JDBC 初步

1 .

JDBC  即 java database connection

 

java 与数据库连接的一项技术,就我现在认为的.

 

首先是,要在工作环境上加入,D:/oracle/product/10.1.0/Db_2/jdbc/lib 中的classes12.jar 文件.

 

第二步,下面写一个jdbc 的初步应用小程序好了.

import java.sql.*; public class BlogJDBC { public static void main(String[] args) { Connection conn = null; Statement stmt = null; String sql = null; ResultSet rs = null; try { Class.forName("oracle.jdbc.driver.OracleDriver"); //获取数据库连接的驱动,即载入驱动 String url = "jdbc:oracle:thin:@192.168.1.12:1521:orcl"; conn = DriverManager.getConnection(url,"scott","tiger"); //建立数据库连接,即注册驱动,,, 为固定连接串,@+hostip+端口号+数据库sid //后面两个字符串分别为 数据库的用户名 . 密码 stmt = conn.createStatement(); //创建Statement对象 sql = "select * from dept"; rs = stmt.executeQuery(sql); //调用并执行SQL语句 while(rs.next()) { System.out.println(rs.getString(1)); //访问ResultSet中的记录集并从中取出记录 } } catch(ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e1) { e1.printStackTrace(); } finally { try { if(rs != null) { rs.close(); rs = null; } if(stmt != null) { stmt.close(); stmt = null; } if(conn != null) { conn.close(); conn = null; } //依次关闭ResultSet、Statement和Connection对象 } catch(SQLException e) { e.printStackTrace(); } } } } 

 

 

2 .

statement 包括 PreparedStatement 和 CallableStatement

 

preparedStatement 能进行如下操作:

pstmt = conn.prepareStatement ("insert into dept2 values (?, ?, ?)"); pstmt.setInt(1, deptno); pstmt.setString(2, dname); pstmt.setString(3, loc); pstmt.executeUpdate();

一般编程中多使用preparedStatement

 

CallableStatement 能进行如下操作:

CallableStatement cstmt = conn.prepareCall ("{call p(?, ?, ?, ?)}"); cstmt.registerOutParameter(3, Types.INTEGER); cstmt.registerOutParameter(4, Types.INTEGER); cstmt.setInt(1, 3); cstmt.setInt(2, 4); cstmt.setInt(4, 5); cstmt.execute();

 

3 .

 

以下是一个批处理的下程序

import java.sql.*; public class TestTransaction { public static void main(String[] args) { Connection conn = null; Statement stmt = null; try { Class.forName("oracle.jdbc.driver.OracleDriver"); conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:SXT", "scott", "tiger"); conn.setAutoCommit(false); stmt = conn.createStatement(); stmt.addBatch("insert into dept2 values (51, '500', 'haha')"); stmt.addBatch("insert into dept2 values (52, '500', 'haha')"); stmt.addBatch("insert into dept2 values (53, '500', 'haha')"); stmt.executeBatch(); conn.commit(); conn.setAutoCommit(true); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch(SQLException e) { e.printStackTrace(); try { if(conn != null) { conn.rollback(); conn.setAutoCommit(true); } } catch (SQLException e1) { e1.printStackTrace(); } }finally { try { if(stmt != null) stmt.close(); if(conn != null) conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } }