Java Tutorial/Servlet/File Save Read

Материал из Java эксперт
Версия от 17:44, 31 мая 2010; (обсуждение)
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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()));
  }
}