Spring Transactional @Transactional中propagation参数的例子，用实际例子来了解各种情况，比看文档更深刻些，需要PostgreSQL Server。
运行AppTests中的doSomthing的测试用例，doSomthing中有7个函数，建议每次运行1个，以便看得更清楚。
如果没有PostgreSQL Server，请先安装一份。可从http://www.postgres.org下载。 创建一个数据库，名为tvseries，并在此数据库内创建1个表，建表语句可参考sq.sql(./sql.sql)文件。
create table person(
id int primary key,
name varchar(50) not null,
birthday timestamp default now()
);mvn test打开一个psql命令行(No.1)：
insert into person (id, name) values(1, 'Tom');
BEGIN TRANSACTION;
SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
SELECT * FROM person WHERE id=1;去另一终端，打开一个psql连接(No.2)，执行
UPDATE person SET name='Mike' WHERE id=1;返回到前面开始事务的终端(No.1)
UPDATE person SET name='Jack' WHERE id=1;会得到错误信息：
ERROR: could not serialize access due to concurrent update
这是遇到了不可重复读，事务运行失败，只能被回滚，即便尝试commit，也不会成功，事务只能被rollback，因为不满足REPEATABLE READ的隔离级别了
首先准备点数据
insert into person (id, name) values(1, 'Tom');
insert into person (id, name) values(2, 'Tom-2');
insert into person (id, name) values(3, 'Tom-3');在(No.1)号psql命令后：
BEGIN TRANSACTION;
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
SELECT * FROM person WHERE id<10;
update person set name='Jack' where id=1;暂停，去另一终端，打开一个psql连接(No.2)，执行
BEGIN TRANSACTION;
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
delete from person where id=3;
SELECT * FROM person WHERE id<5;
COMMIT;返回到前面开始事务的psql命令行(No.1)，commit或者执行其他sql，会得到错误信息：
ERROR: could not serialize access due to read/write dependencies among transactions
DETAIL: Reason code: Canceled on identification as a pivot, during commit attempt.
HINT: The transaction might succeed if retried.
这是遇到了幻读，前面统计到是3条，后面统计到2条，事务运行失败，只能被回滚。如果其中没有update语句，不涉及更新数据会执行成功的。
如果另外一个事务不是设置成SERIALIZABLE，是不会出现这个异常的。postgresql文档中关于serializable有解释说明了这一点
In fact, this isolation level works exactly the same as Repeatable Read except that it monitors for
conditions which could make execution of a concurrent set of serializable transactions behave in a
manner inconsistent with all possible serial (one at a time) executions of those transactions.
只有两个都是SERIABLIZABLE隔离级别的事务才会互相影响。