JDBC Learning Note (16): Using Reflection Technology Award query results encapsulated as objects

1  PackageCom.xxyh.jdbc;2 Importjava.lang.reflect.InvocationTargetException;3 ImportJava.lang.reflect.Method;4 Importjava.sql.Connection;5 Importjava.sql.PreparedStatement;6 ImportJava.sql.ResultSet;7 ImportJava.sql.ResultSetMetaData;8 Importjava.sql.SQLException;9 ImportCom.xxyh.jdbc.domain.User;Ten  Public classOrmtest { One      A      Public Static voidMain (string[] args)throwsillegalaccessexception, IllegalArgumentException, InvocationTargetException, SQLException { -User user = GetUser ("SELECT ID as ID, name as name, birthday as birthday, money as money from user where id=1"); - System.out.println (user); the     } -      -     StaticUser getUser (String sql)throwsSQLException, Illegalaccessexception, IllegalArgumentException, invocationtargetexception { -Connection conn =NULL; +PreparedStatement PS =NULL; -ResultSet rs =NULL; +         Try { Aconn =jdbcutils.getconnection (); atPS =conn.preparestatement (SQL); -rs =ps.executequery (); -              -ResultSetMetaData RSMD =Rs.getmetadata (); -             intCount =Rsmd.getcolumncount (); -string[] Colnames =NewString[count]; in              for(inti = 1; I <= count; i++)  -COLNAMES[I-1] =Rsmd.getcolumnlabel (i); to               +User User =NULL; -              the             if(Rs.next ()) { *user =NewUser (); $                  for(inti = 0; i < colnames.length; i++) {Panax NotoginsengString colname =Colnames[i]; -String methodName = "Set" +colname; theMethod[] Methods =User.getclass (). GetMethods (); +                      for(Method method:methods) { A                         if(Methodname.equals (Method.getname ())) { the method.invoke (User, Rs.getobject (colname)); +                         } -                     } $                 } $             } -             returnuser; -}finally { the Jdbcutils.close (RS, PS, conn); -         }Wuyi          the     } -}

"Run result": [1,zhangs,1985-01-01,360.0] Note: The output is shown as above because the ToString method of user is overridden:

@Override  Public  String toString () {    return "[" + getId () + "," + getName () + "," + getbirthday () + "," + Getmoney () + "]";}

By using generics to improve the generality of the program, the GetObject method is independent of the specific class:

1  PackageCom.xxyh.jdbc;2 Importjava.lang.reflect.InvocationTargetException;3 ImportJava.lang.reflect.Method;4 Importjava.sql.Connection;5 Importjava.sql.PreparedStatement;6 ImportJava.sql.ResultSet;7 ImportJava.sql.ResultSetMetaData;8 Importjava.sql.SQLException;9 ImportCom.xxyh.jdbc.domain.User;Ten  Public classOrmtest { One      A      Public Static voidMain (string[] args)throwsillegalaccessexception, IllegalArgumentException, InvocationTargetException, SQLException, instantiationexception { -User user = (user) GetObject ("SELECT ID as ID, name as name, birthday as birthday, money as money from user where id=2", Us Er.class); - System.out.println (user); the     } -      -     StaticObject getObject (String sql, class<?> clazz)throwsSQLException, Illegalaccessexception, IllegalArgumentException, InvocationTargetException, instantiationexception { -Connection conn =NULL; +PreparedStatement PS =NULL; -ResultSet rs =NULL; +         Try { Aconn =jdbcutils.getconnection (); atPS =conn.preparestatement (SQL); -rs =ps.executequery (); -              -ResultSetMetaData RSMD =Rs.getmetadata (); -             intCount =Rsmd.getcolumncount (); -string[] Colnames =NewString[count]; in              for(inti = 1; I <= count; i++)  -COLNAMES[I-1] =Rsmd.getcolumnlabel (i); to               +Object object =NULL; -Method[] Methods =clazz.getmethods (); the             if(Rs.next ()) { *Object = Clazz.newinstance ();//Create an Object $                  for(inti = 0; i < colnames.length; i++) {Panax NotoginsengString colname =Colnames[i]; -String methodName = "Set" +colname; the                      for(Method method:methods) { +                         if(Methodname.equals (Method.getname ())) { A Method.invoke (object, Rs.getobject (colname)); the                         } +                     } -                 } $             } $             returnobject; -}finally { - Jdbcutils.close (RS, PS, conn); the         } -         Wuyi     } the}

"Run result": [2,lisi,1986-01-01,900.0]

JDBC Learning Note (16): Using Reflection Technology Award query results encapsulated as objects