模板模式以及回呼函數__函數

import java.sql.PreparedStatement;/** * PreparedStatement回調介面 *  * @author 姚磊 *  */public interface PreparedStatementCallback {/** *  * @param pstm * @return * @throws Exception */Object doInPreparedStatement(PreparedStatement pstm) throws Exception;}

public interface ResultSetCallback{ /**  *   * @param rs  * @return  * @throws Exception  */ Object doInResultSet(ResultSet rs) throws Exception;}

public  class JdbcTemplate {  /**  * 執行資料庫查詢操作,不考慮資料庫事務問題.  * 這裡基於java.sql.Statement介面實現有關操作  * @param callback  * @param sql  * @return  * @throws Exception  */ public Object executeQuery(ResultSetCallback callback,String sql) {  Connection conn = null;  Object obj = null;  Statement stm  =null;  ResultSet rs = null;  try{     conn = DBUtil.getConnection();     stm = conn.createStatement();     rs = stm.executeQuery(sql);     obj = callback.doInResultSet(rs);     }  catch(Exception e){   e.printStackTrace();  }  finally{   //close ResultSet object   if(rs!=null)   try{    rs.close();   }   catch(Exception e){    e.printStackTrace();   }   //close Statement object   if(stm!=null)   try{    stm.close();   }   catch(Exception e){    e.printStackTrace();   }   //close Connection object   DBUtil.closeConnection(conn);  }  return obj; }   /**  * 執行資料庫更新操作,需要考慮事務問題  * 這裡基於java.sql.PreparedStatement介面實現有關操作  * @param callback  * @param sql  * @return  * @throws Exception  */ public Object executeUpdate(PreparedStatementCallback callback,String sql){  Connection conn = null;  Object obj = null;  PreparedStatement pstm  =null;  try{     conn = DBUtil.getConnection();     conn.setAutoCommit(false); //設定非自動認可事務     pstm = conn.prepareStatement(sql);     obj = callback.doInPreparedStatement(pstm);     conn.commit();  //提交事務     }  catch(Exception e){   e.printStackTrace();   try{       conn.rollback();//復原事務    }catch(Exception ex){       ex.printStackTrace();    }  }  finally{   //close PreparedStatement object   if(pstm!=null)    try{     pstm.close();    }    catch(Exception e){     e.printStackTrace();    }   //close Connection object    DBUtil.closeConnection(conn);  }  return obj; }  }

 

public User findUser(String name, String passwd) {final String sql = "select * from admin where name ='"+name+"' and passwd='"+passwd+"'";LogUtil.log(sql);return (User) new JdbcTemplate().executeQuery(new ResultSetCallback(){public Object doInResultSet(ResultSet rs) throws Exception {User admin = null;if(rs.next()){admin = new User();admin.setName(rs.getString("name"));admin.setPasswd(rs.getString("passwd"));}return admin;}},sql);}