Spring Boot Apache Poi Read Excel File?

Spring Boot Apache Poi Read Excel File
Apache POI – API Basics to Read/Write Excel Files – The Apache POI library is capable to read and write both XLS and XLSX file formats of Excel. HSSF implementation is provided by the POI to read/write the XLS file. XSSF implementation is provided to read/write the XLSX file.

  • POI library provides various classes and interfaces for reading and writing Excel files.
  • Let’s see the basic interfaces and classes here: The basic interfaces are Workbook, Sheet, Row, Cell, CellStyle, Font, etc.
  • And there are specific concrete classes for specific file formats (.xls and,xlsx).

For Excel file format 2003 (XLS): HSSFWorkbook, HSSFSheet, HSSFRow, HSSFCell, etc. For Excel file format 2007 (XLSX): XSSFWorkbook, XSSFSheet, XSSFRow, XSSFCell, etc.

  • HSSFWorkbook & XSSFWorkbook – used to create the workbook
  • HSSFSheet & XSSFSheet – used to create the sheet for the excel file
  • HSSFRow & XSSFRow – used to create the row in the sheet
  • HSSFCell & XSSFCell – used to create the cell in the row

We recommend you use common interfaces to support both Excel format XLS and XLSX.
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What is Apache POI in Java?

1. Getting Apache POI library – Apache POI is the pure Java API for reading and writing Excel files in both formats XLS (Excel 2003 and earlier) and XLSX (Excel 2007 and later). To use Apache POI in your Java project:

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For non-Maven projects:

Download the latest release of the library here: Apache POI – Download Release Artifacts Extract the zip file and add the appropriate JAR files to your project’s classpath:- If you are reading and writing only Excel 2003 format, only the file poi-VERSION.jar is enough.- If you are reading and writing Excel 2007 format, you have to include the following files:

poi-ooxml-VERSION.jar poi-ooxml-schemas-VERSION.jar xmlbeans-VERSION.jar

For Maven projects: Add the following dependency to your project’s pom.xml file:

For Excel 2003 format only: org.apache.poi poi VERSION For Excel 2007 format: org.apache.poi poi-ooxml VERSION The latest stable version of Apache POI is 3.11 (at the time of writing this tutorial).

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What is poi in Excel?

1. Getting Apache POI library – Apache POI is the pure Java API for reading and writing Excel files in both formats XLS (Excel 2003 and earlier) and XLSX (Excel 2007 and later). To use Apache POI in your Java project:

For non-Maven projects:

Download the latest release of the library here: Apache POI – Download Release Artifacts Extract the zip file and add the appropriate JAR files to your project’s classpath:- If you are reading and writing only Excel 2003 format, only the file poi-VERSION.jar is enough.- If you are reading and writing Excel 2007 format, you have to include the following files:

poi-ooxml-VERSION.jar poi-ooxml-schemas-VERSION.jar xmlbeans-VERSION.jar

For Maven projects: Add the following dependency to your project’s pom.xml file:

For Excel 2003 format only: org.apache.poi poi VERSION For Excel 2007 format: org.apache.poi poi-ooxml VERSION The latest stable version of Apache POI is 3.11 (at the time of writing this tutorial).

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How to read an Excel file in Apache POI?

Apache POI – Read an excel file 1 Create workbook instance from excel sheet 2 Get to the desired sheet 3 Increment row number 4 iterate over all cells in a row 5 repeat step 3 and 4 until all data is read
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Is it possible to generate Excel files using Java Spring Boot?

Writing a unit test for our code – All good programmers test their code. I know, it’s hard, but our Excel Sheet is no exception. And that’s no simple matter. If you have already read the excellent book from Kent Beck called Extreme Programming, you’ll know exactly what I mean.

  1. This is the most common way of doing it and our common base for a test case: @RunWith ( SpringRunner,
  2. Class ) @SpringBootTest @WebAppConfiguration public class ExcelTest } We are configuring JUnit to run specifically with Spring.
  3. Also, we are asking Spring to start a web application context in the background.

However, we also get hold of our context and initialize something called the MockMvc. It basically creates a mock web environment. @Autowired private WebApplicationContext wac ; private MockMvc mockMvc ; @Before public void setUpAbstractDbTest () It’s kind of a routine.

It makes Spring inject our test case with a web application context. Then, in the @Before method, which runs before all test methods, we can initialize the MockMvc with the context created by Spring. Once done, we are ready to implement our test method and send requests to the MockMVC framework. We start by sending a web request to our mock web application.

MvcResult mvcResult = this, mockMvc, perform ( MockMvcRequestBuilders, get ( “/my/excel” ) ), andDo ( ResultHandler, print ()), andExpect ( StatusResultMatcher, status (). isOk ()), andExpect ( RequestResultMatcher, request (). asyncStarted ()), andReturn (); The MockMvc class is built for testing.

  1. So it has additional methods to do basic checks on the result.
  2. As an example, we can print some parts of the result and check if the status is ok.
  3. Most importantly, if an asynchronous process has been started, which is the case when streaming like we do to output the Excel file.
  4. You probably already figured out that there is a problem.
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How do we compare excel sheets, when we “somehow” have to wait until we get the content? The code above does not have an actual result, it just starts the stream. To get hold of the actual content, we have to do something like this: MvcResult result = this,

MockMvc, perform ( RequestBuilder, asyncDispatch ( mvcResult )), andReturn (); byte workbookBytes = result, getResponse (). getContentAsByteArray (); In the code above we are actually waiting for the request to be processed and the result to be returned from server. Eventually, we can read the content, which is, first of all, an array of bytes.

sigh Of course it is! But now that we have that content, we can bring it back to excel and compare it. This is how it will look in code: Workbook actual = new XSSFWorkbook ( new ByteArrayInputStream ( workbookBytes )); String actualValue = actual, getSheetAt ( 0 ),
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