤：
 *1.加载驱动程序   Class.forName(driver);
 *2.创建连接对象  Connection con = DriverManager.getConnection(url,username,password);
 *3.创建sql语句的执行对象 
 *4.执行sql语句
 *5.对执行结果进行处理
 *6.关闭相关连接对象 （顺序跟声明的顺序相反）。
 */
    public static void main(String[] args) {
        String mysqlDriver = "com.mysql.jdbc.Driver";
        String mysqlUrl = "jdbc:mysql://localhost:3306/mybase";
        String mysqlUser = "root";
        String mysqlPass = "111";
        
        String oracleDriver = "oracle.jdbc.driver.OracleDriver";
        String oracleUrl = "jdbc:oracle:thin:@localhost:1521:XE";
        String userName = "zl";
        String passWord = "444";
        String sql = "select ename from emp";
        
        try {
            Class.forName(oracleDriver);
        } catch (ClassNotFoundException e) {
            System.out.println("找不到驱动");
            e.printStackTrace();
        }
        Connection conn = null;
        try {
            conn = DriverManager.getConnection(oracleUrl, userName,passWord );
        } catch (SQLException e) {
            System.out.println("数据库连接错误");
            e.printStackTrace();
        }
        Statement st = null;
        try {
            st = conn.createStatement();
        } catch (SQLException e) {
            System.out.println("创建数据库声明类错误");
            e.printStackTrace();
        }
        boolean flag = false;
        int rows = 0;
        ResultSet rs = null;
        try {
            flag = st.execute(sql);
            rows = st.executeUpdate(sql);
            rs   = st.executeQuery(sql);
            while(rs.next()){
                //通过列的标号来查询数据；
                String name =rs.getString(1);
                //通过列名来查询数据
                String name2 = rs.getString("ename");
                System.out.println(name);
            }
        } catch (SQLException e) {
            System.out.println("测试--");
            e.printStackTrace();
        }
        //关闭数据连接对象
        try {
            if(rs!= null){
                rs.close();
            }
            if(st!= null){
                st.close();
            }
            if(conn!=null){
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}