/**
* Interface that defines Spring-compliant transaction properties.
* Based on the propagation behavior definitions analogous to EJB CMT attributes.
*
* <p>Note that isolation level and timeout settings will not get applied unless
* an actual new transaction gets started. As only {@link #PROPAGATION_REQUIRED},
* {@link #PROPAGATION_REQUIRES_NEW} and {@link #PROPAGATION_NESTED} can cause
* that, it usually doesn't make sense to specify those settings in other cases.
* Furthermore, be aware that not all transaction managers will support those
* advanced features and thus might throw corresponding exceptions when given
* non-default values.
*
* <p>The {@link #isReadOnly() read-only flag} applies to any transaction context,
* whether backed by an actual resource transaction or operating non-transactionally
* at the resource level. In the latter case, the flag will only apply to managed
* resources within the application, such as a Hibernate <code>Session</code>.
*
* @author Juergen Hoeller
* @since 08.05.2003
* @see PlatformTransactionManager#getTransaction(TransactionDefinition)
* @see org.springframework.transaction.support.DefaultTransactionDefinition
* @see org.springframework.transaction.interceptor.TransactionAttribute
*/
public interface TransactionDefinition {
/**
* Support a current transaction; create a new one if none exists.
* Analogous to the EJB transaction attribute of the same name.
* <p>This is typically the default setting of a transaction definition,
* and typically defines a transaction synchronization scope.
*/
int PROPAGATION_REQUIRED = 0;
/**
* Support a current transaction; execute non-transactionally if none exists.
* Analogous to the EJB transaction attribute of the same name.
* <p><b>NOTE:</b> For transaction managers with transaction synchronization,
* <code>PROPAGATION_SUPPORTS</code> is slightly different from no transaction
* at all, as it defines a transaction scope that synchronization might apply to.
* As a consequence, the same resources (a JDBC <code>Connection</code>, a
* Hibernate <code>Session</code>, etc) will be shared for the entire specified
* scope. Note that the exact behavior depends on the actual synchronization
* configuration of the transaction manager!
* <p>In general, use <code>PROPAGATION_SUPPORTS</code> with care! In particular, do
* not rely on <code>PROPAGATION_REQUIRED</code> or <code>PROPAGATION_REQUIRES_NEW</code>
* <i>within</i> a <code>PROPAGATION_SUPPORTS</code> scope (which may lead to
* synchronization conflicts at runtime). If such nesting is unavoidable, make sure
* to configure your transaction manager appropriately (typically switching to
* "synchronization on actual transaction").
* @see org.springframework.transaction.support.AbstractPlatformTransactionManager#setTransactionSynchronization
* @see org.springframework.transaction.support.AbstractPlatformTransactionManager#SYNCHRONIZATION_ON_ACTUAL_TRANSACTION
*/
int PROPAGATION_SUPPORTS = 1;
/**
* Support a current transaction; throw an exception if no current transaction
* exists. Analogous to the EJB transaction attribute of the same name.
* <p>Note that transaction synchronization within a <code>PROPAGATION_MANDATORY</code>
* scope will always be driven by the surrounding transaction.
*/
int PROPAGATION_MANDATORY = 2;
/**
* Create a new transaction, suspending the current transaction if one exists.
* Analogous to the EJB transaction attribute of the same name.
* <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box
* on all transaction managers. This in particular applies to
* {@link org.springframework.transaction.jta.JtaTransactionManager},
* which requires the <code>javax.transaction.TransactionManager</code>
* to be made available it to it (which is server-specific in standard J2EE).
* <p>A <code>PROPAGATION_REQUIRES_NEW</code> scope always defines its own
* transaction synchronizations. Existing synchronizations will be suspended
* and resumed appropriately.
* @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
*/
int PROPAGATION_REQUIRES_NEW = 3;
/**
* Do not support a current transaction; rather always execute non-transactionally.
* Analogous to the EJB transaction attribute of the same name.
* <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box
* on all transaction managers. This in particular applies to
* {@link org.springframework.transaction.jta.JtaTransactionManager},
* which requires the <code>javax.transaction.TransactionManager</code>
* to be made available it to it (which is server-specific in standard J2EE).
* <p>Note that transaction synchronization is <i>not</i> available within a
* <code>PROPAGATION_NOT_SUPPORTED</code> scope. Existing synchronizations
* will be suspended and resumed appropriately.
* @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
*/
int PROPAGATION_NOT_SUPPORTED = 4;
/**
* Do not support a current transaction; throw an exception if a current transaction
* exists. Analogous to the EJB transaction attribute of the same name.
* <p>Note that transaction synchronization is <i>not</i> available within a
* <code>PROPAGATION_NEVER</code> scope.
*/
int PROPAGATION_NEVER = 5;
/**
* Execute within a nested transaction if a current transaction exists,
* behave like {@link #PROPAGATION_REQUIRED} else. There is no analogous
* feature in EJB.
* <p><b>NOTE:</b> Actual creation of a nested transaction will only work on
* specific transaction managers. Out of the box, this only applies to the JDBC
* {@link org.springframework.jdbc.datasource.DataSourceTransactionManager}
* when working on a JDBC 3.0 driver. Some JTA providers might support
* nested transactions as well.
* @see org.springframework.jdbc.datasource.DataSourceTransactionManager
*/
int PROPAGATION_NESTED = 6;//支持当前事务，新增Savepoint点，与当前事务同步提交或回滚。它只对DataSourceTransactionManager有效。
/**
* Use the default isolation level of the underlying datastore.
* All other levels correspond to the JDBC isolation levels.
* @see java.sql.Connection
*/
int ISOLATION_DEFAULT = -1;
/**
* Indicates that dirty reads, non-repeatable reads and phantom reads
* can occur.
* <p>This level allows a row changed by one transaction to be read by another
* transaction before any changes in that row have been committed (a "dirty read").
* If any of the changes are rolled back, the second transaction will have
* retrieved an invalid row.
* @see java.sql.Connection#TRANSACTION_READ_UNCOMMITTED
*/
int ISOLATION_READ_UNCOMMITTED = Connection.TRANSACTION_READ_UNCOMMITTED;
/**
* Indicates that dirty reads are prevented; non-repeatable reads and
* phantom reads can occur.
* <p>This level only prohibits a transaction from reading a row
* with uncommitted changes in it.
* @see java.sql.Connection#TRANSACTION_READ_COMMITTED
*/
int ISOLATION_READ_COMMITTED = Connection.TRANSACTION_READ_COMMITTED;
/**
* Indicates that dirty reads and non-repeatable reads are prevented;
* phantom reads can occur.
* <p>This level prohibits a transaction from reading a row with uncommitted changes
* in it, and it also prohibits the situation where one transaction reads a row,
* a second transaction alters the row, and the first transaction re-reads the row,
* getting different values the second time (a "non-repeatable read").
* @see java.sql.Connection#TRANSACTION_REPEATABLE_READ
*/
int ISOLATION_REPEATABLE_READ = Connection.TRANSACTION_REPEATABLE_READ;
/**
* Indicates that dirty reads, non-repeatable reads and phantom reads
* are prevented.
* <p>This level includes the prohibitions in {@link #ISOLATION_REPEATABLE_READ}
* and further prohibits the situation where one transaction reads all rows that
* satisfy a <code>WHERE</code> condition, a second transaction inserts a row
* that satisfies that <code>WHERE</code> condition, and the first transaction
* re-reads for the same condition, retrieving the additional "phantom" row
* in the second read.
* @see java.sql.Connection#TRANSACTION_SERIALIZABLE
*/
int ISOLATION_SERIALIZABLE = Connection.TRANSACTION_SERIALIZABLE;
/**
* Use the default timeout of the underlying transaction system,
* or none if timeouts are not supported.
*/
int TIMEOUT_DEFAULT = -1;
/**
* Return the propagation behavior.
* <p>Must return one of the <code>PROPAGATION_XXX</code> constants
* defined on {@link TransactionDefinition this interface}.
* @return the propagation behavior
* @see #PROPAGATION_REQUIRED
* @see org.springframework.transaction.support.TransactionSynchronizationManager#isActualTransactionActive()
*/
int getPropagationBehavior();
/**
* Return the isolation level.
* <p>Must return one of the <code>ISOLATION_XXX</code> constants
* defined on {@link TransactionDefinition this interface}.
* <p>Only makes sense in combination with {@link #PROPAGATION_REQUIRED}
* or {@link #PROPAGATION_REQUIRES_NEW}.
* <p>Note that a transaction manager that does not support custom isolation levels
* will throw an exception when given any other level than {@link #ISOLATION_DEFAULT}.
* @return the isolation level
*/
int getIsolationLevel();
/**
* Return the transaction timeout.
* <p>Must return a number of seconds, or {@link #TIMEOUT_DEFAULT}.
* <p>Only makes sense in combination with {@link #PROPAGATION_REQUIRED}
* or {@link #PROPAGATION_REQUIRES_NEW}.
* <p>Note that a transaction manager that does not support timeouts will throw
* an exception when given any other timeout than {@link #TIMEOUT_DEFAULT}.
* @return the transaction timeout
*/
int getTimeout();
/**
* Return whether to optimize as a read-only transaction.
* <p>The read-only flag applies to any transaction context, whether
* backed by an actual resource transaction
* ({@link #PROPAGATION_REQUIRED}/{@link #PROPAGATION_REQUIRES_NEW}) or
* operating non-transactionally at the resource level
* ({@link #PROPAGATION_SUPPORTS}). In the latter case, the flag will
* only apply to managed resources within the application, such as a
* Hibernate <code>Session</code>.
<< * <p>This just serves as a hint for the actual transaction subsystem;
* it will <i>not necessarily</i> cause failure of write access attempts.
* A transaction manager which cannot interpret the read-only hint will
* <i>not</i> throw an exception when asked for a read-only transaction.
* @return <code>true</code> if the transaction is to be optimized as read-only
* @see org.springframework.transaction.support.TransactionSynchronization#beforeCommit(boolean)
* @see org.springframework.transaction.support.TransactionSynchronizationManager#isCurrentTransactionReadOnly()
*/
boolean isReadOnly();
/**
* Return the name of this transaction. Can be <code>null</code>.
* <p>This will be used as the transaction name to be shown in a
* transaction monitor, if applicable (for example, WebLogic's).
* <p>In case of Spring's declarative transactions, the exposed name will be
* the <code>fully-qualified class name + "." + method name</code> (by default).
* @return the name of this transaction
* @see org.springframework.transaction.interceptor.TransactionAspectSupport
* @see org.springframework.transaction.support.TransactionSynchronizationManager#getCurrentTransactionName()
*/
String getName();
}
