Buffering
A servlet container is allowed, but not required, to buffer output going to the client for efficiency purposes. Typically servers that do buffering make it the default, but allow servlets to specify buffering parameters.
The following methods in the ServletResponse interface allow a servlet to access and set buffering information:
=> getBufferSize
=> setBufferSize
=> isCommitted
=> reset
=> resetBuffer
=> flushBuffer
These methods are provided on the ServletResponse interface to allow buffering operations to be performed whether the servlet is using a ServletOutputStream or a Writer.
The getBufferSize method returns the size of the underlying buffer being used. If no buffering is being used, this method must return the int value of 0 (zero).
The servlet can request a preferred buffer size by using the setBufferSize method. The buffer assigned is not required to be the size requested by the servlet, but must be at least as large as the size requested. This allows the container to reuse a set of fixed size buffers, providing a larger buffer than requested if appropriate. The method must be called before any content is written using a ServletOutputStream or Writer. If any content has been written or the response object has been committed, this method must throw an IllegalStateException.
The isCommitted method returns a boolean value indicating whether any response bytes have been returned to the client. The flushBuffer method forces content in the buffer to be written to the client.
The reset method clears data in the buffer when the response is not committed. Headers and status codes set by the servlet prior to the reset call must be cleared as well. The resetBuffer method clears content in the buffer if the response is not committed without clearing the headers and status code.
If the response is committed and the reset or resetBuffer method is called, an IllegalStateException must be thrown. The response and its associated buffer will be unchanged.
When using a buffer, the container must immediately flush the contents of a filled buffer to the client. If this is the first data is sent to the client, the response is considered to be committed.
The following methods in the ServletResponse interface allow a servlet to access and set buffering information:
=> getBufferSize
=> setBufferSize
=> isCommitted
=> reset
=> resetBuffer
=> flushBuffer
These methods are provided on the ServletResponse interface to allow buffering operations to be performed whether the servlet is using a ServletOutputStream or a Writer.
The getBufferSize method returns the size of the underlying buffer being used. If no buffering is being used, this method must return the int value of 0 (zero).
The servlet can request a preferred buffer size by using the setBufferSize method. The buffer assigned is not required to be the size requested by the servlet, but must be at least as large as the size requested. This allows the container to reuse a set of fixed size buffers, providing a larger buffer than requested if appropriate. The method must be called before any content is written using a ServletOutputStream or Writer. If any content has been written or the response object has been committed, this method must throw an IllegalStateException.
The isCommitted method returns a boolean value indicating whether any response bytes have been returned to the client. The flushBuffer method forces content in the buffer to be written to the client.
The reset method clears data in the buffer when the response is not committed. Headers and status codes set by the servlet prior to the reset call must be cleared as well. The resetBuffer method clears content in the buffer if the response is not committed without clearing the headers and status code.
If the response is committed and the reset or resetBuffer method is called, an IllegalStateException must be thrown. The response and its associated buffer will be unchanged.
When using a buffer, the container must immediately flush the contents of a filled buffer to the client. If this is the first data is sent to the client, the response is considered to be committed.
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