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package javax.activation;
import java.util.
Hashtable;
import java.util.
Enumeration;
import java.util.
Locale;
/**
* A parameter list of a MimeType
* as defined in RFC 2045 and 2046. The Primary type of the
* object must already be stripped off.
*
* @see javax.activation.MimeType
*/
public class
MimeTypeParameterList {
private
Hashtable parameters;
/**
* A string that holds all the special chars.
*/
private static final
String TSPECIALS = "()<>@,;:/[]?=\\\"";
/**
* Default constructor.
*/
public
MimeTypeParameterList() {
parameters = new
Hashtable();
}
/**
* Constructs a new MimeTypeParameterList with the passed in data.
*
* @param parameterList an RFC 2045, 2046 compliant parameter list.
* @exception MimeTypeParseException if the MIME type can't be parsed
*/
public
MimeTypeParameterList(
String parameterList)
throws
MimeTypeParseException {
parameters = new
Hashtable();
// now parse rawdata
parse(
parameterList);
}
/**
* A routine for parsing the parameter list out of a String.
*
* @param parameterList an RFC 2045, 2046 compliant parameter list.
* @exception MimeTypeParseException if the MIME type can't be parsed
*/
protected void
parse(
String parameterList) throws
MimeTypeParseException {
if (
parameterList == null)
return;
int
length =
parameterList.
length();
if (
length <= 0)
return;
int
i;
char
c;
for (
i =
skipWhiteSpace(
parameterList, 0);
i <
length && (
c =
parameterList.
charAt(
i)) == ';';
i =
skipWhiteSpace(
parameterList,
i)) {
int
lastIndex;
String name;
String value;
// eat the ';'
i++;
// now parse the parameter name
// skip whitespace
i =
skipWhiteSpace(
parameterList,
i);
// tolerate trailing semicolon, even though it violates the spec
if (
i >=
length)
return;
// find the end of the token char run
lastIndex =
i;
while ((
i <
length) &&
isTokenChar(
parameterList.
charAt(
i)))
i++;
name =
parameterList.
substring(
lastIndex,
i).
toLowerCase(
Locale.
ENGLISH);
// now parse the '=' that separates the name from the value
i =
skipWhiteSpace(
parameterList,
i);
if (
i >=
length ||
parameterList.
charAt(
i) != '=')
throw new
MimeTypeParseException(
"Couldn't find the '=' that separates a " +
"parameter name from its value.");
// eat it and parse the parameter value
i++;
i =
skipWhiteSpace(
parameterList,
i);
if (
i >=
length)
throw new
MimeTypeParseException(
"Couldn't find a value for parameter named " +
name);
// now find out whether or not we have a quoted value
c =
parameterList.
charAt(
i);
if (
c == '"') {
// yup it's quoted so eat it and capture the quoted string
i++;
if (
i >=
length)
throw new
MimeTypeParseException(
"Encountered unterminated quoted parameter value.");
lastIndex =
i;
// find the next unescaped quote
while (
i <
length) {
c =
parameterList.
charAt(
i);
if (
c == '"')
break;
if (
c == '\\') {
// found an escape sequence
// so skip this and the
// next character
i++;
}
i++;
}
if (
c != '"')
throw new
MimeTypeParseException(
"Encountered unterminated quoted parameter value.");
value =
unquote(
parameterList.
substring(
lastIndex,
i));
// eat the quote
i++;
} else if (
isTokenChar(
c)) {
// nope it's an ordinary token so it
// ends with a non-token char
lastIndex =
i;
while (
i <
length &&
isTokenChar(
parameterList.
charAt(
i)))
i++;
value =
parameterList.
substring(
lastIndex,
i);
} else {
// it ain't a value
throw new
MimeTypeParseException(
"Unexpected character encountered at index " +
i);
}
// now put the data into the hashtable
parameters.
put(
name,
value);
}
if (
i <
length) {
throw new
MimeTypeParseException(
"More characters encountered in input than expected.");
}
}
/**
* Return the number of name-value pairs in this list.
*
* @return the number of parameters
*/
public int
size() {
return
parameters.
size();
}
/**
* Determine whether or not this list is empty.
*
* @return true if there are no parameters
*/
public boolean
isEmpty() {
return
parameters.
isEmpty();
}
/**
* Retrieve the value associated with the given name, or null if there
* is no current association.
*
* @param name the parameter name
* @return the parameter's value
*/
public
String get(
String name) {
return (
String)
parameters.
get(
name.
trim().
toLowerCase(
Locale.
ENGLISH));
}
/**
* Set the value to be associated with the given name, replacing
* any previous association.
*
* @param name the parameter name
* @param value the parameter's value
*/
public void
set(
String name,
String value) {
parameters.
put(
name.
trim().
toLowerCase(
Locale.
ENGLISH),
value);
}
/**
* Remove any value associated with the given name.
*
* @param name the parameter name
*/
public void
remove(
String name) {
parameters.
remove(
name.
trim().
toLowerCase(
Locale.
ENGLISH));
}
/**
* Retrieve an enumeration of all the names in this list.
*
* @return an enumeration of all parameter names
*/
public
Enumeration getNames() {
return
parameters.
keys();
}
/**
* Return a string representation of this object.
*/
public
String toString() {
StringBuffer buffer = new
StringBuffer();
buffer.
ensureCapacity(
parameters.
size() * 16);
// heuristic: 8 characters per field
Enumeration keys =
parameters.
keys();
while (
keys.
hasMoreElements()) {
String key = (
String)
keys.
nextElement();
buffer.
append("; ");
buffer.
append(
key);
buffer.
append('=');
buffer.
append(
quote((
String)
parameters.
get(
key)));
}
return
buffer.
toString();
}
// below here be scary parsing related things
/**
* Determine whether or not a given character belongs to a legal token.
*/
private static boolean
isTokenChar(char
c) {
return ((
c > 040) && (
c < 0177)) && (
TSPECIALS.
indexOf(
c) < 0);
}
/**
* return the index of the first non white space character in
* rawdata at or after index i.
*/
private static int
skipWhiteSpace(
String rawdata, int
i) {
int
length =
rawdata.
length();
while ((
i <
length) &&
Character.
isWhitespace(
rawdata.
charAt(
i)))
i++;
return
i;
}
/**
* A routine that knows how and when to quote and escape the given value.
*/
private static
String quote(
String value) {
boolean
needsQuotes = false;
// check to see if we actually have to quote this thing
int
length =
value.
length();
for (int
i = 0; (
i <
length) && !
needsQuotes;
i++) {
needsQuotes = !
isTokenChar(
value.
charAt(
i));
}
if (
needsQuotes) {
StringBuffer buffer = new
StringBuffer();
buffer.
ensureCapacity((int)(
length * 1.5));
// add the initial quote
buffer.
append('"');
// add the properly escaped text
for (int
i = 0;
i <
length; ++
i) {
char
c =
value.
charAt(
i);
if ((
c == '\\') || (
c == '"'))
buffer.
append('\\');
buffer.
append(
c);
}
// add the closing quote
buffer.
append('"');
return
buffer.
toString();
} else {
return
value;
}
}
/**
* A routine that knows how to strip the quotes and
* escape sequences from the given value.
*/
private static
String unquote(
String value) {
int
valueLength =
value.
length();
StringBuffer buffer = new
StringBuffer();
buffer.
ensureCapacity(
valueLength);
boolean
escaped = false;
for (int
i = 0;
i <
valueLength; ++
i) {
char
currentChar =
value.
charAt(
i);
if (!
escaped && (
currentChar != '\\')) {
buffer.
append(
currentChar);
} else if (
escaped) {
buffer.
append(
currentChar);
escaped = false;
} else {
escaped = true;
}
}
return
buffer.
toString();
}
}