java.lang.IllegalStateException: Cannot forward after response has been committed

发送get或post请求时，抛出如下异常：

java.lang.IllegalStateException: Cannot forward after response has been committed

异常说明response被委派了两次。

解决办法：

将doGet方法中继承超类的方法屏蔽。

重载父类的方法，会抛出response已经被提交的异常。