Beingjavaguys download files

HibernateException: No Session found for current thread at org. Improve this question. Community Bot 1 1 1 silver badge. DragonZoned DragonZoned 2 2 silver badges 14 14 bronze badges. Show your code. Show the complete stack trace of the exception.

Tell us how these two xml files are used. I have added Code above as Update. The impls are implementing interfaces. Added Stack Trace. You're scanning all your classes, instead of just the web-releted classes, in the child mvc context. The beans used are thus instantiated by the child context instead of the root context where the TransactionManager is defined.

I personally prefer using a single context. That makes things simpler. Should I specifically mention the controller and service and Dao instead ,so Domain class is not scanned — DragonZoned. Or should Include one more subpackage and include all COntroller,services and all in it. Perhaps then use the subpackage as base package for scanning. Show 8 more comments. Active Oldest Votes. 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. This context switch is expensive from a performance perspective. When we read a large number of bytes, the application performance will be poor, due to a large number of context switches involved.

For writing the bytes read from the URL to our local file, we'll use the write method from the FileOutputStream class:. When using a BufferedInputStream, the read method will read as many bytes as we set for the buffer size.

In our example, we're already doing this by reading blocks of bytes at a time, so BufferedInputStream isn't necessary. The example above is very verbose, but luckily, as of Java 7, we have the Files class which contains helper methods for handling IO operations. We can use the Files. Our code works well but can be improved. Its main drawback is the fact that the bytes are buffered into memory. Fortunately, Java offers us the NIO package that has methods to transfer bytes directly between 2 Channels without buffering.

The Java NIO package offers the possibility to transfer bytes between 2 Channels without buffering them into the application memory. The bytes read from the ReadableByteChannel will be transferred to a FileChannel corresponding to the file that will be downloaded:. The transferTo and transferFrom methods are more efficient than simply reading from a stream using a buffer.

Depending on the underlying operating system, the data can be transferred directly from the filesystem cache to our file without copying any bytes into the application memory. On Linux and UNIX systems, these methods use the zero-copy technique that reduces the number of context switches between the kernel mode and user mode.

We've seen in the examples above how we can download content from a URL just by using the Java core functionality. We also can leverage the functionality of existing libraries to ease our work, when performance tweaks aren't needed. We could wrap all the logic into a Callable , or we could use an existing library for this. 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.