这是因为在spring-boot-autoconfigure项目下有一个FlywayAutoConfiguration类。代码如下：
package org.springframework.boot.autoconfigure.flyway;
......
/**
* {@link EnableAutoConfiguration Auto-configuration} for Flyway database migrations.
*
* @author Dave Syer
* @author Phillip Webb
* @author Vedran Pavic
* @author Stephane Nicoll
* @author Jacques-Etienne Beaudet
* @author Eddú Meléndez
* @author Dominic Gunn
* @since 1.1.0
*/
@SuppressWarnings("deprecation")
@Configuration
@ConditionalOnClass(Flyway.class)
@ConditionalOnBean(DataSource.class)
@ConditionalOnProperty(prefix = "spring.flyway", name = "enabled", matchIfMissing = true)
@AutoConfigureAfter({ DataSourceAutoConfiguration.class,
JdbcTemplateAutoConfiguration.class, HibernateJpaAutoConfiguration.class })
public class FlywayAutoConfiguration {
@Bean
@ConfigurationPropertiesBinding
public StringOrNumberToMigrationVersionConverter stringOrNumberMigrationVersionConverter() {
return new StringOrNumberToMigrationVersionConverter();
}
@Bean
public FlywaySchemaManagementProvider flywayDefaultDdlModeProvider(
ObjectProvider<Flyway> flyways) {
return new FlywaySchemaManagementProvider(flyways);
}
@Configuration
@ConditionalOnMissingBean(Flyway.class)
@EnableConfigurationProperties({ DataSourceProperties.class, FlywayProperties.class })
public static class FlywayConfiguration {
private final FlywayProperties properties;
private final DataSourceProperties dataSourceProperties;
private final ResourceLoader resourceLoader;
private final DataSource dataSource;
private final DataSource flywayDataSource;
private final FlywayMigrationStrategy migrationStrategy;
private final List<FlywayConfigurationCustomizer> configurationCustomizers;
private final List<Callback> callbacks;
private final List<FlywayCallback> flywayCallbacks;
public FlywayConfiguration(FlywayProperties properties,
DataSourceProperties dataSourceProperties, ResourceLoader resourceLoader,
ObjectProvider<DataSource> dataSource,
@FlywayDataSource ObjectProvider<DataSource> flywayDataSource,
ObjectProvider<FlywayMigrationStrategy> migrationStrategy,
ObjectProvider<FlywayConfigurationCustomizer> fluentConfigurationCustomizers,
ObjectProvider<Callback> callbacks,
ObjectProvider<FlywayCallback> flywayCallbacks) {
this.properties = properties;
this.dataSourceProperties = dataSourceProperties;
this.resourceLoader = resourceLoader;
this.dataSource = dataSource.getIfUnique();
this.flywayDataSource = flywayDataSource.getIfAvailable();
this.migrationStrategy = migrationStrategy.getIfAvailable();
this.configurationCustomizers = fluentConfigurationCustomizers.orderedStream()
.collect(Collectors.toList());
this.callbacks = callbacks.orderedStream().collect(Collectors.toList());
this.flywayCallbacks = flywayCallbacks.orderedStream()
.collect(Collectors.toList());
}
@Bean
public Flyway flyway() {
FluentConfiguration configuration = new FluentConfiguration();
DataSource dataSource = configureDataSource(configuration);
checkLocationExists(dataSource);
configureProperties(configuration);
configureCallbacks(configuration);
this.configurationCustomizers
.forEach((customizer) -> customizer.customize(configuration));
Flyway flyway = configuration.load();
configureFlywayCallbacks(flyway);
return flyway;
}
private DataSource configureDataSource(FluentConfiguration configuration) {
if (this.properties.isCreateDataSource()) {
String url = getProperty(this.properties::getUrl,
this.dataSourceProperties::getUrl);
String user = getProperty(this.properties::getUser,
this.dataSourceProperties::getUsername);
String password = getProperty(this.properties::getPassword,
this.dataSourceProperties::getPassword);
configuration.dataSource(url, user, password);
if (!CollectionUtils.isEmpty(this.properties.getInitSqls())) {
String initSql = StringUtils.collectionToDelimitedString(
this.properties.getInitSqls(), "\n");
configuration.initSql(initSql);
}
}
else if (this.flywayDataSource != null) {
configuration.dataSource(this.flywayDataSource);
}
else {
configuration.dataSource(this.dataSource);
}
return configuration.getDataSource();
}
private void checkLocationExists(DataSource dataSource) {
if (this.properties.isCheckLocation()) {
String[] locations = new LocationResolver(dataSource)
.resolveLocations(this.properties.getLocations());
Assert.state(locations.length != 0,
"Migration script locations not configured");
boolean exists = hasAtLeastOneLocation(locations);
Assert.state(exists, () -> "Cannot find migrations location in: "
+ Arrays.asList(locations)
+ " (please add migrations or check your Flyway configuration)");
}
}
private void configureProperties(FluentConfiguration configuration) {
PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
String[] locations = new LocationResolver(configuration.getDataSource())
.resolveLocations(this.properties.getLocations());
map.from(locations).to(configuration::locations);
map.from(this.properties.getEncoding()).to(configuration::encoding);
map.from(this.properties.getConnectRetries())
.to(configuration::connectRetries);
map.from(this.properties.getSchemas()).as(StringUtils::toStringArray)
.to(configuration::schemas);
map.from(this.properties.getTable()).to(configuration::table);
map.from(this.properties.getBaselineDescription())
.to(configuration::baselineDescription);
map.from(this.properties.getBaselineVersion())
.to(configuration::baselineVersion);
map.from(this.properties.getInstalledBy()).to(configuration::installedBy);
map.from(this.properties.getPlaceholders()).to(configuration::placeholders);
map.from(this.properties.getPlaceholderPrefix())
.to(configuration::placeholderPrefix);
map.from(this.properties.getPlaceholderSuffix())
.to(configuration::placeholderSuffix);
map.from(this.properties.isPlaceholderReplacement())
.to(configuration::placeholderReplacement);
map.from(this.properties.getSqlMigrationPrefix())
.to(configuration::sqlMigrationPrefix);
map.from(this.properties.getSqlMigrationSuffixes())
.as(StringUtils::toStringArray)
.to(configuration::sqlMigrationSuffixes);
map.from(this.properties.getSqlMigrationSeparator())
.to(configuration::sqlMigrationSeparator);
map.from(this.properties.getRepeatableSqlMigrationPrefix())
.to(configuration::repeatableSqlMigrationPrefix);
map.from(this.properties.getTarget()).to(configuration::target);
map.from(this.properties.isBaselineOnMigrate())
.to(configuration::baselineOnMigrate);
map.from(this.properties.isCleanDisabled()).to(configuration::cleanDisabled);
map.from(this.properties.isCleanOnValidationError())
.to(configuration::cleanOnValidationError);
map.from(this.properties.isGroup()).to(configuration::group);
map.from(this.properties.isIgnoreMissingMigrations())
.to(configuration::ignoreMissingMigrations);
map.from(this.properties.isIgnoreIgnoredMigrations())
.to(configuration::ignoreIgnoredMigrations);
map.from(this.properties.isIgnorePendingMigrations())
.to(configuration::ignorePendingMigrations);
map.from(this.properties.isIgnoreFutureMigrations())
.to(configuration::ignoreFutureMigrations);
map.from(this.properties.isMixed()).to(configuration::mixed);
map.from(this.properties.isOutOfOrder()).to(configuration::outOfOrder);
map.from(this.properties.isSkipDefaultCallbacks())
.to(configuration::skipDefaultCallbacks);
map.from(this.properties.isSkipDefaultResolvers())
.to(configuration::skipDefaultResolvers);
map.from(this.properties.isValidateOnMigrate())
.to(configuration::validateOnMigrate);
}
private void configureCallbacks(FluentConfiguration configuration) {
if (!this.callbacks.isEmpty()) {
configuration.callbacks(this.callbacks.toArray(new Callback[0]));
}
}
private void configureFlywayCallbacks(Flyway flyway) {
if (!this.flywayCallbacks.isEmpty()) {
if (!this.callbacks.isEmpty()) {
throw new IllegalStateException(
"Found a mixture of Callback and FlywayCallback beans."
+ " One type must be used exclusively.");
}
flyway.setCallbacks(this.flywayCallbacks.toArray(new FlywayCallback[0]));
}
}
private String getProperty(Supplier<String> property,
Supplier<String> defaultValue) {
String value = property.get();
return (value != null) ? value : defaultValue.get();
}
private boolean hasAtLeastOneLocation(String... locations) {
for (String location : locations) {
if (this.resourceLoader.getResource(normalizePrefix(location)).exists()) {
return true;
}
}
return false;
}
private String normalizePrefix(String location) {
return location.replace("filesystem:", "file:");
}
@Bean
@ConditionalOnMissingBean
public FlywayMigrationInitializer flywayInitializer(Flyway flyway) {
return new FlywayMigrationInitializer(flyway, this.migrationStrategy);
}
/**
* Additional configuration to ensure that {@link EntityManagerFactory} beans
* depend on the {@code flywayInitializer} bean.
*/
@Configuration
@ConditionalOnClass(LocalContainerEntityManagerFactoryBean.class)
@ConditionalOnBean(AbstractEntityManagerFactoryBean.class)
protected static class FlywayInitializerJpaDependencyConfiguration
extends EntityManagerFactoryDependsOnPostProcessor {
public FlywayInitializerJpaDependencyConfiguration() {
super("flywayInitializer");
}
}
/**
* Additional configuration to ensure that {@link JdbcOperations} beans depend on
* the {@code flywayInitializer} bean.
*/
@Configuration
@ConditionalOnClass(JdbcOperations.class)
@ConditionalOnBean(JdbcOperations.class)
protected static class FlywayInitializerJdbcOperationsDependencyConfiguration
extends JdbcOperationsDependsOnPostProcessor {
public FlywayInitializerJdbcOperationsDependencyConfiguration() {
super("flywayInitializer");
}
}
}
/**
* Additional configuration to ensure that {@link EntityManagerFactory} beans depend
* on the {@code flyway} bean.
*/
@Configuration
@ConditionalOnClass(LocalContainerEntityManagerFactoryBean.class)
@ConditionalOnBean(AbstractEntityManagerFactoryBean.class)
protected static class FlywayJpaDependencyConfiguration
extends EntityManagerFactoryDependsOnPostProcessor {
public FlywayJpaDependencyConfiguration() {
super("flyway");
}
}
/**
* Additional configuration to ensure that {@link JdbcOperations} beans depend on the
* {@code flyway} bean.
*/
@Configuration
@ConditionalOnClass(JdbcOperations.class)
@ConditionalOnBean(JdbcOperations.class)
protected static class FlywayJdbcOperationsDependencyConfiguration
extends JdbcOperationsDependsOnPostProcessor {
public FlywayJdbcOperationsDependencyConfiguration() {
super("flyway");
}
}
private static class LocationResolver {
private static final String VENDOR_PLACEHOLDER = "{vendor}";
private final DataSource dataSource;
LocationResolver(DataSource dataSource) {
this.dataSource = dataSource;
}
public String[] resolveLocations(Collection<String> locations) {
return resolveLocations(StringUtils.toStringArray(locations));
}
public String[] resolveLocations(String[] locations) {
if (usesVendorLocation(locations)) {
DatabaseDriver databaseDriver = getDatabaseDriver();
return replaceVendorLocations(locations, databaseDriver);
}
return locations;
}
private String[] replaceVendorLocations(String[] locations,
DatabaseDriver databaseDriver) {
if (databaseDriver == DatabaseDriver.UNKNOWN) {
return locations;
}
String vendor = databaseDriver.getId();
return Arrays.stream(locations)
.map((location) -> location.replace(VENDOR_PLACEHOLDER, vendor))
.toArray(String[]::new);
}
private DatabaseDriver getDatabaseDriver() {
try {
String url = JdbcUtils.extractDatabaseMetaData(this.dataSource, "getURL");
return DatabaseDriver.fromJdbcUrl(url);
}
catch (MetaDataAccessException ex) {
throw new IllegalStateException(ex);
}
}
private boolean usesVendorLocation(String... locations) {
for (String location : locations) {
if (location.contains(VENDOR_PLACEHOLDER)) {
return true;
}
}
return false;
}
}
/**
* Convert a String or Number to a {@link MigrationVersion}.
*/
private static class StringOrNumberToMigrationVersionConverter
implements GenericConverter {
private static final Set<ConvertiblePair> CONVERTIBLE_TYPES;
static {
Set<ConvertiblePair> types = new HashSet<>(2);
types.add(new ConvertiblePair(String.class, MigrationVersion.class));
types.add(new ConvertiblePair(Number.class, MigrationVersion.class));
CONVERTIBLE_TYPES = Collections.unmodifiableSet(types);
}
@Override
public Set<ConvertiblePair> getConvertibleTypes() {
return CONVERTIBLE_TYPES;
}
@Override
public Object convert(Object source, TypeDescriptor sourceType,
TypeDescriptor targetType) {
String value = ObjectUtils.nullSafeToString(source);
return MigrationVersion.fromVersion(value);
}
}
}
