A simple database access application

File 1:
First, move the parent class of the main program!
/*
* Date: 2004-11-20
* Author: zhangyu6050;
* Todo:
* Bugs:
*/
Package sd;
 
Import javax. swing .*;
Import java. awt .*;
Import java. awt. event .*;

Public abstract class MyQQPan extends JFrame implements ActionListener
{
JTextArea textreceive = new JTextArea ();
JTextArea textsend = new JTextArea ("select * from Employees ");
JButton button = new JButton ("Send ");
Public MyQQPan ()
{
// Init controls
SetTitle ("query framework ");
SetBounds (50, 50, 500,400 );
GetContentPane (). setLayout (null );

Getcontentpane (). Add (textreceive );
Getcontentpane (). Add (textsend );
Getcontentpane (). Add (button );

Button. addactionlistener (this );

Textreceive. setbounds (0, 0, 450,300 );
Textsend. setbounds (10,320,350, 60 );
Button. setbounds (370,320, 70, 30 );
}

 
 
Public abstract void actionreceivmed (actionevent event );


}
File 2:
Below is the main program!
/*
* Date: 2004-11-19
* Author: zhangyu6050;
* Todo:
* Bugs:
*/
Package SD;
// TextAreaDemo. java
Import java. awt .*;
Import java. awt. event. ActionEvent;
Import java. awt. event. ActionListener;
Import java. SQL. ResultSet;
Import java. SQL. ResultSetMetaData;
Import java. SQL. SQLException;

Import javax. swing .*;
Import sd. Mysql;
 
Public class Myframe extends MyQQPan {
Private String SQL;
Private String rsult;
// Private int row; // The column to be retrieved
Public void actionreceivmed (ActionEvent e ){
If (e. getSource () instanceof JButton ){
SQL = textsend. getText ();
// Row = Character. getNumericValue (SQL. charAt (SQL. length ()-1); // obtain the number of columns to be retrieved!
// InitRsult ();
Methods. ting (SQL); // This class integrates some common Methods!
Rsult = Methods. rStr;
Textreceive. setText (rsult );
}
}

Public static void main (String [] args ){
Myframe mf = new Myframe ();
Mf. setVisible (true );
}

}

 
File 3:

Database Connection class, and integrated related methods in Facade mode!

/*
* Date: 2004-11-17
* Author: zhangyu6050;
* Todo: a database encapsulation class used:
* Getting database connections
* Select the database through the accepted SQL statement and return the result
* The following judgment should be made during the period: 1 If SQL is used for query :,,,,
* 2 If SQL is used to update :,,,,
*
* Bugs:
* Improvement: Implementation interface: sqlQuery;
* It mainly inherits constants such as ERROR and SUCCESS!
*/
Package sd;
 
Import java. util. List;
Import java. SQL .*;
Public class Mysql {
Private String dirverName = "com. microsoft. jdbc. sqlserver. SQLServerDriver ";
Private String URL = "jdbc: microsoft: sqlserver: // localhost: 1433; DatabaseName = Northwind ";
Private String password = "sa ";
Private String userName = "sa ";
Private Connection conn = null;
Private Statement stmt = null;
Private PreparedStatement prepstmt = null;
Public void getDataSource (){
Try {
Class. forName (dirverName );
Conn = DriverManager. getConnection (URL, userName, password );

} Catch (Exception e ){
// Connection error!
System. out. print ("connection error! ");
E. printStackTrace ();
}
}
Public Mysql (){

Try {
Getdatasource ();
Stmt = conn. createstatement ();
} Catch (sqlexception e ){
System. Out. Print ("conn. createstatement () error! ");
E. printstacktrace ();
}
}

Public MySQL (string aqurey ){
Try {
Stmt = conn. createstatement ();
Preparestatement (aqurey );
} Catch (sqlexception e ){
System. Out. Print ("conn. createstatement () error! ");
E. printstacktrace ();
}

}
Public resultset find (string aquery) throws sqlexception {
If (stmt = NULL) return NULL;
String query = aquery;
// It is best to pass some checks to prevent SQL injection!
Return stmt.exe cuteQuery (query );
}
Public ResultSet find () throws SQLException {
If (prepstmt = null) return null;
Return prepstmt.exe cuteQuery ();
}
Public String find (String aquery, int row) throws SQLException {
ResultSet r = this. find (aquery );
String rs = "";
While (r. next ())
Rs + = (String) r. getObject (row) + "/n ";
Return rs;

}
Public void prepareStatement (String SQL) throws SQLException {
Prepstmt = conn. prepareStatement (SQL );
}
Public void close () throws SQLException {
If (prepstmt! = Null) prepstmt. close ();
If (stmt! = Null) prepstmt. close ();
}

}
File 4:
Method set for processing database results
/*
* Date: 2004-11-18
* Author: zhangyu6050;
* Todo: method set for processing database results!
* Bugs:
*/
Package sd;

Import java. SQL. ResultSet;
Import java. SQL. ResultSetMetaData;
Import java. SQL. SQLException;
 
 
Public class Methods {
Static Mysql q1 = new Mysql ();
Static ResultSet r;
Static String rStr = "";
Public static void ting (String SQL) {// retrieves the result String based on SQL in table format

Try {
// You can use a regular expression to determine!
If (SQL = null | SQL. equals ("") r = q1.find ("select EmployeeID, LastName from employees ");
Else r = q1.find ("select EmployeeID, LastName from employees ");
ResultSetMetaData rsmd = r. getMetaData ();
Int columnCount = rsmd. getColumnCount ();
For (int I = 1; I <= columnCount; I ++ ){
RStr + = rsmd. getColumnName (I) + "/t ";
}
RStr + = "/n ";
While (R. Next ()){
For (INT I = 1; I <columncount + 1; I ++ ){
Rstr + = (R. GetObject (I) + "/T ");
}
Rstr + = "/N ";
}
} Catch (sqlexception e ){
E. printstacktrace ();
}

}
/* Public static void main (string [] ARGs ){
String S = "123 ";
Int I = character. getnumericvalue (S. charat (2 ));
Ting (null );

System. Out. println (rstr );
}
*/
}

Not complete.
Please advise :)