| Character | Meaning |
|---|---|
| . | Match any single character |
| * | Match zero or more of any character |
| ^ | Anchor at beginning of line (^dog only matches dog at the beginning of a line) |
| $ | Anchor at end of line (dog$ only matches dog at the end of a line) |
| \ | Take the following special character literally (\. matches a period) |
| [...] | Match a single position to anything between the brackets. For example "d[io]g" matches to both "dig" and "dog" |
| [^...] | Match a single position to anything that is not between the brackets. For example "d[^io]g" would not match "dig" or "dog" but would match "dug". |
| \(...\) | In a regular expression, these marks are used to save parts of
the matched text for use in a substitute operation. Up to nine of these pairs can appear in a regular expression, and in a substitution pattern these can be referenced as \1 through \9. |
| \<...\> | Use these delimiters to indicate that whatever is in between them must exist as a word in order to be matched. This means that it must have either white space or punctuation on either side of it. |
import java.util.regex.*;
final static String EXPR = "http://([0-9a-zA-Z./@~?&=_-]+)|([_0-9a-zA-Z-]+(\\.[_0-9a-zA-Z-]+)*)@([0-9a-zA-Z-]+(\\.[0-9a-zA-Z-]+)*)|<|>|\\|\r|\n"; // http or email
/**
* handle body text
*/
public String handleBodyText(String data) {
StringBuffer buffer = new StringBuffer(data.length() + 30);
Matcher matcher = Pattern.compile(EXPR).matcher(data);
int count = 0;
while (matcher.find()) {
count++;
String group = matcher.group();
if (group.startsWith("http://")) { // http address
// $# indicates group tokens and $0 always indicates the whole matched string
matcher.appendReplacement(buffer, "<a href=\"$0\" target=\"_blank\">$0</A>");
} else {
switch (group.charAt(0)) {
case '<' :
matcher.appendReplacement(buffer, "%26lt;");
break;
case '>' :
matcher.appendReplacement(buffer, "%26gt;");
break;
case '\\' :
matcher.appendReplacement(buffer, "%5c");
break;
case '\r' :
matcher.appendReplacement(buffer, "<br>");
break;
case '\n' :
matcher.appendReplacement(buffer, "<br>");
break;
default : // email address
matcher.appendReplacement(buffer, "<a href=\"mailto:$0\">$0</A>");
break;
}
}
}
if (count > 0) {
matcher.appendTail(buffer);
return buffer.toString();
}
return data;
}