Introduction
In this program we will show you about the concept of the reading file from an applet. This
program illustrates you how an applet can read the content from the given file. In this program
we passes the file name as applet parameter which is then read by the applet program.
If you specify the file name( which has to be read ) in the html file then the
program will read the file otherwise applet will read the specified file for
the String type variable named fileToRead.
There are two functions have been used in the program. One is init()
which is
the first step of the life cycle for an applet in which you can initialize or set
anything to start for the applet. The function init()
initiates some variables, arrange
objects in a applet like text area, and receive the file name in fileToRead
variable
from html file and calls the function readFile()
that is the another
function has been used. First of all readFile() function
retrieve the path of the
file to be read by the created object url
from the URL
class which is importing using the statement import
java.net.*; package. The
url object retrieves the file using getCodeBase()
pattern which returns the parent of the html file
the applet is embedded in, not the URL
of the applet itself. And then the
function readFile() creates a instance of the StringBuffer
to store the file content. Finally program prints the buffered
string in the text area which will be seen in the applet on the web browser or applet viewer.
Full running Read File Example code is given below:
Here is the code of the program :
import java.applet.*;
import java.awt.*;
import java.io.*;
import java.net.*;
public class readFileApplet extends Applet{
String fileToRead = "test1.txt";
StringBuffer strBuff;
TextArea txtArea;
Graphics g;
public void init(){
txtArea = new TextArea(100, 100);
txtArea.setEditable(false);
add(txtArea, "center");
String prHtml = this.getParameter("fileToRead");
if (prHtml != null) fileToRead = new String(prHtml);
readFile();
}
public void readFile(){
String line;
URL url = null;
try{
url = new URL(getCodeBase(), fileToRead);
}
catch(MalformedURLException e){}
try{
InputStream in = url.openStream();
BufferedReader bf = new BufferedReader(new InputStreamReader(in));
strBuff = new StringBuffer();
while((line = bf.readLine()) != null){
strBuff.append(line + "\n");
}
txtArea.append("File Name : " + fileToRead + "\n");
txtArea.append(strBuff.toString());
}
catch(IOException e){
e.printStackTrace();
}
}
}
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