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接口 JavaMigration

public interface JavaMigration

Interface to be implemented by Java-based Migrations.

Java-based migrations are a great fit for all changes that can not easily be expressed using SQL.

These would typically be things like

• BLOB & CLOB changes
• Advanced bulk data changes (Recalculations, advanced format changes, ...)

Migration classes implementing this interface will be automatically discovered when placed in a location on the classpath.

Most users will be better served by subclassing subclass BaseJavaMigration instead of implementing this interface directly, as BaseJavaMigration encourages the use of Flyway's default naming convention and comes with sensible default implementations of all methods (except migrate of course) while at the same time also providing better isolation against future additions to this interface.

方法概要

限定符和类型	方法和说明
boolean	canExecuteInTransaction() Whether the execution should take place inside a transaction.
Integer	getChecksum() Computes the checksum of the migration.
String	getDescription()
MigrationVersion	getVersion()
boolean	isUndo() Whether this is an undo migration for a previously applied versioned migration.
void	migrate(Context context) Executes this migration.

方法详细资料

getVersion

MigrationVersion getVersion()

返回:

The version of the schema after the migration is complete. null for repeatable migrations.

getDescription

String getDescription()

返回:

The description of this migration for the migration history. Never null.

getChecksum

Integer getChecksum()

Computes the checksum of the migration.

返回:

The checksum of the migration.

isUndo

boolean isUndo()

Whether this is an undo migration for a previously applied versioned migration.

返回:

true if it is, false if not. Always false for repeatable migrations.

canExecuteInTransaction

boolean canExecuteInTransaction()

Whether the execution should take place inside a transaction. Almost all implementation should return true. This however makes it possible to execute certain migrations outside a transaction. This is useful for databases like PostgreSQL and SQL Server where certain statement can only execute outside a transaction.

返回:

true if a transaction should be used (highly recommended), or false if not.

migrate

void migrate(Context context)
      throws Exception

Executes this migration. The execution will automatically take place within a transaction, when the underlying database supports it and the canExecuteInTransaction returns true.

参数:

context - The context relevant for this migration, containing things like the JDBC connection to use and the current Flyway configuration.

抛出:

Exception - when the migration failed.