The transfer methods enable us to directly copy the contents of the file system cache to the file on the system. Thus direct channeling restricts the number of context tl required and enhances the overall code performance.
Java HttpURLConnection to download file from an HTTP URL
Now, in the following sections, we will be looking at ways to download files from a URL using third-party libraries instead of core Java functionality components. Now you may be thinking why would we use this when Java has its own set of libraries to handle IO operations. However, Apache Commons IO overcomes the problem of code rewriting and helps avoid writing boilerplate code. In order to start using the Apache Commons IO library, you will need to download the jar files from the official website.
When you are done downloading the jar files, you need to add them to use them. If you are using an Integrated Development Environment IDE such as Eclipseyou will need to add the files to the build path of your project. There is only a single line of code required to download a file, which looks like:. The connection and read timeouts convey the permissible time for which either the connection may stay idle or reading from the URL may stop.
We will use the copy inputStream, fileOS method to download a file into the local system.
How to Download a File from a URL in Java
Check out our hands-on, practical guide to learning Git, with best-practices, industry-accepted standards, and included cheat sheet. Stop Googling Git commands and actually learn it! The function returns the number of bytes copied.Aug 28, · Open connection on the URL object – which would return an HttpURLConnection object if the URL is an HTTP URL. Open the input stream of the opened connection. Create an output stream to save file to disk. Repeatedly read array of bytes from the input stream and write them to the output stream, until the input stream is empty. Aug 21, · There are multiple ways to download a file using Java code. Here are just a few ways of how you can accomplish the task: Java IO. The most easily available and a basic package available for downloading a file from internet using Java code is the Java IO package. Aug 16, · Saving a web page to a file in Java [closed] Ask Question Asked 10 years, 1 month ago. Active 10 years, 1 month ago. Viewed 9k times -4 0. It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current buswisata.cos:
If the value of the variable i is -1, then it indicates that the contents of the file are over 2GB. When the returned value is -1, you can use fiel function copyLarge inputStream, fileOS in place of the copy inputstream, fileOS function to handle this load. Both of these functions buffer the inputstream internally.http - Saving a web page to a file in Java - Stack Overflow
The internal buffer means we do not have to use the BufferedInputStream class to enhance our code performance and helps us avoid writing boilerplate code. Another library managed by the Apache organization is the HttpComponents package. This library uses the request-response mechanism to download the file from a given URL. The first step to downloading a file is to create an HTTP client object that would issue the request to the server.
For this, we will be using the CloseableHttpClient class. The code snippet that creates a new HTTP client is as follows:. We then need to create an HttpGet or HttpPost object to send the request to the server. The request is created by the following line of code:. The execute request function is applied to the client object and returns with a response from the server. Once the request is sent to the server we need a response object to receive the data sent from the server.
To catch the response from the server we use the HttpResponse class object. The data sent by the server in the form of a message is obtained through the getEntity function. You can also obtain the response code sent by the server through the response object and use it to your specific need.
Download webpage in Java
The data to be downloaded is encapsulated within the entity object and can be extracted using the getContent function. The getContent function returns an InputStream object that can be further used with a BufferedInputStreamReader to enhance performance. Now all you need to do is read from the stream byte by byte and write the contents into a file using the FileOutputStream class.
The last thing required to be done is closing all the open resources in order to ensure that the system resources are not overutilized and that there are no memory leaks. So there you have it - these are the simplest ways to download a file using the basic Java code and other third party libraries. Saving a web page to a file in Java [closed] Ask Question. Asked 10 years, 2 months ago. Active 10 years, 2 months ago.
Viewed 9k times. Improve this question. Mike Deck Raj Raj 2 2 gold badges 10 10 silver badges 18 18 bronze badges. What exception are you getting? Might be more helpful if you told us. What exception is it throwing? I bet you do not have the IP of java.
Free eBook: Git Essentials
What is the exception? You need to provide as much information as possible. You are getting an exception, is a very broad statement. Show 7 more comments. Active Oldest Votes. Improve this answer. Mike Deck Mike Deck Please mark Mike's answer correct if it solved the problem.
Improve your dev skills!
Raju Komaturi: why do you insist on using sockets? Using URL is the correct way. Add a comment. You have to be polite to the server and send a request first: socket. Denis Tulskiy Denis Tulskiy