Database-related operations: such as connection, query, addition, deletion, modification, and paging display

Database-related operations: such as connection, query, addition, deletion, modification, and paging display
 
Package study. database;

/**
* <P> Title: jsp (preferred for SUN Enterprise Applications) model learning </p>
* <P> Description: database related operations, such as connection, query, addition, deletion, and modification. </p>
* <P> Copyright: Copyright (c) 2004 </p>
* <P> Company: </p>
* @ Author Li Yansheng
* @ Version 1.0
*/
Import java. SQL .*;
Import java. io .*;
Import java. util .*;

Public class Operation {
// Database driver
Private String strDriver = "";
// Database connection string
Private String strURL = "";
// Database username
Private String username = "";
// Database Password
Private String password = "";

Private Connection conn = null;
Private Statement stmt = null;
ResultSet rs = null;

/** Read database configuration information
*/
Private void loadProp (){
InputStream is = getClass (). getResourceAsStream ("/setup.txt ");
Properties props = new Properties ();

Try {
Props. load (is );
} Catch (Exception e ){
System. err. println ("the configuration file cannot be read. Ensure that setup.txt is in the path specified by classes ");
}

Enumeration propNames = props. propertyNames ();
While (propNames. hasMoreElements ()){
String name = (String) propNames. nextElement ();
If (name. endsWith (". driver ")){
String poolName = name. substring (0, name. lastIndexOf ("."));
StrDriver = props. getProperty (poolName + ". driver ");
StrURL = props. getProperty (poolName + ". url ");
Username = props. getProperty (poolName + ". user ");
Password = props. getProperty (poolName + ". password ");
}
}
}

/** Connect to the database when creating an Operation object
*/
Public Operation (){
// Read database configuration information
LoadProp ();

Try {
Class. forName (strDriver );
} Catch (java. lang. ClassNotFoundException e ){
System. err. println ("database connection error:" + e. getMessage ());
}

Try {
Conn = DriverManager. getConnection (strURL, username, password );
} Catch (SQLException ex ){
System. err. println ("database connection error:" + ex. getMessage ());
}
}

/** Database Query
* SQL: SQL query statement
*/
Public ResultSet query (String SQL ){
Try {
Stmt = conn. createStatement ();
Rs1_stmt.exe cuteQuery (SQL );
} Catch (SQLException ex ){
System. err. println ("database query error:" + ex. getMessage ());
}

Return rs;
}

/** Add, modify, and delete Databases
* SQL: SQL statement
*/
Public void update (String SQL ){
Try {
Stmt = conn. createStatement ();
Stmt.exe cuteUpdate (SQL );
} Catch (SQLException ex ){
System. err. println ("database update error:" + ex. getMessage ());
}
}

/** Get the total number of records in the query results
* Rs: query result set
*/
Public int totalRecord (ResultSet rs) throws Exception {
Int total = 0;
// Move the pointer to the last record
Rs. last ();
Total = rs. getRow ();
Rs. first ();

Return total;
}

/** Display by PAGE
* CurrPage: Current page number
* PageSize: page size
* PageCount: Total number of pages
* Filename: the name of the file that uses pagination (which must be followed ?, Multiple parameters are separated by commas (,), and parameters are ended with commas)
* Http://www.knowsky.com/return string: <a href = "filename? Page = Current page number ">
*/
Public String showPages (int currPage, int pageSize, int pageCount, String filename ){
String addr;

Addr = "<table width = 100% border = 0 align = center cellpadding = 0 cellspacing = 0> <form method = Post name = pageform> <tr> <td> <div align = right> current <strong> <font color = red> "+ currPage +" </font> </strong> page "+
"Total <strong> <font color = red>" + pageCount + "</font> </strong> pages <strong> <font color = red>" + pageSize + "</font> </strong> entries ";