Database Query designed using a simple factory method (implemented using Java code)

There are six classes in total. The main database class is dbconn. Java, the sub-classes are dbquery. Java and dbupdate. java. The factory classes are dbstore. Java, dbquerystore. Java, and dbupdatestore. java.

 

Dbconn. Java code:

1. Package com. Test. dB;
3. Import com. Test. util. basedatesource;
5. Import javax. SQL. datasource;
7. Import javax. Naming. context;
8. Import javax. Naming. initialcontext;
9. Import javax. Naming. namingexception;
11. Import java. SQL. connection;
12. Import java. SQL. statement;
13. Import java. SQL. preparedstatement;
14. Import java. SQL. resultset;
15. Import java. SQL. sqlexception;
17. Public class dbconn {
18. // Declare database connection, statement, and preparedstatement
19. Connection con;
20. Statement stmt;
21. Preparedstatement psmt;
23. // Obtain the database connection
24. Public void getconn () throws namingexception, sqlexception {
25. Context CTX = new initialcontext ();
26. String strlookup = basedatesource. judi_ SQL;
27. Datasource DS = (datasource) CTX. Lookup (strlookup );
28. Con = Ds. getconnection ();
29. System. Out. println ("database connection enabled ");
30. }
32. // Process the SQL statement of the database. The empty method is used here. The subclass overrides this method.
33. Public void sqlprocess (string SQL ){}
35. // Process the SQL statement of the database. The empty method is used here. The subclass rewrites the method.
36. Public void sqlprocess (string username, string password ){}
38. Public resultset getrs (){
39. Return NULL;
40. }
42. // Close the database connection
43. Public void closecon () throws sqlexception {
44. Con. Close ();
45. System. Out. println ("Database Connection closed ");
46. }
47. }

Dbquery. Java code:

1. Package com. Test. dB;
3. Import java. SQL. resultset;
4. Import java. SQL. sqlexception;
7. Public class dbquery
8. Extends dbconn {
9. Private resultset RS;
11. // This inherits the abstract method of sqlprocess from dbconn. java.
12. Public void sqlprocess (string SQL ){
13. Try {
14. Stmt = con. createstatement ();
15. Rs = stmt.exe cutequery (SQL );
16. System. Out. println ("database queried successfully" + SQL );
17. }
18. Catch (sqlexception e ){
19. E. printstacktrace ();
20. }
21. }
23. Public resultset getrs (){
24. System. Out. println ("returned result set ");
25. Return Rs;
26. }
28. Public void closecon () throws sqlexception {
29. Rs. Close ();
30. Con. Close ();
31. System. Out. println ("the result set and database connection are closed ");
32. }
33. }

Dbupdate. Java code:

1. Package com. Test. dB;
3. Import java. SQL .*;
5. Public class dbupdate
6. Extends dbconn {
8. // This inherits the abstract method of sqlprocess from dbconn. java.
9. Public void sqlprocess (string SQL ){
10. Try {
11. Stmt = con. createstatement ();
12. Stmt.exe cuteupdate (SQL );
13. System. Out. println ("database updated successfully" + SQL );
14. }
15. Catch (sqlexception e ){
16. E. printstacktrace ();
17. }
19. }
20. }

Dbstore. Java code:

1. Package com. Test. dbstore;
3. Import com. Test. DB. dbconn;
5. Import javax. Naming. namingexception;
7. Import java. SQL. sqlexception;
11. Public abstract class dbstore {
12. // Declare the database
13. Dbconn dBc;
15. // Query method of the database to be used for ordering
16. Public dbconn Order (string SQL) throws namingexception, sqlexception {
17. // It is a subclass of DBC new
18. DBC = create ();
19. // Create connections and create connections in a unified manner.
20. DBC. getconn ();
21. // Process the SQL statement here and process it automatically
22. DBC. sqlprocess (SQL );
23. Return dBc;
24. }
26. Public dbconn Order (string username, string password) throws namingexception,
27. Sqlexception {
28. // It is a subclass of DBC new
29. DBC = create ();
30. // Create connections and create connections in a unified manner.
31. DBC. getconn ();
32. // Process the SQL statement here and process it automatically
33. DBC. sqlprocess (username, password );
34. Return dBc;
35. }
37. // Create the database query method to be used. The subclass inherits the secondary abstract method to return the new subclass.
38. Abstract dbconn create ();
39. }

Dbquerystore. Java code:

1. Package com. Test. dbstore;
3. Import com. Test. DB .*;
5. Public class dbquerystore
6. Extends dbstore {
8. // Inherit the abstract method here
9. Dbconn create (){
10. Return new dbquery ();
11. }
12. }

Dbupdatestore. Java code:

1. Package com. Test. dbstore;
3. Import com. Test. DB. dbconn;
4. Import com. Test. DB. dbupdate;
6. Public class dbupdatestore
7. Extends dbstore {
9. // Inherit the abstract method here
10. Dbconn create (){
11. Return new dbupdate ();
12. }
13. }

Use the following code to call a database:

Dbstore DS = new dbupdatestore ();
Dbconn Dc = Ds. Order (SQL );

DC. closeconn ();

 

Dbstore DS = new dbquerystore ();
Dbconn Dc = Ds. Order (SQL );

Resultset rs = Dc. getrs ()

DC. closeconn ();