聊聊spring boot tomcat jdbc pool的属性绑定

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 ; } 复制代码

可以看到这里的DataSourceProperties仅仅只有spring.datasource直接属性的配置，比如url，username，password，driverClassName。tomcat的具体属性都没有。

createDataSource

protected <T> T createDataSource(DataSourceProperties properties,
            Class<? extends DataSource> type) {
        return (T) properties.initializeDataSourceBuilder().type(type).build();
    }复制代码

直接createDataSource出来的org.apache.tomcat.jdbc.pool.DataSource的PoolProperties也是默认的配置

ConfigurationProperties

具体的魔力就在于@ConfigurationProperties(prefix = "spring.datasource.tomcat")这段代码，它在spring容器构造好代理bean返回之前会将spring.datasource.tomcat指定的属性设置到org.apache.tomcat.jdbc.pool.DataSource

spring-boot-1.5.9.RELEASE-sources.jar!/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java

private 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);
    }复制代码

注意，这里的annotation就是@ConfigurationProperties(prefix = "spring.datasource.tomcat")，它的prefix是spring.datasource.tomcat
PropertiesConfigurationFactory的targetName就是spring.datasource.tomcat

PropertiesConfigurationFactory.bindPropertiesToTarget

spring-boot-1.5.9.RELEASE-sources.jar!/org/springframework/boot/bind/PropertiesConfigurationFactory.java

    public 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);
    }复制代码

委托给doBindPropertiesToTarget方法

PropertiesConfigurationFactory.doBindPropertiesToTarget

private 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);
    }复制代码

这里借助RelaxedDataBinder.bind方法

getRelaxedTargetNames

    private Iterable<String> getRelaxedTargetNames() {
        return (this.target != null && StringUtils.hasLength(this.targetName)
                ? new RelaxedNames(this.targetName) : null);
    }复制代码

这里new了一个RelaxedNames，可以识别多个变量的变种

RelaxedNames

spring-boot-1.5.9.RELEASE-sources.jar!/org/springframework/boot/bind/RelaxedNames.java

    private 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);
    }复制代码

即支持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]]这7中配置的写法

getPropertySourcesPropertyValues

    private PropertyValues getPropertySourcesPropertyValues(Set<String> names,
            Iterable<String> relaxedTargetNames) {
        PropertyNamePatternsMatcher includes = getPropertyNamePatternsMatcher(names,
                relaxedTargetNames);
        return new PropertySourcesPropertyValues(this.propertySources, names, includes,
                this.resolvePlaceholders);
    }复制代码

这个方法会把spring.datasource.tomact底下的属性配置拉取到PropertyValues对象里头

RelaxedDataBinder.bind

spring-boot-1.5.9.RELEASE-sources.jar!/org/springframework/boot/bind/RelaxedDataBinder.java的bind方法调用的是父类的方法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 (); } 复制代码

最后通过getPropertyAccessor()来设置，这个propertyAccessor就是org.springframework.boot.bind.RelaxedDataBinder$RelaxedBeanWrapper: wrapping object [org.apache.tomcat.jdbc.pool.DataSource@6a84bc2a]，也就包装的org.apache.tomcat.jdbc.pool.DataSource

AbstractPropertyAccessor.setPropertyValues

spring-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);
    }复制代码

这里的nestedPa.setPropertyValue(tokens, pv);真正把spring.datasource.tomcat的属性值设置进去
这里的nestedPa就是org.springframework.boot.bind.RelaxedDataBinder$RelaxedBeanWrapper: wrapping object [org.apache.tomcat.jdbc.pool.DataSource@6a84bc2a]
最后是调用AbstractNestablePropertyAccessor.processLocalProperty

AbstractNestablePropertyAccessor.processLocalProperty

spring-beans-4.3.13.RELEASE-sources.jar!/org/springframework/beans/AbstractNestablePropertyAccessor.java

private 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 instanceof UndeclaredThrowableException) {
                    // May happen e.g. 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);
    }复制代码

它使其是使用class org.springframework.beans.BeanWrapperImpl$BeanPropertyHandler来设置

BeanWrapperImpl$BeanPropertyHandler.setValue

spring-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);
    }复制代码

这里利用反射找出setXXX方法( 比如setMaxActive )，然后设置进去

多数据源的配置

上面的配置对于单数据源来说是没有问题的，对于多数据源，则配置如下

@Configuration
public class MasterDatasourceConfig {
    @Bean("masterDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.master")
    public DataSource masterDataSource() {
        return DataSourceBuilder.create().build();
}    复制代码

注意，这里要添加ConfigurationProperties注入tomcat jdbc pool的额外设置

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: ## 多数据源的话,这里要去掉tomcat,通通放在数据源前缀下面
      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复制代码

原先tomcat的配置都要放在数据源前缀的底下，放在spring.datasource.tomcat或者spring.datasource.master.tomcat底下均无法生效。

spirngboot的自动配置是挺方便的，但是在实际应用的场景下还需要了解底层机制才可以，否则容易出来配置假象，以为配置对了，实际没生效。

boot-features-configure-datasource