步骤：

1.注册驱动：

    Class.forName("oracle.jdbc.OracleDriver");

2.建立连接

    String url = "jdbc:oracle:thin:@localhost:1521:xe";
    String user = "用户名";
    String password = "密码";
    Connection conn = 
        DriverManager.getConnection(url, user, password);
    System.out.println("打开到数据库的连接:"+conn);

3.创建statement对象：

    Statement stmt = conn.createStatement();

4.执行SQL：

    String sql ="select id,last_name from s_emp";
    ResultSet rs =stmt.executeQuery(sql);

5.处理结果：

    while(rs.next()) {
        int id = rs.getInt("id");
        String name = rs.getString(2);
        System.out.println(id+" \t "+name);
    }

6.关闭资源：

    rs.close();
    stmt.close();
    conn.close();

实例

package jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class TestJDBC {
    public static void main(String[] args) throws Exception{
        //1.注册驱动
            Class.forName("oracle.jdbc.OracleDriver");
        //2.获取连接
            String url =
                    "jdbc:oracle:thin:@localhost:1521:xe";
            String user = "tom";
            String password = "tom";
            Connection conn =
                DriverManager.getConnection(
                    url, user, password);
            System.out.println("打开到数据库的连接:"+conn);
        //3.创建statement对象
            Statement stmt =
                conn.createStatement();
        //4.执行SQL
            String sql =
                "select id,last_name from s_emp";
            ResultSet rs =
                    stmt.executeQuery(sql);
            System.out.println("id \t last_name");
        //5.处理结果
            while(rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString(2);
                System.out.println(id+" \t "+name);
            }
        //6.关闭资源
            rs.close();
            stmt.close();
            conn.close();
    }
}