关于Ant的Copy Task

　　一个配置文件是xml格式的，里边有中文字段，编码格式为UTF-8，在Unit Test里边跑没有问题，用ant发布到服务器上就出xml解析异常：Invalid byte 3 of 3-byte UTF-8 sequence。打开服务器上的文件，是乱码，根源是ant的Copy Task的问题。在Ant的文档（http://ant.apache.org/manual/CoreTasks/copy.html）中是如此记述的：

Important Encoding Note:  The reason that binary files when filtered get corrupted is that filtering involves reading in the file using a Reader class. This has an encoding specifing how files are encoded. There are a number of different types of encoding - UTF-8, UTF-16, Cp1252, ISO-8859-1, US-ASCII and (lots) others. On Windows the default character encoding is Cp1252, on Unix it is usually UTF-8. For both of these encoding there are illegal byte sequences (more in UTF-8 than for Cp1252).

How the Reader class deals with these illegal sequences is up to the implementation of the character decoder. The current Sun Java implemenation is to map them to legal characters. Previous Sun Java (1.3 and lower) threw a MalformedInputException. IBM Java 1.4 also thows this exception. It is the mapping of the characters that cause the corruption.

On Unix, where the default is normally UTF-8, this is a big problem, as it is easy to edit a file to contain non US Ascii characters from ISO-8859-1, for example the Danish oe character. When this is copied (with filtering) by Ant, the character get converted to a question mark (or some such thing).

There is not much that Ant can do. It cannot figure out which files are binary - a UTF-8 version of Korean will have lots of bytes with the top bit set. It is not informed about illegal character sequences by current Sun Java implementions.

One trick for filtering containing only US-ASCII is to use the ISO-8859-1 encoding. This does not seem to contain illegal character sequences, and the lower 7 bits are US-ASCII. Another trick is to change the LANG environment variable from something like "us.utf8" to "us".

在copy标签上加上encoding="UTF-8"，问题解决了。