Getting the 'from' address from a received email

Question

I am trying to pull the email address indicating who an email address is from, from email that I receive. Then I want to list the 'from' addresses in a separate data file.
How can I code this is Java?

Answer 1

public class ReadEmail {
     String from;
     String to;
     String subject;
     HashMap spam;
     public ReadEmail (String name) {
          String aline;
          int pos;
PrintWriter spam_from;
//PrintWriter ham_from;
          spam = new HashMap();
          try {
spam_from = new PrintWriter(new FileWriter("spam_from.txt"));
BufferedReader fin = new BufferedReader (new FileReader(name));
               while ((aline = fin.readLine()) != null) {
                    if (aline.startsWith("From:")) {
                         pos = aline.indexOf ("From:");
                         from = aline.substring (pos + 6);
                         from = from.trim();
int posat, st, fi;
posat = from.indexOf("@");
char ch;
if(posat != -1) {
// we have an email address
st = posat - 1;
while(st >= 0) {
ch = from.charAt(st);
if((ch >= '0' && ch <= '9') ||
(ch >= 'a' && ch <= 'z') ||
(ch >= 'A' && ch <= 'Z') ||
ch == '.' || ch == '_') {
st--;
else break;
} // end of while
fi = posat + 1;
while(fi < from.length()) {
ch = from.charAt(st);
if((ch >= '0' && ch <= '9') ||
(ch >= 'a' && ch <= 'z') ||
(ch >= 'A' && ch <= 'Z') ||
ch == '.' || ch == '_') {
st++;
else break;
} // end of while
// pull out email address
String email = from.substring(st, fi);
System.out.println(email);
// put it in file
spam_from.println(email);
}// end of if
                         System.out.println (from);
                    if (aline.startsWith("To:")) {
                         pos = aline.indexOf ("To:");
                         to = aline.substring (pos + 3);
                         to = to.trim();
                         System.out.println (to);
                    if (aline.startsWith("Subject:")) {
                         pos = aline.indexOf ("Subject:");
                         subject = aline.substring (pos + 8);
                         subject = subject.trim();
                         System.out.println (subject);
          fin.close();
spam_from.close();
     catch (Exception ex) {
          System.out.println (ex.getMessage());
This code alrady:
Pull Headers out:
-�From� ( I want to only accept incoming mail from those addresses present in the address book.)
-�To� (incoming emails which have been sent to multiple users will be rejected.
-�Subject�
Pull Body out:
-Break up string into pieces (a tokeniser does this)
-Individual words are taken.
-Each word is kept account of in a dictionary.
-If Spam contains a key word, we know it is Spam
-Else; ask dave about line 45 onwards!
-A HashMap is something you can put words in. If the word is already there, increment it, if not, put it in.
-Add up how many times a word is read. When in training mode, we can work out word frequency.
Now I'm trying to pull all the 'from' addresses into a separate data file.
Pls help!