用策略模式对数据库的增删改操作

这是前一阵写的篇文章，不知道为什么今天登上来没有了，郁闷了好半天，只好重发一遍了。。。。

DataBaseContext


package com;




import java.util.Map;






public class DataBaseContext ...{


DataBaseSuper dbs;




public void setOperate(DataBaseSuper dbs)...{


this.dbs=dbs;


}




public void excuteOperate()...{


this.dbs.operate();


}


}

DataBaseSuper


package com;




import java.sql.Connection;


import java.sql.Statement;


import java.sql.DriverManager;


import java.sql.ResultSet;


import java.util.Map;


import java.util.Iterator;


import java.util.Map.Entry;






public abstract class DataBaseSuper ...{


Connection conn;


Statement stmt;




public void openDB() throws Exception...{


Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();


String url =


"jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=lesson";


String user = "sa";


String password = "123";


conn = DriverManager.getConnection(url, user, password);


stmt = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,


ResultSet.CONCUR_UPDATABLE);


}




public void closeDB() throws Exception...{


stmt.close();


conn.close();


}


public abstract void operate();


}




class Insert extends DataBaseSuper...{


Map map;




public Insert(Map map)...{


this.map=map;


}




public void operate()...{




try ...{


openDB();


String s1="";


String s2="";


Iterator iterator=map.entrySet().iterator();




while(iterator.hasNext())...{


Map.Entry entry= (Map.Entry)iterator.next();


String key=(String)entry.getKey();


String value=(String)entry.getValue();


s1+=key+",";


s2+="'"+value+"'"+",";


}


s1=s1.substring(0,s1.length()-1);


s2=s2.substring(0,s2.length()-1);


String sql="insert into test("+s1+") values("+s2+")";


stmt.executeUpdate(sql);


closeDB();


}




catch (Exception ex) ...{


ex.printStackTrace();


}


}


}




class Delete extends DataBaseSuper...{


Map map;




public Delete(Map map)...{


this.map=map;


}




public void operate()...{




try ...{


openDB();


String s="";


Iterator iterator=map.entrySet().iterator();




while(iterator.hasNext())...{


Map.Entry entry= (Map.Entry)iterator.next();


String key=(String)entry.getKey();


String value=(String)entry.getValue();


s+=key+"='"+value+"' and ";


}


s=s.substring(0,s.length()-5);


String sql="delete from test where "+s;


stmt.executeUpdate(sql);


closeDB();


}




catch (Exception ex) ...{


ex.printStackTrace();


}


}


}




class Update extends DataBaseSuper...{


int id;


Map map;




public Update(int id,Map map)...{


this.id=id;


this.map=map;


}




public void operate()...{




try ...{


openDB();


String s="";


Iterator iterator=map.entrySet().iterator();




while(iterator.hasNext())...{


Map.Entry entry= (Map.Entry)iterator.next();


String key=(String)entry.getKey();


String value=(String)entry.getValue();


s+=key+"='"+value+"',";


}


s=s.substring(0,s.length()-1);


String sql="update test set "+s+" where id='"+id+"'";


stmt.executeUpdate(sql);


closeDB();


}




catch (Exception ex) ...{


ex.printStackTrace();


}


}


}