事务
通过事务，可以控制 JDBC 批处理（batch size，flushing），控制事务日志开关，打开、关闭储存与删除的级联操作等工作
隐式
隐式创建事务
如果当前没有申明事务，任然可以创建，保存或删除一个 bena。在这种情况下，Ebean 会隐式的创建一个事务并提交（或者在失败时回滚）。
// execute a query without an existing transaction...
// ... a "implicit" transaction will be created
// ... and be commited (or rolled back) for you
List<User> users =
Ebean.find(User.class)
.join("customer")
.where().eq("state", UserState.ACTIVE)
.findList();
// execute a save without an existing transaction...
// ... will create an implicit transaction
// ... and be commited (or rolled back) for you
Ebean.save(user);
下面的 SL4J 日志显示隐式事务的查询创建任务。
16:38:26.362 [main] DEBUG c.a.e.server.lib.thread.ThreadPool - ThreadPool grow created [Ebean-h2.0] size[0]
16:38:26.369 [main] TRACE org.avaje.ebean.TXN - txn[1002] Begin
16:38:26.548 [main] INFO org.avaje.ebean.TXN - txn[1002] Commit
16:38:26.551 [main] TRACE org.avaje.ebean.TXN - txn[1003] Begin
16:38:26.554 [main] TRACE org.avaje.ebean.SQL - txn[1003] delete from or_order_ship
16:38:26.555 [main] DEBUG org.avaje.ebean.SUM - txn[1003] Delete table[or_order_ship] rows[0] bind[null]
16:38:26.556 [main] TRACE org.avaje.ebean.SQL - txn[1003] delete from o_order_detail
16:38:26.557 [main] DEBUG org.avaje.ebean.SUM - txn[1003] Delete table[o_order_detail] rows[0] bind[null]
16:38:26.557 [main] TRACE org.avaje.ebean.SQL - txn[1003] delete from o_order
16:38:26.557 [main] DEBUG org.avaje.ebean.SUM - txn[1003] Delete table[o_order] rows[0] bind[null]
16:38:26.557 [main] TRACE org.avaje.ebean.SQL - txn[1003] delete from contact
16:38:26.557 [main] DEBUG org.avaje.ebean.SUM - txn[1003] Delete table[contact] rows[0] bind[null]
16:38:26.557 [main] TRACE org.avaje.ebean.SQL - txn[1003] delete from o_customer
16:38:26.557 [main] DEBUG org.avaje.ebean.SUM - txn[1003] Delete table[o_customer] rows[0] bind[null]
16:38:26.557 [main] TRACE org.avaje.ebean.SQL - txn[1003] delete from o_address
16:38:26.558 [main] DEBUG org.avaje.ebean.SUM - txn[1003] Delete table[o_address] rows[0] bind[null]
16:38:26.563 [main] TRACE org.avaje.ebean.SQL - txn[1003] delete from o_country
16:38:26.563 [main] DEBUG org.avaje.ebean.SUM - txn[1003] DeleteSql table[o_country] rows[0] bind[null]
16:38:26.563 [main] TRACE org.avaje.ebean.SQL - txn[1003] delete from o_product
16:38:26.564 [main] DEBUG org.avaje.ebean.SUM - txn[1003] DeleteSql table[o_product] rows[0] bind[null]
16:38:26.567 [main] TRACE org.avaje.ebean.SQL - txn[1003] insert into o_country (code, name) values (?,?); --bind(NZ,New Zealand,)
16:38:26.568 [main] DEBUG org.avaje.ebean.SUM - txn[1003] Inserted [Country] [NZ]
16:38:26.568 [main] TRACE org.avaje.ebean.SQL - txn[1003] insert into o_country (code, name) values (?,?); --bind(AU,Australia,)
16:38:26.568 [main] DEBUG org.avaje.ebean.SUM - txn[1003] Inserted [Country] [AU]
16:38:26.570 [main] TRACE org.avaje.ebean.SQL - txn[1003] insert into o_product (id, sku, name, cretime, updtime) values (?,?,?,?,?); --bind
编程
在 try finally 块中使用 begin，commit等
一个声明事务的传统方式，通过 try finally 块
ebeanServer.beginTransaction();
try {
// fetch some stuff...
Customer customer = ebeanServer.find(Customer.class, id);
...
// save or delete stuff...
ebeanServer.save(customer);
...
// commit the transaction
ebeanServer.commitTransaction();
finally {
// rollback the transaction if it was not committed
ebeanServer.endTransaction();
}
在事务中控制行为
你可以使用事务明确控制行为.
Transaction transaction = ebeanServer.beginTransaction();
try {
// turn of cascade persist
transaction.setCascadePersist(false);
// control the jdbc batch mode and size
// transaction.setBatchMode(true); // equivalent to transaction.setBatch(PersistBatch.ALL);
// transaction.setBatchMode(false); // equivalent to transaction.setBatch(PersistBatch.NONE);
transaction.setBatch(PersistBatch.ALL); // PersistBatch: NONE, INSERT, ALL
transaction.setCascadeBatch(PersistBatch.INSERT); // PersistBatch: NONE, INSERT, ALL
transaction.setBatchSize(30);
// for a large batch insert if you want to skip
// getting the generated keys
transaction.setBatchGetGeneratedKeys(false);
// for batch processing via raw SQL you can inform
// Ebean what tables were modified so that it can
// clear the appropriate L2 caches
String tableName = "o_customer";
boolean inserts = true;
boolean upates = true;
boolean deletes = false;
transaction.addModification(tableName, inserts, updates, deletes);
...
} finally {
transaction.end();
}
@Transactional
必须使用 ENHANCEMENT 才能使用 @Transactional生效，也就是说你必须通过 IDE，Ant 任务或者javaagent 增强 class。更多细节参考usergide 的enhancement。
Ebean 可以为 pojo 类添加事务支持。你可以将@Transactional注解置于一个方法或类上面，Ebean 会加入事务逻辑支持(开始事务，提交，回滚，暂停和恢复交易等)。
...
// any old pojo
public class MyService {
@Transactional
public void runFirst() throws IOException {
// run in a Transaction (REQUIRED is the default)
// find a customer
Customer customer = Ebean.find(Customer.class, 1);
// call another "transactional" method
runInTrans();
}
@Transactional(type=TxType.REQUIRES_NEW)
public void runInTrans() throws IOException {
// run in its own NEW transaction
// ... suspend an existing transaction if required
// ... and resume it when this method ends
// find new orders
List<Order> orders = Ebean.find(Order.class)
.where().eq("status",OrderStatus.NEW)
.findList();
...
将@Transactional置于方法上，Ebean会增强类添加事务管理。
标准事务范围
支持标准的REQUIRED (默认), REQUIRES_NEW, MANDATORY, SUPPORTS, NOT_SUPPORTS, NEVER规则。这些完全匹配 EJB 的 TransactionAttributeTypes。
嵌套事务
事务可以被嵌套，就像上述的例子一样，runFirst()中调用了runInTrans()。
隔离级别并支持具体异常
@Transactional（比如Spring）支持隔离级别和异常的显式处理(回滚或不特定类型的异常)。请参考用户指南获取更详细的解释。
接口
你可以将@Transactional置于接口上，那么其实现类将会被 Ebean 添加事务管理。
TxRunnable / TxCallable
TxRunnable 和 TxCallable 几乎等同于@Transactional的纲领性。 如果你愿意，你可以将 TxRunnable 和 TxCallable 与@Transactional混合使用，他们将正确地工作。
public void myMethod() {
...
System.out.println(" Some code in myMethod...");
// run in Transactional scope...
Ebean.execute(new TxRunnable() {
public void run() {
// code running in "REQUIRED" transactional scope
// ... as "REQUIRED" is the default TxType
System.out.println(Ebean.currentTransaction());
// find stuff...
User user = Ebean.find(User.class, 1);
...
// save and delete stuff...
Ebean.save(user);
Ebean.delete(order);
...
}
});
System.out.println(" more code in myMethod...");
}
一般来说，你会像上面一样使用 TxRunnable创建一个匿名内部类。 run()方法内部的代码将会有一个 Ebean 通过事务传递的事务作用域(就像@Transactional)。
// programmatic control over the scope such as
// ... isolation level
// ... and to rollback or not for specific exceptions
TxScope txScope = TxScope
.requiresNew()
.setIsolation(TxIsolation.SERIALIZABLE)
.setNoRollbackFor(IOException.class);
Ebean.execute(txScope, new TxRunnable() {
public void run() {
...
}
Spring
(under construction)
JTA
(under construction)