jdbc的连接

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import java.sql.*;public class JdbcDemo {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stub/*//1.注册加载jdbc驱动,,第一种方式Driver  driver = new oracle.jdbc.driver.OracleDriver();try{DriverManager.registerDriver(driver);}catch(SQLException e){e.printStackTrace();}*/String url = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";String usrname = "scott";String password = "icar";Connection conn = null;Statement st = null;ResultSet rs = null;//try {//1.注册加载jdbc驱动,,,类加载器方式Class.forName("oracle.jdbc.driver.OracleDriver");//2.获取链接conn = DriverManager.getConnection(url,usrname,password);//3.获取执行SQL语句的对象st = conn.createStatement();String sql = "select empno from emp";//4.执行SQL语句rs = st.executeQuery(sql);//5.使用ResultSet对象while(rs.next()){//rs.getInt(columnIndex);//列属性从1开始int empno = rs.getInt("empno");System.out.println(empno);}} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{//6.关闭资源与链接if(rs != null){try {rs.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if(st != null){try {st.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if(conn != null){try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}} 


连接jdbc有5个步骤,①注册加载jdbc驱动,方法是从oracle安装路径中的(E:\app\user\product\11.2.0\dbhome_1\jdbc\lib)下的ojdbc6.jar拷贝到工程项目下,然后build path把类包导到当前项目路径。

第二步  获取链接

String url = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";String usrname = "scott";String password = "icar";
conn = DriverManager.getConnection(url,usrname,password);
 第三步  获取执行sql语句的对象

st = conn.createStatement();String sql = "select empno from emp";

第四步  执行sql语句

rs = st.executeQuery(sql);
while(rs.next()){//rs.getInt(columnIndex);//列属性从1开始int empno = rs.getInt("empno");System.out.println(empno);}

如果知道查询的结果是int类型的,就可以用getInt()来获取结果。getInt有两种,第一种rs.getInt(conlumnIndex);conlumnIndex是属性列的第几列(从1开始);

第二种是rs.getInt(name);第二种是属性列的名字。


第五步  关闭资源服务与链接