rtslabs / poiji

:page_facing_up: A tiny framework converting excel data to Java objects based on Apache POI

Poiji

Poiji is a teeny Java framework that provides one way mapping from Excel sheets to Java classes. In a way it lets us convert each row of the specified excel data into Java objects. Poiji uses Apache Poi (the Java API for Microsoft Documents) under the hood to fulfill the mapping process.

How it works

In your Maven/Gradle project, first add the corresponding dependency:

maven

<dependency>
  <groupId>com.github.ozlerhakan</groupId>
  <artifactId>poiji</artifactId>
  <version>1.8</version>
</dependency>

gradle

dependencies {
    compile 'com.github.ozlerhakan:poiji:1.8'
}

You can find the latest and earlier development versions including javadoc and source files on Sonatypes OSS repository.

Example 1

Create your object model:

public class Employee {

    @ExcelCell(0)                (1)
    private long employeeId;     (2)

    @ExcelCell(1)
    private String name;

    @ExcelCell(2)
    private String surname;

    @ExcelCell(3)
    private int age;

    @ExcelCell(4)
    private boolean single;

    @ExcelCell(5)
    private String birthday;

    //no need getters/setters to map excel cells to fields

    @Override
    public String toString() {
        return "Employee{" +
                "employeeId=" + employeeId +
                ", name='" + name + '\'' +
                ", surname='" + surname + '\'' +
                ", age=" + age +
                ", single=" + single +
                ", birthday='" + birthday + '\'' +
                '}';
    }
}

1. a field must be annotated with @ExcelCell along with its property in order to get the value from the right coordinate in the target excel sheet.

2. an annotated field can be either protected, private or public modifier. The field may be either of boolean, int, long, float, double, java.util.Date or String.

This is the excel file (employees.xlsx) we want to map to a list of Employee instance:

ID	NAME	SURNAME	AGE	SINGLE	BIRTHDAY
123923	Joe	Doe	30	TRUE	4/9/1987
123123	Sophie	Derue	20	TRUE	5/3/1997
135923	Paul	Raul	31	FALSE	4/9/1986

The snippet below shows how to obtain the excel data using Poiji.

List<Employee> employees = Poiji.fromExcel(new File("employees.xls"), Employee.class);
employees.size();
// 3
Employee firstEmployee = employees.get(0);
// Employee{employeeId=123923, name='Joe', surname='Doe', age=30, single=true, birthday='4/9/1987'}

By default, Poiji ignores the first row of the excel data. You can override this behaviour by setting a PoijiOptions.

PoijiOptions options = PoijiOptionsBuilder.settings(2).build();
List<Employee> employees = Poiji.fromExcel(new File("employees.xls"), Employee.class, options);
Employee firstEmployee = employees.get(0);
// Employee{employeeId=123123, name='Sophie', surname='Derue', age=20, single=true, birthday='5/3/1997'}

By default, Poiji selects the first sheet of an excel file. You can override this behaviour like below:

PoijiOptions options = PoijiOptionsBuilder.settings()
                       .sheetIndex(1) (1)
                       .build();

1. Poiji should look at the second (zero-based index) sheet of your excel file.

If you want a date field to return null rather than a default date, use PoijiOptionsBuilder with the preferNullOverDefault method as follows:

PoijiOptions options = PoijiOptionsBuilder.settings()
                       .preferNullOverDefault(true) (1)
                       .build();

1. Annotated date fields will have a null value, if the specified date pattern cannot be parsed.

Example 2

Your object model may be derived from a super class:

public abstract class Vehicle {

    @ExcelCell(0)
    protected String name;

    @ExcelCell(1)
    protected int year;
}

public class Car extends Vehicle {

    @ExcelCell(2)
    private int nOfSeats;
}

and you want to map the table (car.xlsx) below to Car objects:

NAME	YEAR	SEATS
Honda Civic	2017	4
Chevrolet Corvette	2017	2

Using Poiji, you can map the annotated field(s) of super class(es) of the target class like so:

List<Car> cars = Poiji.fromExcel(new File("cars.xls"), Car.class);
cars.size();
// 2
Car car = cars.get(0);
// Honda Civic
// 2017
// 4

Try with JShell

Since we have a new pedagogic tool, Java 9 REPL, you can try Poiji in JShell. Clone the repo and follow the steps below. JShell should open up a new jshell session once loading the startup scripts and the specified jars that must be in the classpath. You must first import and create related packages and classes before using Poiji. We are able to use directly Poiji and Employee classes because they are already imported from jshell/snippets with try-with-jshell.sh.

$ cd poiji/

$ ./try-with-jshell.sh
|  Welcome to JShell -- Version 9
|  For an introduction type: /help intro

jshell> List<Employee> employees = Poiji.fromExcel(new File("src/test/resources/employees.xlsx"), Employee.class);

jshell> employees.forEach(System.out::println)
Employee{employeeId=123923, name='Joe', surname='Doe', age=30, single=true, birthday='4/9/1987'}
Employee{employeeId=123123, name='Sophie', surname='Derue', age=20, single=false, birthday='5/3/1997'}
Employee{employeeId=135923, name='Paul', surname='Raul', age=31, single=false, birthday='4/9/1986'}

License

MIT