1.测试类的内容：
在包：com.hanchao.test中
代码语言：javascript复制package com.hanchao.test; import com.hanchao.dao.UserDao; import com.hanchao.entity.User; /** * 测试jdbc的类（javaBean DAO） * @author hanlw * 2012-07-09 */ public class Test { /** * 1.什么是JavaBean? * 它要满足两个条件：<1>.私有化属性;<2>.公开访问方法(setter and getter) * * 2.javabean又名：entity实体类、pojo、vo * * 3.DAO = data access object （封装了对一个表的所有CRUD操作！！） * DAO中方法的本质是将对象(entity)类和数据库进行交互。 */ public static void main(String[] args) { /** * 1.insert()操作测试 */ /* UserDao userDao = new UserDao(); User user = new User(); user.setUsername("chenchen"); user.setAddress("jiangsu"); userDao.insert(user); */ /** * 2.update()操作 */ /* UserDao userDao = new UserDao(); User user = new User(); user.setId(20); user.setAddress("yancheng1"); user.setUsername("iloveyou"); userDao.update(user); */ /** * delete()操作 */ // UserDao userDao = new UserDao(); // userDao.delete(21); /** * retrieve()操作 */ UserDao userDao = new UserDao(); userDao.retrieve(22); } } 2.实体类的写法：com.hanchao.entity
代码语言：javascript复制package com.hanchao.entity; /** * 实体类 * @author hanlw * 2012-07-09 */ public class User { /** * 1.实体类的类名一般和数据库中的相应的表名相同：如t_user对应的实体类为User * * 2.实体类中的属性一般与表中的列名相同：如下 * * 3.写属性的getter 和 setter方法 */ private int id; private String username; private String address; //下面是setter...getter.. public int getId() { return id; } public void setId(int id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } } 3.dao的写法：com.hanchao.dao
代码语言：javascript复制/*
* 提示：该行代码过长，系统自动注释不进行高亮。一键复制会移除系统注释
* package com.hanchao.dao; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import com.hanchao.entity.User; /** * User类对应的Dao * @author hanlw * 2012-07-09 */ public class UserDao { /** * 说明： * 1.某个实体类对应的Dao一般写成(类名 Dao),如User类对应Dao类为：UserDao * * 2.Dao中封装了对对应实体类的所有的CRUD的操作！！如下： */ /** * 1.对mysql的insert操作 */ public int insert(User user) { Connection con = null; PreparedStatement sta = null; int rows = 0; try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb","root","root"); String sql = "insert into t_user(username,address) value(?,?)"; sta = con.prepareStatement(sql); sta.setString(1, user.getUsername()); sta.setString(2, user.getAddress()); rows = sta.executeUpdate(); if(rows > 0) { System.out.println("operate successfully!!"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { if(sta != null) { try { sta.close(); } catch (SQLException e) { e.printStackTrace(); } finally { if(con != null) { try { con.close(); } catch (SQLException e) { e.printStackTrace(); } } } } } return rows; } /** * 2.对mysql的update操作 */ public int update(User user) { Connection con = null; PreparedStatement sta = null; int rows = 0; try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb","root","root"); String sql = "update t_user set address=?,username=? where id=?"; sta = con.prepareStatement(sql); sta.setString(1, user.getAddress()); sta.setString(2, user.getUsername()); sta.setInt(3, user.getId()); rows = sta.executeUpdate(); if(rows > 0) { System.out.println("ok"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { if(sta != null) { try { sta.close(); } catch (SQLException e) { e.printStackTrace(); } finally { if(con != null) { try { con.close(); } catch (SQLException e) { e.printStackTrace(); } } } } } return rows; } /** * 3.对mysql的delete()操作 */ public int delete(int id) { Connection con = null; PreparedStatement sta = null; int rows = 0; try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb","root","root"); String sql = "delete from t_user where id=?"; sta = con.prepareStatement(sql); sta.setInt(1, id); rows = sta.executeUpdate(); if(rows > 0) { System.out.println("ok,ok,ok"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { if(sta != null) { try { sta.close(); } catch (SQLException e) { e.printStackTrace(); } finally { if(con != null) { try { con.close(); } catch (SQLException e) { e.printStackTrace(); } } } } } return rows; } /** * 4.retrieve()操作 */ public void retrieve(int id) { Connection con = null; PreparedStatement sta = null; ResultSet rs = null; try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb","root","root"); String sql = "select id,username,address from t_user where id=?"; sta = con.prepareStatement(sql); sta.setInt(1, id); rs = sta.executeQuery(); if(rs.next()) { int idd = rs.getInt("id"); String username = rs.getString("username"); String adrress = rs.getString("address"); System.out.println(idd "t" username "t" adrress); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally { if(rs != null) { try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } finally { if(sta != null) { try { sta.close(); } catch (SQLException e) { e.printStackTrace(); } finally { if(con != null) { try { con.close(); } catch (SQLException e) { e.printStackTrace(); } } } } } } } } }
*/看dao中的内容，我们发现几个方法中的代码有很多重复的！！所以在下一篇文章中，我们要对代码进行优化！
