Archive for the ‘java snippets’ Category

Java comes by default with some classes to manipulate images. Those classes are located in java.awt package and are intended to be used for awt applications. For this reason they are not too rich in functionality to have enough options to control the resize quality. In the following snippet BufferedImage and ImageIO can be used [...]

In the following snippet you can find out how to use the InetAddress class to obtain the ip of the server where a domain is hosted along with the DNS information. Using this class you’ll obtain only the technical DNS details(name server, SOA & MX records), not the emails or the names of the domain [...]

There are 2 useful classes in java to manipulate dates: java.util.Date and java.util.Calendar. Another useful class to format and parse string dates is java.text.SimpleDateFormat.

When you have to deal with a large amount of data to be operated on mySQL databases, the performance can be dramatically improved using a few simple tweaks. First of all you have to use Statement.addBatch/executeBatch instead of simple execute methods. For each added batch, the jdbc driver will store in local memory and when [...]

How To Download a File in Java

Here is a snippet that shows how to download a file in java. The snippet is tested and works just fine: static public void download(String address, String localFileName) throws MalformedURLException , FileNotFoundException , IOException { URL url = new URL(address); OutputStream out = new BufferedOutputStream( new FileOutputStream(localFileName)); URLConnection conn = url.openConnection(); InputStream in = conn.getInputStream(); [...]

HttpClient is an apache java library that can be used to read pages over http. It can be used mainly for webpages and provide a well defined API that can handle Cookies, Sessions,… It offers support for both Get and Post methods, so it’s very useful for writing http java clients that can login and [...]

Sometimes I feel there are too many classes in java to work with streams and files. InputStream is the base class of all the classes in Java IO API. The input stream class is intended to be used to read the data from different sources in chunks. This is useful for large streams that don’t [...]

There are two options to store parameters in web.xml: – context parameters – available to the entire scope of the web application – init parameters – available in the context of a servlet or filter in the web application Context Parameters

Java properties files are just simple text files that are widely used in Java to store different properties which should not be hard coded in java source files. By convention, properties files should have the .properties extension. They have a simple structure, each line defining a key/value pair. It is also possible to define larger [...]

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