How to write records from a resultset into a txt file ???

Question

Hi, I am a newbie in java servlet technology. Currently, I am having a problem regarding how to write all my records from within a resultset into a text file.
First, I put all my records into a string variable and then append the string into a stringbuffer. After that, I create a bufferoutputstream and used the write method to write into a text file. Below are the code I used in my program.
Connection connection = null;
Statement statement = null;
ResultSet resultset = null;
// Connect to database
connection = getConnection();
StringBuffer str_buf = new StringBuffer();
statement = connection.createStatement();
resultset = statement.executeQuery("SELECT * FROM STUDENT");
String data_row = "";
str_buf.append("STUDENT_ID,NAME,PHONE,ADDRESS,RESULT");
while (resultset.next()) {
   data_row = "\n";
   data_row += resultset.getLong("STUDENT_ID");
   data_row += ",\"" + resultset.getString("NAME").trim() + "\"";
   data_row += ",\"" + resultset.getString("PHONE").trim() + "\"";
   data_row += ",\"" + resultset.getString("ADDRESS").trim() + "\"";
   data_row += ",\"" + resultset.getString("RESULT").trim() + "\"";
   str_buf.append(data_row);
BufferedOutputStream buf_out = null;
// Create a folder and write all records into info.txt
String fileName = "student/info.txt";
buf_out = new BufferedOutputStream(new FileOutputStream(fileName));
int str_len     = str_buf.length();
for (int i = 0; i < str_len; i++) {
   buf_out.write(str_buf.charAt(i));
}So. is this a proper way to write information into a text file ?
The total records are around 150 000. Now, I get an exception which is "XServletError : System.lang.outofmemory". It happen if the total records are more than 60 000, within a while loop when I try to append a string into a stringbuffer.
How should I deal with this kind of situation?
Thanks in advanced and any advice is appreciated. Example is even better to improve understanding.
Thanks

Answer 1

Connection connection = null;
Statement statement = null;
ResultSet resultset = null;
// Connect to database
connection = getConnection();
StringBuffer str_buf = new StringBuffer();
String fileName = "student/info.txt";
FileWriter fw = new FileWriter(fileName);
statement = connection.createStatement();
resultset = statement.executeQuery("SELECT * FROM
STUDENT");
String data_row = "";
fw.write("STUDENT_ID,NAME,PHONE,ADDRESS,RESULT");
while (resultset.next()) {
data_row = "\n";
data_row += resultset.getLong("STUDENT_ID");
data_row += ",\"" + resultset.getString("NAME").trim()
+ "\"";
data_row += ",\"" +
resultset.getString("PHONE").trim() + "\"";
data_row += ",\"" +
resultset.getString("ADDRESS").trim() + "\"";
data_row += ",\"" +
resultset.getString("RESULT").trim() + "\"";
fw.write(data_row);
fw.close();