Writing on Server

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January 25th, 2001, 04:38 PM

kenowhere

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How can I write information into a file on my server in java servlets?

January 25th, 2001, 06:22 PM

merkinmuffley

film at 11

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Location: Portland, OR

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go to the Java API and look up the java.io package. you write to a file from a servlet the same way you write to a file from any other java code (except applets). i advise using a FileWriter wrapped in a BufferedWriter. good luck. here's another link to the servlet API. the APIs are your best friends. when i have a question about how to implement something, i go there and 90% of the time I find the answer.

January 25th, 2001, 09:37 PM

kenowhere

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I've already tryed a FileWriter wrapped in a BufferOutputStream. I have the following code:

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.net.*;

public class MindmapWWWBoard extends HttpServlet {

String username;
String message;
private Writer out2;

public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
postReceipt(request, out);
}

private void postReceipt(HttpServletRequest request,
PrintWriter out) {
username = request.getParameter("username");
message = request.getParameter("message");
out.println("<html>n" +
"<head>n" +
"<title>n" +
"Your Postn" +
"</title>n" +
"</head>n" +
"<body>n" +
"Username: " + username + " " +
"Message: " + message +
"</body>n" +
"</html>");
try {
FileWriter fw = new FileWriter("mindmap.html", true);
BufferedWriter out2 = new BufferedWriter(fw);
out2.write(message);
out2.flush();
out2.close();
}
catch (IOException e) { }
}
}

Does anyone know why this isn't working? Thanks in advance.

January 26th, 2001, 10:05 AM

merkinmuffley

film at 11

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Location: Portland, OR

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what is the behavior? are there any error messages?

January 26th, 2001, 10:17 AM

kenowhere

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It compiles ok, but when I run it on the server, it doensn't write to the HTML file. It shows the username and message after post.

January 26th, 2001, 12:19 PM

merkinmuffley

film at 11

Join Date: Aug 2000

Location: Portland, OR

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how about this:

Code:

File file = new File("/home/your/path", "mindmap.html");
byte[] fileBuffer;

FileOutputStream outstream;
FileInputStream instream;

int fileLength;
if (file.exists()) fileLength=(int)file.length();
else fileLength=0;

// buffer for your message + file's contents
fileBuffer = new byte[message.length() + fileLength];

// stream in the file to the buffer
if (file.exists()) {
 try {
     inStream = new FileInputStream(file);
     int numRead = 0;
     int counter = 0;
     while (numRead!=-1 && counter<fileLength) {
        numRead = inStream.read(fileBuffer, counter, fileLength-counter);
        counter += numRead;
     }
  }
catch...
}

byte[] messageBytes = message.getBytes();
//add message to the file buffer
for (int j=fileLength; j<fileBuffer.length; j++)
    fileBuffer[j] = messageBytes[j-fileLength];

//shove fileBuffer back into file
try {
    outStream = new FileOutputStream(file);
    outStream.write(fileBuffer);
    outStream.close();
}
catch...

that's bound to have a bug or two but i'm sure you can fix it up.

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