Thus direct channeling restricts the number of context switches required and enhances the overall code performance. 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 Eclipse , you 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. 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. 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 the function copyLarge inputStream, fileOS in place of the copy inputstream, fileOS function to handle this load.
Both of these functions buffer the inputstream internally. 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. Asked 11 years, 6 months ago. Active 2 years, 9 months ago. Viewed 70k times. Improve this question. Ankur Ankur Add a comment. Active Oldest Votes. So, I assume you just want to know what extension a file has based on it's URI even though this isn't completely trustworthy; You can get the extension from any URI, URL or file path using the method bellow.
Two examples might be: Validate the URI by checking it exists, or by making sure the syntax of the URI is valid, possibly using a regular expression. Trim the extension to remove unwanted white spaces. Hope this helps! Improve this answer. This won't work if the url has a question mark after the filename or a hash. That period character check you added doesn't do anything very useful, since there's a period before the top level domain anyway. If uri doesn't contain period character can I assume that uri is NOT a uri of a file?
AndroidDeveloper, no. Take the following url as an example. Uri is different than Url — Ali Rezaiyan. This will avoid returning null values on file name with spaces and special characters.
Community Bot 1 1 1 silver badge. Aaron Aaron 1, 10 10 silver badges 16 16 bronze badges. There are two answers to this. Stephen C Stephen C k 90 90 gold badges silver badges bronze badges. Well yea. But if there is not internet, you can't fetch the file. So it hardly matters what its type is. And you can wait until the internet comes back, or "guess based on the extension" if you really need to "know" now. Maybe you just need to know the extension without fetching the file?
If the extension is not in the URI, AND you can't fetch the file or its metadata to find out what the file type really is, then there is no solution Joop Eggen Joop Eggen 2 2 silver badges 3 3 bronze badges. Append Text to an Existing File. Convert File to byte array and Vice-Versa. Create Directories. Get all Files Present in a Directory. Related Topics Java File Class. Java String lastIndexOf.
Java String substring. Since all file extension starts with '. Example 2: Get the file extension of all files present in a directory.
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