对象池主要管理对象的池，包含借用，归还，添加对象，校验对象是否有效等管理功能
public T borrowObject(final long borrowMaxWaitMillis) throws Exception {assertOpen();final AbandonedConfig ac = this.abandonedConfig;if (ac != null && ac.getRemoveAbandonedOnBorrow() &&(getNumIdle() < 2) &&(getNumActive() > getMaxTotal() - 3) ) {removeAbandoned(ac);}PooledObject<T> p = null;// Get local copy of current config so it is consistent for entire// method executionfinal boolean blockWhenExhausted = getBlockWhenExhausted();boolean create;final long waitTime = System.currentTimeMillis();while (p == null) {create = false;p = idleObjects.pollFirst();if (p == null) {p = create();if (p != null) {create = true;}}if (blockWhenExhausted) {if (p == null) {if (borrowMaxWaitMillis < 0) {p = idleObjects.takeFirst();} else {p = idleObjects.pollFirst(borrowMaxWaitMillis,TimeUnit.MILLISECONDS);}}if (p == null) {throw new NoSuchElementException("Timeout waiting for idle object");}} else {if (p == null) {throw new NoSuchElementException("Pool exhausted");}}if (!p.allocate()) {p = null;}if (p != null) {try {factory.activateObject(p);} catch (final Exception e) {try {destroy(p);} catch (final Exception e1) {// Ignore - activation failure is more important}p = null;if (create) {final NoSuchElementException nsee = new NoSuchElementException("Unable to activate object");nsee.initCause(e);throw nsee;}}if (p != null && getTestOnBorrow()) {boolean validate = false;Throwable validationThrowable = null;try {validate = factory.validateObject(p);} catch (final Throwable t) {PoolUtils.checkRethrow(t);validationThrowable = t;}if (!validate) {try {destroy(p);destroyedByBorrowValidationCount.incrementAndGet();} catch (final Exception e) {// Ignore - validation failure is more important}p = null;if (create) {final NoSuchElementException nsee = new NoSuchElementException("Unable to validate object");nsee.initCause(validationThrowable);throw nsee;}}}}}updateStatsBorrow(p, System.currentTimeMillis() - waitTime);return p.getObject();}参考引用
对象池（连接池）：commons-pool2源码解析：GenericObjectPool的继承结构、构造方法_genericobjectpool idleobjects-CSDN博客
