先建立一个table的基类:
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);
}
}
我们通过这种方式来建立表:
public final class DataBaseClass {
private DataBaseClass() {};
public static final int DB_VERSION = 2;
static final String DB_FILE = "my.db";
<strong>//这里放公共的字段</strong>
public 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"
+ ");";
@Override
String getName() {
return TABLE_NAME;
}
@Override
void onCreate(SQLiteDatabase db) {
db.execSQL(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"
+ ");";
@Override
String getName() {
return TABLE_NAME;
}
@Override
void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE_STMT);
}
}
static LinkedHashMap<String, DbBaseTable> sRCMDbTables = new LinkedHashMap<String, DbBaseTable>();
static {
sRCMDbTables.put(MyTest1Table.getInstance().getName(), MyTest1Table.getInstance());
// sRCMDbTables.put(MyTest2Table.getInstance().getName(), MyTest2Table.getInstance());
}
}
android一些SQL语句的执行得依靠,SQLiteOpenHelper这个类,
我们来建立一个这类的子类:
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) {
<strong> super(context, DataBaseClass.DB_FILE, null, DataBaseClass.DB_VERSION);</strong>
}
public static synchronized DbHelper getInstance(Context context) {
if (dbHelper == null) {
dbHelper = new DbHelper(context);
}
return dbHelper;
}
@Override
public void onCreate(SQLiteDatabase db) {
<strong> Collection<DbBaseTable> tables = DataBaseClass.sRCMDbTables.values();
Iterator<DbBaseTable> 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();
}</strong>
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
private String getTempTableName(String tableName, Collection<String> oldTableNames, Set<String> 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 {
<strong>db_r = super.getReadableDatabase();</strong>
} 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 {
<strong> db_w = super.getWritableDatabase();</strong>
} catch (SQLiteException e) {
//TODO Implement proper error handling
db_w = null;
throw e;
}
}
return db_w;
}
}