You need to call: ImageIO. Paolo Paolo Hi Paolo, it works.. This may help: stackoverflow. If path is already exists than you will overwrite that file with your image. I think that you want to save your image into some existing folder in HDFS.
In that case you need to write your image to new Path path, "SomeImageName. Aleksei Shestakov Aleksei Shestakov 2, 2 2 gold badges 11 11 silver badges 14 14 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast what if you could invest in your favorite developer?
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. To lower the number of lines of code we can use the Files class available from Java 7. The Files class contains methods that read all the bytes at once and then copies it into another file. Here is how you can use it:. Java NIO is an alternative package to handle networking and input-output operations in Java.
The main advantage that the Java NIO package offers is that it's non-blocking, and has channeling and buffering capabilities. When we use the Java IO library we work with streams that read data byte by byte. However, the Java NIO package uses channels and buffers. The buffering and channeling capabilities allow the system to copy contents from a URL directly into the intended file without needing to save the bytes in application memory, which would be an intermediary step.
The ability to work with channels boosts performance. The downloaded contents will be transferred to a file on the local system via the corresponding file channel. After defining the file channel we will use the transferFrom method to copy the contents read from the readChannel object to the file destination using the writeChannel object.
The transferFrom and transferTo methods are much more efficient than working with streams using a buffer. 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 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:.
I want to upload and download file in hadoop. Ubuntu Community Ask! Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. How to upload and download file in hadoop? Ask Question. Asked 7 years, 8 months ago. Active 6 years, 4 months ago. Viewed 34k times. Improve this question. Add a comment.
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