Android数据库事务

Question

我创建了一个数据库.我想做交易.SaveCustomer()包含多个语句,以便Customer, CustomerControl, Profile, Payment在那时将记录插入表中.

当用户调用 SaveCustomer()方法时,该数据将转到这4个表.所以我该如何进行交易？如果一个表插入失败,则需要回滚所有内容.例如,当第3个表插入记录时出现错误,那么还需要回滚前两个表的插入记录.

看我的代码:

public void saveCustomer(){
    DBAdapter dbAdapter = DBAdapter.getDBAdapterInstance(RetailerOrderKeyActivity.this);
    dbAdapter.openDataBase();
    ContentValues initialValues = new ContentValues();
    initialValues.put("CustomerName",customer.getName());
    initialValues.put("Address",customer.getAddress());
    initialValues.put("CustomerPID",strPID);
    initialValues.put("Date",strDateOnly);
    long n = dbAdapter.insertRecordsInDB("Customer", null, initialValues);

}

同样其他声明也在那里.

DBAdpter代码是:

public long insertRecordsInDB(String tableName, String nullColumnHack,ContentValues initialValues) {
    long n =-1;
    try {
        myDataBase.beginTransaction();
        n = myDataBase.insert(tableName, nullColumnHack, initialValues);

        myDataBase.endTransaction();
        myDataBase.setTransactionSuccessful();
    } catch (Exception e) {
        // how to do the rollback 
        e.printStackTrace();
    }

    return n;
}

这是完整的代码:

public class DBAdapter extends SQLiteOpenHelper {

    private static String DB_PATH = "/data/data/com.my.controller/databases/";
    private static final String DB_NAME = "customer";
    private SQLiteDatabase myDataBase;
    private final Context myContext;
    private static DBAdapter mDBConnection;


    private DBAdapter(Context context) {
        super(context, DB_NAME, null, 1);
        this.myContext = context;
        DB_PATH = "/data/data/"
                + context.getApplicationContext().getPackageName()
                + "/databases/";
        // The Android's default system path of your application database is
        // "/data/data/mypackagename/databases/"
    }


    public static synchronized DBAdapter getDBAdapterInstance(Context context) {
        if (mDBConnection == null) {
            mDBConnection = new DBAdapter(context);
        }
        return mDBConnection;
    }


    public void createDataBase() throws IOException {
        boolean dbExist = checkDataBase();
        if (dbExist) {
            // do nothing - database already exist
        } else {
            // By calling following method 
            // 1) an empty database will be created into the default system path of your application 
            // 2) than we overwrite that database with our database.
            this.getReadableDatabase();
            try {
                copyDataBase();
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }
    }


    private boolean checkDataBase() {
        SQLiteDatabase checkDB = null;

        try {
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null,SQLiteDatabase.OPEN_READONLY);

        } catch (SQLiteException e) {
            // database does't exist yet.
        }
        if (checkDB != null) {
            checkDB.close();
        }
        return checkDB != null ? true : false;
    }


    private void copyDataBase() throws IOException {
        InputStream myInput = myContext.getAssets().open(DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        OutputStream myOutput = new FileOutputStream(outFileName);  
    byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }
            // Close the streams
        myOutput.flush();
        myOutput.close();
        myInput.close();
    }

    /**
     * Open the database
     * @throws SQLException
     */
    public void openDataBase() throws SQLException {
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);      
    }


    @Override
    public synchronized void close() {
        if (myDataBase != null)
            myDataBase.close();
        super.close();
    }

    /**
     * Call on creating data base for example for creating tables at run time
     */
    @Override
    public void onCreate(SQLiteDatabase db) {
    }


    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("ALTER TABLE WMPalmUploadControl ADD Testing int");

    }

    public void upgradeDb(){
        onUpgrade(myDataBase, 1, 2);
    }

    public Cursor selectRecordsFromDB(String tableName, String[] tableColumns,
            String whereClase, String whereArgs[], String groupBy,
            String having, String orderBy) {
        return myDataBase.query(tableName, tableColumns, whereClase, whereArgs,
                groupBy, having, orderBy);
    }


    public ArrayList<ArrayList<String>> selectRecordsFromDBList(String tableName, String[] tableColumns,
            String whereClase, String whereArgs[], String groupBy,
            String having, String orderBy) {        

        ArrayList<ArrayList<String>> retList = new ArrayList<ArrayList<String>>();
          ArrayList<String> list = new ArrayList<String>();
          Cursor cursor = myDataBase.query(tableName, tableColumns, whereClase, whereArgs,
                    groupBy, having, orderBy);        
          if (cursor.moveToFirst()) {
             do {
                 list = new ArrayList<String>();
                 for(int i=0; i<cursor.getColumnCount(); i++){                   
                     list.add( cursor.getString(i) );
                 }   
                 retList.add(list);
             } while (cursor.moveToNext());
          }
          if (cursor != null && !cursor.isClosed()) {
             cursor.close();
          }
          return retList;

    }   


    public long insertRecordsInDB(String tableName, String nullColumnHack,ContentValues initialValues) {
        long n =-1;
        try {
            myDataBase.beginTransaction();
            n = myDataBase.insert(tableName, nullColumnHack, initialValues);

            myDataBase.endTransaction();
            myDataBase.setTransactionSuccessful();
        } catch (Exception e) {
            // how to do the rollback 
            e.printStackTrace();
        }

        return n;
    }


    public boolean updateRecordInDB(String tableName,
            ContentValues initialValues, String whereClause, String whereArgs[]) {
        return myDataBase.update(tableName, initialValues, whereClause,
                whereArgs) > 0;             
    }

    public int updateRecordsInDB(String tableName,
            ContentValues initialValues, String whereClause, String whereArgs[]) {
        return myDataBase.update(tableName, initialValues, whereClause, whereArgs);     
    }


    public int deleteRecordInDB(String tableName, String whereClause,
            String[] whereArgs) {
        return myDataBase.delete(tableName, whereClause, whereArgs);
    }


    public Cursor selectRecordsFromDB(String query, String[] selectionArgs) {
        return myDataBase.rawQuery(query, selectionArgs);       
    }


    public ArrayList<ArrayList<String>> selectRecordsFromDBList(String query, String[] selectionArgs) {       
          ArrayList<ArrayList<String>> retList = new ArrayList<ArrayList<String>>();
          ArrayList<String> list = new ArrayList<String>();
          Cursor cursor = myDataBase.rawQuery(query, selectionArgs);            
          if (cursor.moveToFirst()) {
             do {
                 list = new ArrayList<String>();
                 for(int i=0; i<cursor.getColumnCount(); i++){                   
                     list.add( cursor.getString(i) );
                 }   
                 retList.add(list);
             } while (cursor.moveToNext());
          }
          if (cursor != null && !cursor.isClosed()) {
             cursor.close();
          }
          return retList;
       }

}

HTC Desire中的数据库锁定问题.

如果插入表数据时出现任何问题,我想回滚.

请帮我

谢谢.

我看了同样的相关问题:

Answer 1

其实你做错了.如果要将多个记录插入到数据库中,或者如果在其中一个数据库表中插入数据时出现问题,则必须从其他表回滚数据,则必须设置begin transaction.

例如

你有两张桌子

1. 一个
2. 乙

现在,您希望在这两个表中插入数据,但如果在表中插入数据时出现任何错误,则必须回滚事务.

现在您已成功在表A中插入数据,现在您正尝试在表B中插入数据.现在,如果在表B中插入数据时出现错误,则必须从表A中删除相关数据,这意味着您必须回滚交易.

如何在Android中使用数据库事务

1. 如果要启动事务,则有一种方法 beginTransaction()
2. 如果要提交事务,则有一种方法setTransactionSuccessful()可以提交数据库中的值
3. 如果您已启动事务,则需要关闭事务,以便有一个方法endTransaction()可以结束数据库事务

现在有两个要点

1. 如果你想设置的交易获得成功,你需要写setTransactionSuccessful(),然后endTransaction()经过beginTransaction()
2. 如果要回滚事务,则需要endTransaction()不提交事务setTransactionSuccessful().

您可以从此处获取有关SQLite数据库事务的详细信息

在你的情况下

你可以saveCustomer()在try和catch块中调用你的函数

db.beginTransaction();
try {
    saveCustomer();
    db.setTransactionSuccessful();
} catch {
    //Error in between database transaction 
} finally {
    db.endTransaction();
}

Answer 2

你应该加入endTransaction你的finally,而不是你的尝试块

 finally {
     myDataBase.endTransaction();
   }

如果任何事务结束而没有标记为干净(通过调用setTransactionSuccessful),则将回滚更改.否则他们将被承诺.

Answer 3

使用事务插入记录,这非常快

String sql = "INSERT INTO table (col1, col2) VALUES (?, ?)";
db.beginTransaction();

SQLiteStatement stmt = db.compileStatement(sql);
for (int i = 0; i < values.size(); i++) {
    stmt.bindString(1, values.get(i).col1);
    stmt.bindString(2, values.get(i).col2);
    stmt.execute();
    stmt.clearBindings();
}

db.setTransactionSuccessful();
db.endTransaction();