JDBC

The JDBC API is a Java API that can access any kind of tabular data, especially data stored in a Relational Database.

JDBC helps you to write Java applications that manage these three programming activities:

• Connect to a data source, like a database
• Send queries and update statements to the database。
• Retrieve and process the results received from the database in answer to your query

package jdbc;    import java.sql.Connection;  import java.sql.DriverManager;  import java.sql.PreparedStatement;  import java.sql.ResultSet;    public class jdbc_exp {        public static void main(String[] args) {          Connection con = null;// 创建一个数据库连接          PreparedStatement pre = null;// 创建预编译语句对象，一般都是用这个而不用Statement          ResultSet result = null;// 创建一个结果集对象          try          {              Class.forName("oracle.jdbc.driver.OracleDriver");// 加载Oracle驱动程序              System.out.println("开始尝试连接数据库！");              String url = "jdbc:oracle:" + "thin:@10.224.188.188:1521:tonytest";// 127.0.0.1是本机地址，XE是精简版Oracle的默认数据库名              String user = "hr";// 用户名,系统默认的账户名              String password = "CCM%lab123";// 你安装时选设置的密码              con = DriverManager.getConnection(url, user, password);// 获取连接              System.out.println("连接成功！");              String sql = "select * from dept order by 1";// 预编译语句，“？”代表参数              pre = con.prepareStatement(sql);// 实例化预编译语句              result = pre.executeQuery();// 执行查询，注意括号中不需要再加参数              while (result.next())                  // 当结果集不为空时                  System.out.println("deptno: " + result.getInt("deptno") + " dname: "                          + result.getString("dname") + " loc: " + result.getString("loc")                          + " create_date: " + result.getString("create_date"));          }          catch (Exception e)          {              e.printStackTrace();          }          finally          {              try              {                  // 逐一将上面的几个对象关闭，因为不关闭的话会影响性能、并且占用资源                  // 注意关闭的顺序，最后使用的最先关闭                  if (result != null)                      result.close();                  if (pre != null)                      pre.close();                  if (con != null)                      con.close();                  System.out.println("数据库连接已关闭！");              }              catch (Exception e)              {                  e.printStackTrace();              }          }        }    }