Setting up a Spring Boot project with Apache POI dependencies and other necessary dependencies poi 4.1.2 poi-ooxml 4.1.2 Ĭreating an API endpoint to receive a HTTP request to download the Excel file = RequestMethod. Sending API response as a data byte array with relevant header details of openxmlformats as the MediaType Extensive working experience in developing web applications using HTML5, CSS3, AJAX, jQuery, JavaScript, Angular, React, Bootstrap, Java, and Spring Framework.Fetching the list of POJO class objects and passing to the writer and get the response as an byte array.Implementing the generic Xlsx writer with dynamic class reflection and POI spreadsheet data population into the workbook.Use reflection to modify any class/object field. This package provides objects that can be used to list any fields inside a class, invoke any class methods or access and modify any fields, and when I say any I mean all of them, even private ones. And setting up a POJO class to hold metadata for each field of the above class. Reflection is a direct part of the Java language. Defining the Java POJO class which will be used to write into the Excel sheet.Defining the Java Annotation interfaces which will be used for the dynamic class reflection.I enjoy hiking, running, and most sports. Creating an API endpoint to send an HTTP request to download the Excel file. Passionate Software Engineer exploring to learn and share knowledge.Setting up a Spring Boot project with Apache POI dependencies and other necessary dependencies.These main steps will be followed for the implementation : When I still wrote the project according to my previous coding habits, the project did not start successfully. The figure below shows the Apache POI related interfaces and classes for manipulating xlsx Excel files.įurthermore it provides excellent support for additional excel features such as working with Formulas, creating cell styles by filling colors and borders, fonts, headers and footers, data validations, images, hyperlinks etc. Recently, we have a new project using Spring Boot 2.6. The XSSF library contains the classes for handling the xlsx Excel format. XSSF (XML Spreadsheet Format) − It is used for xlsx file format of MS-Excel (2007 and later) files.Įach of the Apache POI libraries are dedicated to manipulate each particular type of file. HSSF (Horrible Spreadsheet Format) − It is used for xlsx file format of MS-Excel (97–2007) files. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview Questions. There are fundamental reasons to do things via Reflection: 1) test non-public methods (not recommended, though), and 2) inaccessible instance variables (to mock). This post shows how to get and set instance variables and invoke methods via the Reflection API using Spring ReflectionTestUtils. Since we are focusing on writing Excel files, we will be using the following file formats of Apache POI for spreadsheets. Easy Reflection using Spring ReflectionTestUtils. The objective of Apache POI is to design a cross-platform API that can manipulate various file formats of Microsoft Office and Open Office Documents. A simple example using Java Reflection to read and XML file, create a class of students using reflection (methods and field calls), add students to classes. The Java reflection class are in package java.lang. For example mapping object values at runtime. Its very powerful, and can be used to perform different operations at runtime. The need for custom code for writing each type of fields and row-column processing has been reduced, you are good to go with minimum customization.Īpache POI (Poor Obfuscation Implementation) is a popular open source library run by the Apache Software Foundation which is developed for reading and writing files in Microsoft Office formats, such as Word, PowerPoint, and Excel. Java Reflection is used by Java Programs to inspect and modify the runtime behavior of applications running in the Java virtual machine. There are three steps that must be followed to use these classes. You can build your code starting from there List all subpackages of a package (when their classes are loaded dynamically) Almost certainly the best way to deal with this is to create a list as a build step (probably as a. And, using the object we can call various methods to get information about. The reflection classes, such as Method, are found in . You should use java Reflection This link offers a tutorial that cover all the thing you can do using Reflection. Java reflection class with methods tutorial : The provides the methods to examine the runtime properties of the object including its members. In this article, a way to generalize the writing to an Excel file for any type of Objects with both single and composite(array) types of fields has been achieved using Apache POI with the support of Java Reflection feature. In order to reflect a Java class, we first need to create an object of Class. Working with Excel documents is a frequently used feature in a software application.
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