请问 ServletInputStream的 read(byte[], int, int)方法一次最多能读取多少字符？

码拜

10年 ago

在struts中写了一个Filter，实现以下功能：使用ServletInputStream中的read(byte[] buff, int offset, int length)这个方法，读取http post消息中的body数据。代码如下： int readIndex = 0; int readCount = 0; InputStream sis = request.getInputStream(); do { readCount = sis.read(jsonBuf, readIndex, contentLength - readIndex + 1); readIndex += readCount; } while( readCount > 0); 由于body中传输的数据比较大，do while的循环体会执行多次。尽管read最后一个参数设置为10000，但是第一次读取的数据大小readCount仍然是7000多。请问：每次读取的 readCount的大小是由什么来决定的呢？
	http://www.cnblogs.com/MyFavorite/archive/2010/10/19/1855758.html
20分	public int read(byte[] b, int off, int len) throws IOException Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown. If b is null, a NullPointerException is thrown. If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown. If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b. The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected. In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected. If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed. The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. Subclasses are encouraged to provide a more efficient implementation of this method.
	具体的不清楚，但肯定收到网络的影响。你可以做一个实验，自己大奖一个iis，下载一个文件，iis可以限制速度，这样可以看到每次读出的长度。但是这个也是在局域网中，每次读出的数据量收到iis下载速度的限制，如果是在Internet，可能更加复杂一下。
	引用 1 楼 shixitong 的回复: http://www.cnblogs.com/MyFavorite/archive/2010/10/19/1855758.html 不好意思，怎么直接给分？我刚才结贴的时候填写了20分，但是现在看到分没给出来····