终结Oreilly的《Java网络编程》-UDP包与URLConnection(部分）[7]

·   The read method of the underlying stream returns -1, indicating end-of-file, or

·   The available method of the underlying stream returns zero, indicating that further input requests would block.

If the first read on the underlying stream returns -1 to indicate end-of-file then this method returns -1. Otherwise this method returns the number of bytes actually read.

Public String getContentEncoding()

Public long getDate()

Public long getExpiration()

Public long getLastModified()

检索临时MIME首部字段

上面所描述的过于固定也过于不灵活，我们有更动态的方法来获得MIME首部字段：

Public  String getHeaderField(String name)

                            Name=  Content-type;

                                          Content-encoding;

                                          Date;