困惑了半年的用Prototype在url中传特殊符号的问题终于解决了！

The escape() function encodes a string, so it can be read on all computers.


Syntax

escape(string)

Parameter Description
string Required. The string to be encoded


Tips and Notes

Note: The escape() function encodes special characters, with the exception of:
* @ - _ + . /

Tip: Use the unescape() function to decode strings encoded with escape().

Note: The escape() and unescape() functions should not be used to encode or decode URIs. Use encodeURI() and decodeURI() functions instead!
Example

In this example we use escape() to encode strings:<script type="text/javascript">
document.write(escape("Visit W3Schools!") + "<br />");
document.write(escape("?!=()#%&"));
</script>


The output of the code above will be:

Visit%20W3Schools%21
%3F%21%3D%28%29%23%25%26

在自己的例子中：

function openFile(){
    var dir = document.getElementById("ontology").value;
    _dir = escape(dir);//unescape(String s)
    new Ajax.Request('/annotate/getFile?dir=' + _dir, {method: 'get'});
}