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Android中数据库事务

事务概念

             在事务中包含的sql,要么同时执行成功 要么同时执行失败, 不能出现 部分成功部分失败的情况 典型案例 银行转账

 相关api

1. db.beginTransaction();//开启事务
2. try {
3. ...
4. db.setTransactionSuccessful();//如果所有SQL都执行完毕则标记成功
5. } finally {
6. db.endTransaction();//如果有成功标记则关闭事务,没有成功标记回滚数据
7. }

 具体代码

MyOpenHelper类

1. public class MyOpenHelper extends SQLiteOpenHelper {
2. public MyOpenHelper(Context context) {
3. super(context, "Account.db", null, 1);
4. }
5. @Override
6. public void onCreate(SQLiteDatabase db) {
7. db.execSQL("create table info (_id integer primary key autoincrement,name varchar(20),phone varchar(20),money varchar(20))");
8. db.execSQL("insert into info ('name','phone','money') values ('张三','138888','2000')");
9. db.execSQL("insert into info ('name','phone','money') values ('李四','139999','5000')");
10. }
11. @Override
12. public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
13. }
14. }

MainActivity类

1. public class MainActivity extends Activity {
2. private MyOpenHelper openHelper;
3. @Override
4. protected void onCreate(Bundle savedInstanceState) {
5. super.onCreate(savedInstanceState);
6. setContentView(R.layout.activity_main);
7. //获取MyOpenHelper 用它可以获取SQLiteDatabase
8. openHelper = new MyOpenHelper(this);
9. }
10. public void transaction(View v){
11. SQLiteDatabase database = openHelper.getWritableDatabase();
12. //开启事务
13. database.beginTransaction();
14. try {
15. database.execSQL("update info set money= money-200 where name=?",new String[]{"张三"});
16. //int i = 100/0;
17. database.execSQL("update info set money= money+200 where name=?",new String[]{"李四"});
18. //事务所有的sql执行成功之后 调用 setTransactionSuccessful 会加上一个标记说明事务成功执行了
19. database.setTransactionSuccessful();
20. } catch (Exception e) {
21. Toast.makeText(getApplicationContext(), "服务器忙,请稍后再试", 0).show();
22. }finally {
23. //事务结束 会检查标记 如果没有成功标记则回滚 如果有成功标记则提交生效
24. database.endTransaction();
25. }
26. }
27. }