Let’s take a look at the property binding code of spring boot tomcat jdbc pool. The specific code is as follows:
spring: datasource: type: org.apache.tomcat.jdbc.pool.DataSource driver-class-name: org.postgresql.Driver url: jdbc:postgresql://192.168.99.100:5432/postgres?connectTimeout=6000&socketTimeout=6000 username: postgres password: postgres jmx-enabled: true initial-size: 1 max-active: 5 ## when pool sweater is enabled, extra idle connection will be closed max-idle: 5 ## when idle connection > min-idle, poolSweeper will start to close min-idle: 1
Using the above configuration, I finally found that initial-size, max-active, max-idle, min-idle and other configurations are invalid. The generated tomcat jdbc datasource is still the default configuration used.
Correct configuration
spring: datasource: type: org.apache.tomcat.jdbc.pool.DataSource driver-class-name: org.postgresql.Driver url: jdbc:postgresql://192.168.99.100:5432/postgres?connectTimeout=6000&socketTimeout=6000 username: postgres password: postgres jmx-enabled: true tomcat: ## A single database connection pool, and the tomcat property configuration must be written to take effect initial-size: 1 max-active: 5 ## when pool sweeper is enabled, extra idle connection will be closed max-idle: 5 ## when idle connection > min-idle, poolSweeper will start to close min-idle: 1
Note that the configuration properties of the specific tomcat database connection pool are placed under the spring.datasource.tomcat property so that they can take effect.
Source code analysis
spring-boot-autoconfigure-1.5.9.RELEASE-sources.jar!/org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfiguration.java@Configuration @Conditional(PooledDataSourceCondition.class) @ConditionalOnMissingBean({ DataSource.class, XADataSource.class }) @Import({ DataSourceConfiguration.Tomcat.class, DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Dbcp.class, DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.Generic.class }) @SuppressWarnings("deprecation") protected static class PooledDataSourceConfiguration { }DataSourceConfiguration.Tomcat
spring-boot-autoconfigure-1.5.9.RELEASE-sources.jar!/org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration.java/** * Tomcat Pool DataSource configuration. */ @ConditionalOnClass(org.apache.tomcat.jdbc.pool.DataSource.class) @ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.tomcat.jdbc.pool.DataSource", matchIfMissing = true) static class Tomcat extends DataSourceConfiguration { @Bean @ConfigurationProperties(prefix = "spring.datasource.tomcat") public org.apache.tomcat.jdbc.pool.DataSource dataSource(DataSourceProperties properties) { org.apache.tomcat.jdbc.pool.DataSource dataSource = createDataSource( properties, org.apache.tomcat.jdbc.pool.DataSource.class); DatabaseDriver databaseDriver = DatabaseDriver .fromJdbcUrl(properties.determineUrl()); String validationQuery = databaseDriver.getValidationQuery(); if (validationQuery != null) { dataSource.setTestOnBorrow(true); dataSource.setValidationQuery(validationQuery); } return dataSource; } }You can see that the DataSourceProperties here only has the configuration of spring.datasource direct attributes, such as url, username, password, driverClassName. Tomcat has no specific properties.
createDataSource
protected <T> T createDataSource(DataSourceProperties properties, Class<? extends DataSource> type) { return (T) properties.initializeDataSourceBuilder().type(type).build(); }The org.apache.tomcat.jdbc.pool.DataSource PoolProperties that directly createDataSource is also the default configuration.
ConfigurationProperties
The specific magic lies in the code @ConfigurationProperties(prefix = "spring.datasource.tomcat") . Before the spring container constructs the proxy bean and returns, it will set the attribute specified by spring.datasource.tomcat to org.apache.tomcat.jdbc.pool.DataSource
spring-boot-1.5.9.RELEASE-sources.jar!/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.javaprivate void postProcessBeforeInitialization(Object bean, String beanName, ConfigurationProperties annotation) { Object target = bean; PropertiesConfigurationFactory<Object> factory = new PropertiesConfigurationFactory<Object>( target); factory.setPropertySources(this.propertySources); factory.setValidator(determineValidator(bean)); // If no explicit conversion service is provided we add one so that (at least) // comma-separated arrays of convertibles can be bound automatically factory.setConversionService(this.conversionService == null ? getDefaultConversionService() : this.conversionService); if (annotation != null) { factory.setIgnoreInvalidFields(annotation.ignoreInvalidFields()); factory.setIgnoreUnknownFields(annotation.ignoreUnknownFields()); factory.setExceptionIfInvalid(annotation.exceptionIfInvalid()); factory.setIgnoreNestedProperties(annotation.ignoreNestedProperties()); if (StringUtils.hasLength(annotation.prefix())) { factory.setTargetName(annotation.prefix()); } } try { factory.bindPropertiesToTarget(); } catch (Exception ex) { String targetClass = ClassUtils.getShortName(target.getClass()); throw new BeanCreationException(beanName, "Could not bind properties to " + targetClass + " (" + getAnnotationDetails(annotation) + ")", ex); } } Note that the annotation here is @ConfigurationProperties(prefix = "spring.datasource.tomcat") , its prefix is spring.datasource.tomcat PropertiesConfigurationFactory targetName is spring.datasource.tomcat
PropertiesConfigurationFactory.bindPropertiesToTargetspring-boot-1.5.9.RELEASE-sources.jar!/org/springframework/boot/bind/PropertiesConfigurationFactory.javapublic void bindPropertiesToTarget() throws BindException { Assert.state(this.propertySources != null, "PropertySources should not be null"); try { if (logger.isTraceEnabled()) { logger.trace("Property Sources: " + this.propertySources); } this.hasBeenBound = true; doBindPropertiesToTarget(); } catch (BindException ex) { if (this.exceptionIfInvalid) { throw ex; } PropertiesConfigurationFactory.logger .error("Failed to load Properties validation bean. " + "Your Properties may be invalid.", ex); } }Delegate to doBindPropertiesToTarget method
PropertiesConfigurationFactory.doBindPropertiesToTargetprivate void doBindPropertiesToTarget() throws BindException { RelaxedDataBinder dataBinder = (this.targetName != null ? new RelaxedDataBinder(this.target, this.targetName) : new RelaxedDataBinder(this.target)); if (this.validator != null && this.validator.supports(dataBinder.getTarget().getClass())) { dataBinder.setValidator(this.validator); } if (this.conversionService != null) { dataBinder.setConversionService(this.conversionService); } dataBinder.setAutoGrowCollectionLimit(Integer.MAX_VALUE); dataBinder.setIgnoreNestedProperties(this.ignoreNestedProperties); dataBinder.setIgnoreInvalidFields(this.ignoreInvalidFields); dataBinder.setIgnoreUnknownFields(this.ignoreUnknownFields); customizeBinder(dataBinder); Iterable<String> relaxedTargetNames = getRelaxedTargetNames(); Set<String> names = getNames(relaxedTargetNames); PropertyValues propertyValues = getPropertySourcesPropertyValues(names, relaxedTargetNames); dataBinder.bind(propertyValues); if (this.validator != null) { dataBinder.validate(); } checkForBindingErrors(dataBinder); }Here, use the RelaxedDataBinder.bind method
getRelaxedTargetNamesprivate Iterable<String> getRelaxedTargetNames() { return (this.target != null && StringUtils.hasLength(this.targetName) ? new RelaxedNames(this.targetName) : null); }Here is a new RelaxedNames that can identify variants of multiple variables
RelaxedNames
spring-boot-1.5.9.RELEASE-sources.jar!/org/springframework/boot/bind/RelaxedNames.javaprivate void initialize(String name, Set<String> values) { if (values.contains(name)) { return; } for (Variation variation : Variation.values()) { for (Manipulation manipulation : Manipulation.values()) { String result = name; result = manipulation.apply(result); result = variation.apply(result); values.add(result); initialize(result, values); } } } /** * Name variations. */ enum Variation { NONE { @Override public String apply(String value) { return value; } }, LOWERCASE { @Override public String apply(String value) { return value.isEmpty() ? value : value.toLowerCase(); } }, UPPERCASE { @Override public String apply(String value) { return value.isEmpty() ? value : value.toUpperCase(); } }; public abstract String apply(String value); }That is, the writing method of configuration in org.springframework.boot.bind.RelaxedNames@6ef81f31[name=spring.datasource.tomcat, values=[spring.datasource.tomcat, spring_datasource_tomcat, springDatasourceTomcat, springdatasourcetomcat, SPRING.DATASOURCE.TOMCAT, SPRING_DATASOURCE_TOMCAT, SPRINGDATASOURCETOMCAT]] is supported.
getPropertySourcesPropertyValuesprivate PropertyValues getPropertySourcesPropertyValues(Set<String> names, Iterable<String> relaxedTargetNames) { PropertyNamePatternsMatcher include = getPropertyNamePatternsMatcher(names, relaxedTargetNames); return new PropertySourcesPropertyValues(this.propertySources, names, includes, this.resolvePlaceholders); }This method will pull the property configuration under spring.datasource.tomact into the PropertyValues object
RelaxedDataBinder.bind
spring-boot-1.5.9.RELEASE-sources.jar!/org/springframework/boot/bind/RelaxedDataBinder.java's bind method calls the parent class's method spring-context-4.3.13.RELEASE-sources.jar!/org/springframework/validation/DataBinder.java/** * Bind the given property values to this binder's target. * <p>This call can create field errors, representing basic binding * errors like a required field (code "required"), or type mismatch * between value and bean property (code "typeMismatch"). * <p>Note that the given PropertyValues should be a throwaway instance: * For efficiency, it will be modified to just contain allowed fields if it * implements the MutablePropertyValues interface; else, an internal mutable * copy will be created for this purpose. Pass in a copy of the PropertyValues * if you want your original instance to stay unmodified in any case. * @param pvs property values to bind * @see #doBind(org.springframework.beans.MutablePropertyValues) */ public void bind(PropertyValues pvs) { MutablePropertyValues mpvs = (pvs instanceof MutablePropertyValues) ? (MutablePropertyValues) pvs : new MutablePropertyValues(pvs); doBind(mpvs); } /** * Actual implementation of the binding process, working with the * passed-in MutablePropertyValues instance. * @param mpvs the property values to bind, * as MutablePropertyValues instance * @see #checkAllowedFields * @see #checkRequiredFields * @see #applyPropertyValues */ protected void doBind(MutablePropertyValues mpvs) { checkAllowedFields(mpvs); checkRequiredFields(mpvs); applyPropertyValues(mpvs); } /** * Apply given property values to the target object. * <p>Default implementation applies all of the supplied property * values as bean property values. By default, unknown fields will * be ignored. * @param mpvs the property values to be bound (can be modified) * @see #getTarget * @see #getPropertyAccessor * @see #isIgnoreUnknownFields * @see #getBindingErrorProcessor * @see BindingErrorProcessor#processPropertyAccessException */ protected void applyPropertyValues(MutablePropertyValues mpvs) { try { // Bind request parameters onto target object. getPropertyAccessor().setPropertyValues(mpvs, isIgnoreUnknownFields(), isIgnoreInvalidFields()); } catch (PropertyBatchUpdateException ex) { // Use bind error processor to create FieldErrors. for (PropertyAccessException pae : ex.getPropertyAccessExceptions()) { getBindingErrorProcessor().processPropertyAccessException(pae, getInternalBindingResult()); } } } /** * Return the underlying PropertyAccessor of this binder's BindingResult. */ protected ConfigurablePropertyAccessor getPropertyAccessor() { return getInternalBindingResult().getPropertyAccessor(); }Finally, it is set by getPropertyAccessor(). This propertyAccessor is org.springframework.boot.bind.RelaxedDataBinder$RelaxedBeanWrapper: wrapping object [org.apache.tomcat.jdbc.pool.DataSource@6a84bc2a], which is the wrapped org.apache.tomcat.jdbc.pool.DataSource
AbstractPropertyAccessor.setPropertyValuesspring-beans-4.3.13.RELEASE-sources.jar!/org/springframework/beans/AbstractPropertyAccessor.java@Override public void setPropertyValues(PropertyValues pvs, boolean ignoreUnknown, boolean ignoreInvalid) throws BeansException { List<PropertyAccessException> propertyAccessExceptions = null; List<PropertyValue> propertyValues = (pvs instanceof MutablePropertyValues ? ((MutablePropertyValues) pvs).getPropertyValueList() : Arrays.asList(pvs.getPropertyValues())); for (PropertyValue pv : propertyValues) { try { // This method may throw any BeansException, which won't be caught // here, if there is a critical failure such as no matching field. // We can attempt to deal only with less serious exceptions. setPropertyValue(pv); } catch (NotWritablePropertyException ex) { if (!ignoreUnknown) { throw ex; } // Otherwise, just ignore it and continue... } catch (NullValueInNestedPathException ex) { if (!ignoreInvalid) { throw ex; } // Otherwise, just ignore it and continue... } catch (PropertyAccessException ex) { if (propertyAccessExceptions == null) { propertyAccessExceptions = new LinkedList<PropertyAccessException>(); } propertyAccessExceptions.add(ex); } } // If we encountered individual exceptions, throw the composite exception. if (propertyAccessExceptions != null) { PropertyAccessException[] paeArray = propertyAccessExceptions.toArray(new PropertyAccessException[propertyAccessExceptions.size()]); throw new PropertyBatchUpdateException(paeArray); } } @Override public void setPropertyValue(PropertyValue pv) throws BeansException { PropertyTokenHolder tokens = (PropertyTokenHolder) pv.resolvedTokens; if (tokens == null) { String propertyName = pv.getName(); AbstractNestablePropertyAccessor nestedPa; try { nestedPa = getPropertyAccessorForPropertyPath(propertyName); } catch (NotReadablePropertyException ex) { throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName, "Nested property in path '" + propertyName + "' does not exist", ex); } tokens = getPropertyNameTokens(getFinalPath(nestedPa, propertyName)); if (nestedPa == this) { pv.getOriginalPropertyValue().resolvedTokens = tokens; } nestedPa.setPropertyValue(tokens, pv); } else { setPropertyValue(tokens, pv); } }Here nestedPa.setPropertyValue(tokens, pv); The real setting of spring.datasource.tomcat property value is org.springframework.boot.bind.RelaxedDataBinder$RelaxedBeanWrapper: wrapping object [org.apache.tomcat.jdbc.pool.DataSource@6a84bc2a] Finally, call AbstractNestablePropertyAccessor.processLocalProperty
AbstractNestablePropertyAccessor.processLocalPropertyspring-beans-4.3.13.RELEASE-sources.jar!/org/springframework/beans/AbstractNestablePropertyAccessor.javaprivate void processLocalProperty(PropertyTokenHolder tokens, PropertyValue pv) { PropertyHandler ph = getLocalPropertyHandler(tokens.actualName); if (ph == null || !ph.isWritable()) { if (pv.isOptional()) { if (logger.isDebugEnabled()) { logger.debug("Ignoring optional value for property '" + tokens.actualName + "' - property not found on bean class [" + getRootClass().getName() + "]"); } return; } else { throw createNotWritablePropertyException(tokens.canonicalName); } } Object oldValue = null; try { Object originalValue = pv.getValue(); Object valueToApply = originalValue; if (!Boolean.FALSE.equals(pv.conversionNecessary)) { if (pv.isConverted()) { valueToApply = pv.getConvertedValue(); } else { if (isExtractOldValueForEditor() && ph.isReadable()) { try { oldValue = ph.getValue(); } catch (Exception ex) { if (ex instanceof PrivilegedActionException) { ex = ((PrivilegedActionException) ex).getException(); } if (logger.isDebugEnabled()) { logger.debug("Could not read previous value of property '" + this.nestedPath + tokens.canonicalName + "'", ex); } } valueToApply = convertForProperty( tokens.canonicalName, oldValue, originalValue, ph.toTypeDescriptor()); } pv.getOriginalPropertyValue().conversionNecessary = (valueToApply != originalValue); } ph.setValue(this.wrappedObject, valueToApply); } catch (TypeMismatchException ex) { throw ex; } catch (InvocationTargetException ex) { PropertyChangeEvent propertyChangeEvent = new PropertyChangeEvent( this.rootObject, this.nestedPath + tokens.canonicalName, oldValue, pv.getValue()); if (ex.getTargetException() instanceof ClassCastException) { throw new TypeMismatchException(propertyChangeEvent, ph.getPropertyType(), ex.getTargetException()); } else { Throwable cause = ex.getTargetException(); if (cause instance of UndeclaredThrowableException) { // May happen eg with Groovy-generated methods cause = cause.getCause(); } throw new MethodInvocationException(propertyChangeEvent, cause); } } catch (Exception ex) { PropertyChangeEvent pce = new PropertyChangeEvent( this.rootObject, this.nestedPath + tokens.canonicalName, oldValue, pv.getValue()); throw new MethodInvocationException(pce, ex); } }It makes it set using class org.springframework.beans.BeanWrapperImpl$BeanPropertyHandler
BeanWrapperImpl$BeanPropertyHandler.setValuespring-beans-4.3.13.RELEASE-sources.jar!/org/springframework/beans/BeanWrapperImpl.java@Override public void setValue(final Object object, Object valueToApply) throws Exception { final Method writeMethod = (this.pd instanceof GenericTypeAwarePropertyDescriptor ? ((GenericTypeAwarePropertyDescriptor) this.pd).getWriteMethodForActualAccess() : this.pd.getWriteMethod()); if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers()) && !writeMethod.isAccessible()) { if (System.getSecurityManager() != null) { AccessController.doPrivileged(new PrivilegedAction<Object>() { @Override public Object run() { writeMethod.setAccessible(true); return null; } }); } else { writeMethod.setAccessible(true); } } final Object value = valueToApply; if (System.getSecurityManager() != null) { try { AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() { @Override public Object run() throws Exception { writeMethod.invoke(object, value); return null; } }, acc); } catch (PrivilegedActionException ex) { throw ex.getException(); } } else { writeMethod.invoke(getWrappedInstance(), value); } } } }Here we use reflection to find the setXXX method (such as setMaxActive), and then set it in
Multi-data source configuration
The above configuration is not problematic for a single data source. For multiple data sources, the configuration is as follows
@Configurationpublic class MasterDatasourceConfig { @Bean("masterDataSource") @ConfigurationProperties(prefix = "spring.datasource.master") public DataSource masterDataSource() { return DataSourceBuilder.create().build(); }}Note that you need to add additional settings to inject the configurationProperties into tomcat jdbc pool
spring: datasource: master: type: org.apache.tomcat.jdbc.pool.DataSource driver-class-name: org.postgresql.Driver url: jdbc:postgresql://192.168.99.100:5432/postgres?connectTimeout=6000&socketTimeout=6000 username: postgres password: postgres jmx-enabled: true# tomcat: ## For multiple data sources, we need to remove tomcat here and put them under the prefix of the data source initial-size: 1 max-active: 5 ## when pool sweeper is enabled, extra idle connection will be closed max-idle: 5 ## when idle connection > min-idle, poolSweeper will start to close min-idle: 1
The original tomcat configuration must be placed under the data source prefix, and it cannot take effect under spring.datasource.tomcat or spring.datasource.master.tomcat.