jdbc学习总结3------javab

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);              }      } 

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;     }           } 

/*
* 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();                                 }                             }                         }                     }                 }             }         }     }      }
*/