Spring事物架构抽象及其默认实现

Spring事物基本API：

1、org.springframework.transaction.PlatformTransactionManager是Spring事务抽象架构的核心接口，它的主要作用是为应用程序提供事务界定的统一方式。

public interface PlatformTransactionManager {
    /**
     * 获取事物
     * @param definition
     * @return
     * @throws TransactionException
     */
    TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException;

    
    /**
     * 提交事物
     * @param status
     * @throws TransactionException
     */
    void commit(TransactionStatus status) throws TransactionException;

    
    /**
     * 回滚事物
     * @param status
     * @throws TransactionException
     */
    void rollback(TransactionStatus status) throws TransactionException;

}

2、org.springframework.transaction.TransactionDefinition定义事务的隔离级别、传播行为、超时信息、只读信息

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} 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}, a
     * Hibernate {@code Session}, 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} with care! In particular, do
     * not rely on {@code PROPAGATION_REQUIRED} or {@code PROPAGATION_REQUIRES_NEW}
     * <i>within</i> a {@code PROPAGATION_SUPPORTS} 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}
     * 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} to be
     * made available it to it (which is server-specific in standard Java EE).
     * <p>A {@code PROPAGATION_REQUIRES_NEW} 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} to be
     * made available it to it (which is server-specific in standard Java EE).
     * <p>Note that transaction synchronization is <i>not</i> available within a
     * {@code PROPAGATION_NOT_SUPPORTED} 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} 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;


    /**
     * 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} condition, a second transaction inserts a row
     * that satisfies that {@code WHERE} 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} 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} 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}.
     * <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} 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}.
     * <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} (by default).
     * @return the name of this transaction
     * @see org.springframework.transaction.interceptor.TransactionAspectSupport
     * @see org.springframework.transaction.support.TransactionSynchronizationManager#getCurrentTransactionName()
     */
    String getName();

}

3、org.springframework.transaction.TransactionStatus表示当前事物状态

public interface TransactionStatus extends SavepointManager, Flushable {

    /**
     * Return whether the present transaction is new (else participating
     * in an existing transaction, or potentially not running in an
     * actual transaction in the first place).
     */
    boolean isNewTransaction();

    /**
     * Return whether this transaction internally carries a savepoint,
     * that is, has been created as nested transaction based on a savepoint.
     * <p>This method is mainly here for diagnostic purposes, alongside
     * {@link #isNewTransaction()}. For programmatic handling of custom
     * savepoints, use SavepointManager's operations.
     * @see #isNewTransaction()
     * @see #createSavepoint
     * @see #rollbackToSavepoint(Object)
     * @see #releaseSavepoint(Object)
     */
    boolean hasSavepoint();

    /**
     * Set the transaction rollback-only. This instructs the transaction manager
     * that the only possible outcome of the transaction may be a rollback, as
     * alternative to throwing an exception which would in turn trigger a rollback.
     * <p>This is mainly intended for transactions managed by
     * {@link org.springframework.transaction.support.TransactionTemplate} or
     * {@link org.springframework.transaction.interceptor.TransactionInterceptor},
     * where the actual commit/rollback decision is made by the container.
     * @see org.springframework.transaction.support.TransactionCallback#doInTransaction
     * @see org.springframework.transaction.interceptor.TransactionAttribute#rollbackOn
     */
    void setRollbackOnly();

    /**
     * Return whether the transaction has been marked as rollback-only
     * (either by the application or by the transaction infrastructure).
     */
    boolean isRollbackOnly();

    /**
     * Flush the underlying session to the datastore, if applicable:
     * for example, all affected Hibernate/JPA sessions.
     * <p>This is effectively just a hint and may be a no-op if the underlying
     * transaction manager does not have a flush concept. A flush signal may
     * get applied to the primary resource or to transaction synchronizations,
     * depending on the underlying resource.
     */
    @Override
    void flush();

    /**
     * Return whether this transaction is completed, that is,
     * whether it has already been committed or rolled back.
     * @see PlatformTransactionManager#commit
     * @see PlatformTransactionManager#rollback
     */
    boolean isCompleted();

}