Java Tutorial/Servlet/File Save Read
Load File Content and Save it back in a Servlet
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class MyServlet extends HttpServlet {
int count;
public void init() throws ServletException {
FileReader fileReader = null;
BufferedReader bufferedReader = null;
try {
fileReader = new FileReader("InitDestroyCounter.initial");
bufferedReader = new BufferedReader(fileReader);
String initial = bufferedReader.readLine();
count = Integer.parseInt(initial);
bufferedReader.close();
return;
}
catch (Exception ignored) { }
String initial = getInitParameter("initial");
try {
count = Integer.parseInt(initial);
return;
}
catch (NumberFormatException ignored) { } // null or non-integer value
count = 0;
}
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
res.setContentType("text/plain");
PrintWriter out = res.getWriter();
count++;
out.println("Since the beginning, this servlet has been accessed " +
count + " times.");
}
public void destroy() {
super.destroy();
saveState();
}
public void saveState() {
FileWriter fileWriter = null;
PrintWriter printWriter = null;
try {
fileWriter = new FileWriter("InitDestroyCounter.initial");
printWriter = new PrintWriter(fileWriter);
printWriter.println(count);
printWriter.close();
return;
}
catch (IOException e) {
}
}
}
Read File in a Servlet
import java.io.*;
import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
res.setContentType("text/plain; charset=Shift_JIS");
PrintWriter out = res.getWriter();
res.setHeader("Content-Language", "ja");
Locale locale = new Locale("ja", "");
DateFormat full = DateFormat.getDateTimeInstance(DateFormat.LONG,
DateFormat.LONG,
locale);
out.println("In Japanese:");
try {
FileInputStream fis =
new FileInputStream(req.getRealPath("/HelloWorld.ISO-2022-JP"));
InputStreamReader isr = new InputStreamReader(fis, "ISO-2022-JP");
BufferedReader reader = new BufferedReader(isr);
String line = null;
while ((line = reader.readLine()) != null) {
out.println(line);
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
out.println(full.format(new Date()));
}
}