一、 文档API
reset
- public void reset()
Clears any data that exists in the buffer as well as the status code and headers. If the response has been committed, this method throws an IllegalStateException.
- Throws:
java.lang.IllegalStateException - if the response has already been committed
- See Also:
setBufferSize(int), getBufferSize(), flushBuffer(), isCommitted()
resetBuffer
- public void resetBuffer()
Clears the content of the underlying buffer in the response without clearing headers or status code. If the response has been committed, this method throws an IllegalStateException.
- Since:
2.3
- See Also:
setBufferSize(int), getBufferSize(), isCommitted(), reset()
二、文档释义
getResponse的getWriter()方法
getResponse的getWriter()方法连续两次输出流到页面的时候，第二次的流会包括第一次的流，所以可以使用response.reset或者resetBuffer的方法。
reset():
Clears any data that exists in the buffer as well as the status code and headers. If the response has been committed, this method throws an IllegalStateException.
response.reset()的使用有一个条件受限：response的任何打开流关闭之后都不能再reset .
resetBuffer():
Clears the content of the underlying buffer in the response without clearing headers or status code. If the response has been committed, this method throws an IllegalStateException
可以看到resetBuffer方法与reset方法的区别是，头和状态码没有清除。
- 一般用于下载文件excel操作时：
空白行的出现原因，jsp代码编译后产生。就是有jsp生成html文件的时候，html文件内部会出现很多空白行。下载后的文件内的空白行也是这样产生的。
因此，需要 response.reset() 来清除首部的空白行。