spring boot tomcat jdbc pool的属性绑定

下面看下spring boot tomcat jdbc pool的属性绑定代码，具体代码如下所示：

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 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

使用如上配置，最后发现initial-size，max-active，max-idle，min-idle等配置均无效，生成的tomcat jdbc datasource还是使用的默认的配置

正确配置

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: ## 单个数据库连接池,而且得写上tomcat的属性配置才可以生效
  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

注意，这里把具体tomcat数据库连接池的配置属性放到了spring.datasource.tomcat属性下面，这样才可以生效。

源码解析

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;
 }
 }

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();
 }

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);
 }
 }

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);
 }
 }

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);
 }

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);
 }

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);
 }

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);
 }

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();
 }

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);
 }
 }

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);
 }
 }

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);
 }
 }
 }

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();
 }
}

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

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。