Choosing a file download java

But I don't know how to write one servlet which will decide which file to send to the client. This has to happen on clicking of a link, so I can't send parameters which can help me determine which file to download. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 6 years, 9 months ago.

Active 6 years, 9 months ago. Viewed times. You can customize this file view by creating a custom subclass of FileView and using an instance of the class as an argument to the setFileView method. The example uses an instance of a custom class, implemented in ImageFileView. The ImageFileView class shows a different icon for each type of image accepted by the image filter described previously.

The customized file chooser in FileChooserDemo2 has an accessory component. Otherwise, the accessory component is empty. Aside from a previewer, probably the most common use for the accessory component is a panel with more controls on it such as check boxes that toggle between features. The example calls the setAccessory method to establish an instance of the ImagePreview class, implemented in ImagePreview.

Any object that inherits from the JComponent class can be an accessory component. The component should have a preferred size that looks good in the file chooser. The file chooser fires a property change event when the user selects an item in the list. A program with an accessory component must register to receive these events to update the accessory component whenever the selection changes.

In the example, the ImagePreview object itself registers for these events. This keeps all the code related to the accessory component together in one class. Here is the example's implementation of the propertyChange method, which is the method called when a property change event is fired:. The loadImage and repaint methods use the File object to load the image and repaint the accessory component.

This table shows the examples that use file choosers and points to where those examples are described. All rights reserved. Hide TOC. Using Swing Components. Try this: Compile and run the example, consult the example index. Click the Open a File button. Navigate around the file chooser, choose a file, and click the dialog's Open button.

Use the Save a File button to bring up a save dialog. Try to use all of the controls on the file chooser. In the source file FileChooserDemo. Change Language. Related Articles. Table of Contents. Improve Article. Save Article. Like Article. Last Updated : 14 Apr, Worry not, in this article I'll explain the building blocks needed in order to automate downloading files for these kinds of tasks.

Before you can create an application to download and create datasets for you, you'll need to know the basics required for automating file downloads via Java code. Getting the basics right will help you use them to your own specific set of needs, whether it's for a backend server application or Android app. There are multiple ways to download a file using Java code. Here are just a few ways of how you can accomplish the task:. The most easily available and a basic package available for downloading a file from internet using Java code is the Java IO package.

Here we will be using the BufferedInputStream and the URL classes to open and read a file on a given address to a file on our local system. The reason we use the BufferedInputStream class instead of the InputStream is its buffering ability that gives our code a performance boost. Before we dive deeper into the coding aspect let's take an overview of the classes and the individual functions we will be using in the process.

The java. URL class in Java is a built-in library that offers multiple methods to access and manipulate data on the internet. In this case, we will be using the openStream function of the URL class. The method signature for the openStream function is:. The openStream function works on an object of the URL class. The URL class opens up a connection to the given URL and the openStream method returns an input stream which is used to read data from the connection. These classes are used for reading from a file and writing to it, respectively.

The contents are read as bytes and copied to a file in the local directory using the FileOutputStream.