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Difference between revisions of "Main Page"

Line 1: Line 1:
 +
__NOTOC__
 +
+8801713083079
  
 +
1. Download files data from many
 +
URLs and save them to the local
 +
files in the directory of your choice:
 +
 +
This Java program lets you download files from one or more URLs and save them in the directory where you want. This program takes destination directory for the files to save as first command line argument and URLs for the files as next command line arguments separated by space. Java provides URLConnection class that represents a communication link between the application and a URL. Invoking the openConnection method on a URL creates URLConnection object. Now get [[InputStream]] object from that connection and read the data. Finally write the data to the local file.
 +
 +
[[FileDataDownload]].java:
 +
 +
import java.io.*;
 +
import java.net.*;
 +
public class [[FileDataDownload]] {
 +
final static int size=1024;
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public static void
 +
[[FileDownload]](String fileAddress, String
 +
localFileName, String destinationDir) {
 +
[[OutputStream]] os = null;
 +
URLConnection URLConn = null;
 +
 +
// URLConnection class represents a communication link between the
 +
// application and a URL.
 +
 +
[[InputStream]] is = null;
 +
try {
 +
URL fileUrl;
 +
byte[] buf;
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int [[ByteRead]],[[ByteWritten]]=0;
 +
fileUrl= new URL(fileAddress);
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os = new [[BufferedOutputStream]](new
 +
[[FileOutputStream]](destinationDir+”\\”+
 +
localFileName));
 +
//The URLConnection object is
 +
created by invoking the
 +
 +
// openConnection method on a URL.
 +
 +
URLConn = fileUrl.openConnection();
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is = URLConn.getInputStream();
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buf = new byte[size];
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while (([[ByteRead]] = is.read(buf)) != -1) {
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os.write(buf, 0, [[ByteRead]]);
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[[ByteWritten]] += [[ByteRead]];
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}
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System.out.println(“Downloaded
 +
Successfully.”);
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System.out.println(“File name
 +
:\””+localFileName+ “\”\nNo of
 +
bytes :” + [[ByteWritten]]);
 +
}
 +
catch (Exception e) {
 +
e.printStackTrace();
 +
}
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finally {
 +
try {
 +
is.close();
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os.close();
 +
}
 +
catch (IOException e) {
 +
e.printStackTrace();
 +
</nowiki></pre>
 +
public static void fileDownload(String
 +
fileAddress, String destinationDir)
 +
{
 +
 +
// Find the index of last occurance of character ‘/’ and ‘.’.
 +
 +
int lastIndexOfSlash =
 +
fileAddress.lastIndexOf(‘/’);
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int lastIndexOfPeriod =
 +
fileAddress.lastIndexOf(‘.’);
 +
 +
// Find the name of file to be downloaded from the address.
 +
 +
String fileName=fileAddress.substring
 +
(lastIndexOfSlash + 1);
 +
 +
// Check whether path or file name is given correctly.
 +
 +
if (lastIndexOfPeriod >=1 && lastIndexOfSlash >= 0 &&
 +
lastIndexOfSlash < fileAddress.length()
 +
-1 1)
 +
{
 +
[[FileDownload]](fileAddress,fileName,
 +
destinationDir);
 +
}
 +
else
 +
{
 +
System.err.println(“Specify correct path or file name.”);
 +
}}
 +
public static void main(String[] args)
 +
{
 +
 +
// Check whether there are atleast
 +
two arguments.
 +
 +
if(args.length==2)
 +
{
 +
for (int i = 1; i < args.length; i++) {
 +
fileDownload(args[i],args[0]);
 +
}
 +
}
 +
else{System.err.println(“Provide
 +
\”Destination directory path\” and \”file
 +
names\” separated by space.”);
 +
}
 +
}
 +
}
 +
 +
Compile and Run:
 +
 +
In this example, the location for the
 +
directory where file “jsf.htm” is to be
 +
saved is “c:\download”.
 +
 +
C:\[[JavaJazzup]]>javac [[FileDataDownload]].java
 +
C:\[[JavaJazzup]]>java [[FileDataDownload]]
 +
c:\download http://localhost:8080/
 +
tomahawk_tags/pages/jsf.htm

Revision as of 11:32, 19 April 2011

+8801713083079

1. Download files data from many URLs and save them to the local files in the directory of your choice:

This Java program lets you download files from one or more URLs and save them in the directory where you want. This program takes destination directory for the files to save as first command line argument and URLs for the files as next command line arguments separated by space. Java provides URLConnection class that represents a communication link between the application and a URL. Invoking the openConnection method on a URL creates URLConnection object. Now get InputStream object from that connection and read the data. Finally write the data to the local file.

FileDataDownload.java:

import java.io.*; import java.net.*; public class FileDataDownload { final static int size=1024; public static void FileDownload(String fileAddress, String localFileName, String destinationDir) { OutputStream os = null; URLConnection URLConn = null;

// URLConnection class represents a communication link between the // application and a URL.

InputStream is = null; try { URL fileUrl; byte[] buf; int ByteRead,ByteWritten=0; fileUrl= new URL(fileAddress); os = new BufferedOutputStream(new FileOutputStream(destinationDir+”\\”+ localFileName)); //The URLConnection object is created by invoking the

// openConnection method on a URL.

URLConn = fileUrl.openConnection(); is = URLConn.getInputStream(); buf = new byte[size]; while ((ByteRead = is.read(buf)) != -1) { os.write(buf, 0, ByteRead); ByteWritten += ByteRead; } System.out.println(“Downloaded Successfully.”); System.out.println(“File name

\””+localFileName+ “\”\nNo of

bytes :” + ByteWritten); } catch (Exception e) { e.printStackTrace(); } finally { try { is.close(); os.close(); } catch (IOException e) { e.printStackTrace(); </nowiki></pre> 

public static void fileDownload(String

fileAddress, String destinationDir) {

// Find the index of last occurance of character ‘/’ and ‘.’.

int lastIndexOfSlash = fileAddress.lastIndexOf(‘/’); int lastIndexOfPeriod = fileAddress.lastIndexOf(‘.’);

// Find the name of file to be downloaded from the address.

String fileName=fileAddress.substring (lastIndexOfSlash + 1);

// Check whether path or file name is given correctly.

if (lastIndexOfPeriod >=1 && lastIndexOfSlash >= 0 && lastIndexOfSlash < fileAddress.length() -1 1) { FileDownload(fileAddress,fileName, destinationDir); } else { System.err.println(“Specify correct path or file name.”); }} public static void main(String[] args) {

// Check whether there are atleast two arguments.

if(args.length==2) { for (int i = 1; i < args.length; i++) { fileDownload(args[i],args[0]); } } else{System.err.println(“Provide \”Destination directory path\” and \”file names\” separated by space.”); } } }

Compile and Run:

In this example, the location for the directory where file “jsf.htm” is to be saved is “c:\download”.

C:\JavaJazzup>javac FileDataDownload.java C:\JavaJazzup>java FileDataDownload c:\download http://localhost:8080/ tomahawk_tags/pages/jsf.htm

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