Android Database (publish database with APK)

Read database + database version update

Attention:

A, place the database with the APK released under the/res/raw path under Android engineering.

b, when the database file is stored on the phone, the path is/data/data/your package name/databases, and the other path will go wrong.

Sqliteopenhelper is inherited when you need to create a new database directly in the project, but this article is about publishing the database with the APK, so there's no need to inherit Sqliteopenhelper, But also need to do a layer of test.db packaging, in the Test.db wrapper class to operate the database.

The process of writing a program often changes the structure of the database, you can use the database version number to determine whether the database on the phone should be updated, SQLite database user_version provides this help. The following command can change the user_version,user_version of the database must be of integer type.

PRAGMA [Database.] User_version = 2;

Here is the implementation code, which includes writing the database to the phone and updating the database.

1  Public classtestsqldatabase{2     3     Private Static FinalString Database_path = "/data/data/your.package.name/databases";4 5     Private Static Final intdatabase_version = 0;6 7     Private Static FinalString database_name = "Test.db";8     9     Private StaticString outfilename = Database_path + "/" +database_name;Ten      One     Privatecontext context; A  - 　　　　  Privatesqlitedatabase database; -      the      PublicTestsqldatabase (Context context) { -          This. Context =context; -          -File File =NewFile (outfilename); +         if(File.exists ()) { -Database = Sqlitedatabase.openorcreatedatabase (Outfilename,NULL); +             if(Database.getversion ()! =database_version) { A database.close (); at File.delete ();  -             } -         } -         Try { - builddatabase (); -}Catch(Exception e) { in e.printstacktrace (); -         } to          +     } -  the     Private voidBuilddatabase ()throwsexception{ *InputStream myinput =context.getresources (). Openrawresource (r.raw.test); $File File =NewFile (outfilename);Panax Notoginseng          -File dir =NewFile (database_path); the         if(!dir.exists ()) { +             if(!Dir.mkdir ()) { A                 Throw NewException ("Create failed"); the             } +         } -          $         if(!file.exists ()) {             $             Try { -OutputStream Myoutput =NewFileOutputStream (outfilename); -                  the                 byte[] buffer =New byte[1024]; -                 intlength;Wuyi                  while(length = myinput.read (buffer)) >0){ theMyoutput.write (buffer, 0, length); -                 } Wu myoutput.close (); - myinput.close (); About}Catch(Exception e) { $ e.printstacktrace (); -             } -          -         } A     } +}

Android Database (publish database with APK)