实例教程七：在SQLite中使用事务

系统文件管理器
http://www.eoeandroid.com/thread-128567-1-1.html

android 实现区域截图
http://www.eoeandroid.com/thread-149439-1-1.html

影院选坐 写着玩的
http://www.eoeandroid.com/thread-151980-1-1.html

继上章
1.在数据库表person添加字段amount
2.在Person类中添加相应的amount
3.在PersonService添加payment()方法

public void payment(){

 

                SQLiteDatabase db = dbOpenHelper.getWritableDatabase();

 

                db.beginTransaction(); //开户事务

 

                try{

 

                db.execSQL("update person set amount=amount-10 where personId=1");

 

                db.execSQL("update person set amount=amount-10 where personId=2");

 

                db.setTransactionSuccessful(); //设置事务的标志为True

 

                }finally{

 

                        //为何要加try...catch

 

                        //因为添加了db.setTransactionSuccessful()，若execSQL中出现问题

 

                        //则不会执行db.endTransaction()

 

                        db.endTransaction(); //结束事务，有2种情况：commit, rollback

 

                }                

                //事务的提交或回滚是由事务的标志决定的

 

                //如果事务的标志为True,事务就会提交

 

                //否则事务就会回滚，默认情况下事务的标志为false

 

        }

4.初始化amount值，便于调用

public void testUpdateAmount() throws Exception{

 

                PersonService service = new PersonService(this.getContext());

 

                Person person1 = service.find(1);

 

                Person person2 = service.find(2);

 

                person1.setAmount(100);

 

                person2.setAmount(200);

 

                service.update(person1);

 

                service.update(person2);

 

        }

5.在单元测试类PersonServiceTest中添加测试方法testPayment()

public void testPayment() throws Exception{

 

                PersonService service = new PersonService(this.getContext());

 

                service.payment();

 

        }