There is no point in re-inventing the wheels.
When you use Maven or Gradle for dependency management, then it will automatically download these libraries, including the libraries they depend, known as the transitive dependency. For example, if you download Spring Framework then it will also download all other JARs on which Spring is dependent e.g. Log4j etc. You might not realize but having the right version of dependent JARs is a big headache. If you have wrong versions of the JAR then you will get ClassNotFoundException or NoClassDefFoundError, or UnsupportedClassVersionError.
Here is the collection of some of the useful third-party libraries Java developers can use in their application to do a lot of useful tasks. In order to use these libraries, Java developer should also be familiar with that.
1. Logging libraries
Logging libraries are very common because you need them in every project. They are the most important thing for server-side application because logs are only placed where you can see what's going on your application. Even though JDK ships with its own logging library, there are many better alternatives are available e.g. Log4j, SLF4j, and LogBack.
In today's world of web services and internet of things (IoT), JSON has become the go-to protocol to carry information from client to server. They have replaced the XML as the most preferred way to transfer information in a platform-independent way. Unfortunately JDK doesn't have a JSON library yet but fortunately, there are many good third-party libraries which allows you to both parse and create JSON messages e.g. Jackson and Gson.
3. Unit testing libraries
Unit testing is the single most important thing which separates an average developer from a good developer. Programmers often are given excuses for not writing unit tests but the most common excuse for avoiding unit testing is lack of experience and knowledge of popular unit testing library e.g. JUnit, Mockito, and PowerMock.
There is a couple of very good general purpose, third-party library available to Java developer e.g. Apache Commons and Google Guava. These libraries always simplify a lot of tasks.
JDK 9 brought support for HTTP 2.0 and HTTP connection can be made easily using classes in java.net package as well as popular HTTP client libraries e.g. HttpClient and HttpCore.
There are many XML parsing libraries exists e.g. Xerces, JAXB, JAXP, Dom4j, Xstream etc. Xerces2 is the next generation of high performance, fully compliant XML parsers in the Apache Xerces family. This new version of Xerces introduces the Xerces Native Interface (XNI), a complete framework for building parser components and configurations that is extremely modular and easy to program. The Apache Xerces2 parser is the reference implementation of XNI but other parser components, configurations, and parsers can be written using the Xerces Native Interface. Dom4j is another flexible XML framework for Java application.
Believe it or not but all real-world application has to interact with Microsoft office in some form or other. Many application needs to provide functionality to export data in Excel and if you have to do same from your Java application then you need Apache POI API.
If you are writing framework or libraries which generate code or interact with bytecodes then you need a bytecode library. They allow you to read and modify bytecode generated by an application. Some of the popular bytecode libraries in Java world are javassist and Cglib Nodep. The Javassist (JAVA programming ASSISTant) makes Java bytecode manipulation very simple. It is a class library for editing bytecodes in Java. ASM is another useful bytecode editing library.
9. Database connection pool libraries
If you are interacting with the database from Java application but not using database connection pool libraries then you are missing something. Since creating connections at runtime takes time and makes request processing slower, its always advised to use DB connection libraries. Some of the popular ones are Commons Pool and JDBC. In a web application, it's web server which generally provides these functionalities but in core Java application you need to include these connection pool libraries into your classpath to use database connection pool.
Similar to logging and database connection, messaging is also a common feature of many real-world Java application. Java provides JMS, Java Messaging Service but that's not part of JDK and you need to include separate jms.jar. Similarly, if you are using third-party messaging protocol e.g. Tibco RV then you need to use a third-party JAR like tibrv.jar in your application classpath.
Similar to Microsoft Excel and World, PDF is another ubiquitous format. If you need to support PDF functionality in your application e.g. exporting data in PDF files then you can use the iText and Apache FOP libraries. Both provide useful PDF related functionality but iText is richer and better and I always preferred that one. See here to learn more about iText.
Before Java 8, JDK's data and time libraries have so many flaws e.g they were not thread-safe, immutable, and error-prone and many Java developer relied on JodaTime for implementing their date and time requirement. From JDK 8, there is no reason to use Joda because you get all that functionality in the JDK 8's new Date and Time API itself.
13. Collection libraries
Even though JDK has a rich collection libraries, there are are some 3rd party libraries which provide more options e.g. Apache Commons Collections, Goldman Sachs collections, Google Collections, and Trove. The Trove library is particularly useful because it provides high speed regular and primitive collections for Java. FastUtil is another similar API, it extends the Java Collections Framework by providing type-specific maps, sets, lists and priority queues with a small memory footprint and fast access and insertion; provides also big (64-bit) arrays, sets, and lists, and fast, practical I/O classes for binary and text files.
14. Email APIs
The javax.mail and Apache Commons Email - provide an API for sending an email. It is built on top of the JavaMail API, which it aims to simplify.
Similar to JSON and XML, HMTL is another common format many of us have to deal with. Thankfully, we have jsoup which greatly simplify working with HTML in Java application. You can use JSoup to not only parse HTML but also to create HTML documents. It provides a very convenient API for extracting and manipulating data, using the best of DOM, CSS, and jquery-like methods. jsoup implements the WHATWG HTML5 specification and parses HTML to the same DOM as modern browsers do.
The Apache Commons Codec package contains simple encoder and decoders for various formats such as Base64 and Hexadecimal. In addition to these widely used encoders and decoders, the codec package also maintains a collection of phonetic encoding utilities.
H2 is a in-memory database, which you can embed in your Java application. They are great for testing your SQL scripts and running Unit tests which need a database. Apart from this, H2 is not the only DB, you also have Apache Derby and HSQL to choose from.
There are some good JDBC Extension libraries exists which makes debugging easier e.g. P6spy. It is a library which enables database data to be seamlessly intercepted and logged with no code changes to the application. You can use these to log SQL queries and their timings. For example, if you are using PreparedStatment and CallableStatement in your code then these libraries can log an exact call with parameters and how much time it took to execute.
Google Protocol Buffer Protocol Buffers are a way of encoding structured data in an efficient yet extensible format. It's richer and better alternative to Java serialization and I strongly recommend experienced Java developer to learn Google Protobuf.
Some of the useful networking libraries are Netty and Apache MINA. If you are writing an application where you need to do low-level networking task, consider using these libraries.
No comments:
Post a Comment