Operations related to android DataBase (Create Table Structure and create table)

Operations related to android DataBase (Create Table Structure and create table)

First, create a base class for the table:

public abstract class DbBaseTable { private static final String TAG = "DbBaseTable"; /**  * @return the DB table name  */ abstract String getName(); /**  * Creates the DB table according to the DB scheme  *  * @param db  */ abstract void onCreate(SQLiteDatabase db);  void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion, String tempName) {           }           void joinColumns(SQLiteDatabase db, String tempName, String tableName) {     DbUtils.joinColumns(db, tempName, tableName);    }}

We use this method to create a table:

Public final class DataBaseClass {private DataBaseClass () {}; public static final int DB_VERSION = 2; static final String DB_FILE = "my. db ";// Put public fields herePublic interface RCMColumns {public static final String account_ID = "account_id"; // INTEGER (long)} public static final class MyTest1Table extends DbBaseTable implements BaseColumns, RCMColumns {private MyTest1Table () {} private static final MyTest1Table sInstance = new MyTest1Table (); static MyTest1Table getInstance () {return sInstance;} private static final String TABLE_NAME = "Mytest1 "; /* Columns */public static final String TEST1 = "test1"; public static final String TEST2 = "test2"; public static final String TEST3 = "test3 "; private static final String CREATE_TABLE_STMT = "create table if not exists" + TABLE_NAME + "(" + _ ID + "integer primary key autoincrement," + account_ID + "INTEGER, "+ TEST1 +" TEXT, "// + TEST2 +" TEXT, "+ TEST3 +" TEXT "+"); "; @ OverrideString getName () {return TABLE_NAME ;} @ overrisponid onCreate (SQLiteDatabase db) mongodb.exe cSQL (CREATE_TABLE_STMT) ;}} public static final class MyTest2Table extends DbBaseTable implements BaseColumns, RCMColumns {private MyTest2Table () {} private static final MyTest2Table sInstance = new MyTest2Table (); static MyTest2Table getInstance () {return sInstance;} private static final String TABLE_NAME = "Mytest2 "; /* Columns */public static final String TEST4 = "test4"; public static final String TEST5 = "test5"; public static final String TEST6 = "test6 "; private static final String CREATE_TABLE_STMT = "create table if not exists" + TABLE_NAME + "(" + _ ID + "integer primary key autoincrement," + account_ID + "INTEGER, "+ TEST4 +" TEXT, "+ TEST5 +" TEXT, "+ TEST6 +" TEXT "+"); "; @ OverrideString getName () {return TABLE_NAME ;} @ overrisponid onCreate (SQLiteDatabase db) mongodb.exe cSQL (CREATE_TABLE_STMT) ;}} static mongohashmap
 
  
SRCMDbTables = new LinkedHashMap
  
   
(); Static {sRCMDbTables. put (MyTest1Table. getInstance (). getName (), MyTest1Table. getInstance (); // sRCMDbTables. put (MyTest2Table. getInstance (). getName (), MyTest2Table. getInstance ());}}
  
 

For android, the execution of some SQL statements depends on SQLiteOpenHelper,

Let's create a subclass of this type:

final class DbHelper extends SQLiteOpenHelper {    private static final String TAG = "[RC]RCMDbHelper";    private static final String TEMP_SUFFIX = "_temp_";        private SQLiteDatabase db_r = null; // readable database    private SQLiteDatabase db_w = null; // writable database        private static DbHelper dbHelper;        private DbHelper(Context context) {        super(context, DataBaseClass.DB_FILE, null, DataBaseClass.DB_VERSION);    }        public static synchronized DbHelper getInstance(Context context) {     if (dbHelper == null) {      dbHelper = new DbHelper(context);     }     return dbHelper;    }    @Override    public void onCreate(SQLiteDatabase db) {                Collection
  
    tables = DataBaseClass.sRCMDbTables.values();        Iterator
   
     iterator = tables.iterator();        System.out.println("====DBHelp oncreate");        try {            db.beginTransaction();            while (iterator.hasNext()) {                iterator.next().onCreate(db);            }            db.setTransactionSuccessful();        } catch (Throwable e) {            //TODO Implement proper error handling                        throw new RuntimeException("DB creation failed: " + e.getMessage());        } finally {            db.endTransaction();        }
   
      }        @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    }        private String getTempTableName(String tableName, Collection
 
   oldTableNames, Set
  
    newTableNames) {        String temp_name_base = tableName + TEMP_SUFFIX;                 if (!oldTableNames.contains(temp_name_base) && !newTableNames.contains(temp_name_base)) {            return temp_name_base;        }            Random random = new Random();        String temp_name;        for (;;) {            temp_name = temp_name_base + random.nextInt();            if (!oldTableNames.contains(temp_name) && !newTableNames.contains(temp_name)) {                return temp_name;            }        }    }        @Override    public synchronized SQLiteDatabase getReadableDatabase() {        if (db_r == null || !db_r.isOpen()) {            try {                
   db_r = super.getReadableDatabase();            } catch (SQLiteException e) {                //TODO Implement proper error handling                db_r = null;                                throw e;            }        }         return db_r;    }        @Override    public synchronized SQLiteDatabase getWritableDatabase() {        if (db_w == null || !db_w.isOpen() || db_w.isReadOnly()) {            try {               
    db_w = super.getWritableDatabase();            } catch (SQLiteException e) {                //TODO Implement proper error handling                db_w = null;                                throw e;            }        }         return db_w;    }}