Poiji

Poiji is a teeny Java library 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>1.22.0</version>
</dependency>

gradle

dependencies {
    compile 'com.github.ozlerhakan:poiji:1.22.0'
}

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

Poiji.fromExcel Structure

com.poiji.bind.Poiji#fromExcel(java.io.File, java.lang.Class<T>)
com.poiji.bind.Poiji#fromExcel(java.io.File, java.lang.Class<T>, java.util.function.Consumer<? super T>)
com.poiji.bind.Poiji#fromExcel(java.io.File, java.lang.Class<T>, com.poiji.option.PoijiOptions)
com.poiji.bind.Poiji#fromExcel(java.io.File, java.lang.Class<T>, com.poiji.option.PoijiOptions, java.util.function.Consumer<? super T>)
com.poiji.bind.Poiji#fromExcel(java.io.InputStream, com.poiji.exception.PoijiExcelType, java.lang.Class<T>)
com.poiji.bind.Poiji#fromExcel(java.io.InputStream, com.poiji.exception.PoijiExcelType, java.lang.Class<T>, java.util.function.Consumer<? super T>)
com.poiji.bind.Poiji#fromExcel(java.io.InputStream, com.poiji.exception.PoijiExcelType, java.lang.Class<T>, com.poiji.option.PoijiOptions)
com.poiji.bind.Poiji#fromExcel(java.io.InputStream, com.poiji.exception.PoijiExcelType, java.lang.Class<T>, com.poiji.option.PoijiOptions, java.util.function.Consumer<? super T>)

PoijiOptions.PoijiOptionsBuilder Structure

com.poiji.option.PoijiOptions.PoijiOptionsBuilder#settings()
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#build()
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#dateLenient(boolean)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#dateRegex(String)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#datePattern(String)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#dateTimeFormatter(java.time.format.DateTimeFormatter)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#ignoreHiddenSheets(boolean)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#password(String)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#preferNullOverDefault(boolean)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#settings(int)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#sheetIndex(int)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#skip(int)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#trimCellValue(boolean)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#headerStart(int)
com.poiji.option.PoijiOptions.PoijiOptionsBuilder#withCasting(Casting)

Example 1

Create your object model:

public class Employee {

    @ExcelRow                    (1)
    private int rowIndex;

    @ExcelCell(0)                (2)
    private long employeeId;     (3)

    @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{" +
                "rowIndex=" + rowIndex +
                ", employeeId=" + employeeId +
                ", name='" + name + '\'' +
                ", surname='" + surname + '\'' +
                ", age=" + age +
                ", single=" + single +
                ", birthday='" + birthday + '\'' +
                '}';
    }
}

1. As of 1.10, optionally we can access the index of each row item by using the ExcelRow annotation. Annotated variable should be of type int, double, float or long.

2. 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.

3. An annotated field can be either protected, private or public modifier. The field may be either of boolean, int, long, float, double, or their wrapper classes. You can add a field of java.util.Date, java.time.DateTime and String as well.

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);
// alternatively
InputStream stream = new FileInputStream(new File("employees.xls"))
List<Employee> employees = Poiji.fromExcel(stream, PoijiExcelType.XLS, Employee.class, options);

employees.size();
// 3
Employee firstEmployee = employees.get(0);
// Employee{rowIndex=1, employeeId=123923, name='Joe', surname='Doe', age=30, single=true, birthday='4/9/1987'}

By default, Poiji ignores the header row of the excel data. If you want to ignore the first row of data, you need to use PoijiOptions.

PoijiOptions options = PoijiOptionsBuilder.settings(1).build(); // we eliminate Joe Doe.
List<Employee> employees = Poiji.fromExcel(new File("employees.xls"), Employee.class, options);
Employee firstEmployee = employees.get(0);
// Employee{rowIndex=2, 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. a field that is of type either java.util.Date, Float, Double, Integer, Long or String will have a null value.

Encrypted Excel Files

Consider that your excel file is protected with a password, you can define the password via PoijiOptionsBuilder to read rows:

PoijiOptions options = PoijiOptionsBuilder.settings()
                    .password("1234")
                    .build();
List<Employee> employees = Poiji.fromExcel(new File("employees.xls"), Employee.class, options);

Example 2

The version 1.11 introduces a new annotation called ExcelCellName so that we can read the values by column names directly.

public class Person {

    @ExcelCellName("Name")  (1)
    protected String name;

    @ExcelCellName("Address")
    protected String address;

    @ExcelCellName("Age")
    protected int age;

    @ExcelCellName("Email")
    protected String email;

}

1. We need to specify the name of the column for which the corresponding value is looked. @ExcelCellName is case-sensitive and the excel file should’t contain duplicated column names.

For example, here is the excel (person.xls) file we want to use:

Name	Address	Age	Email
Joe	San Francisco, CA	30	joe@doe.com
Sophie	Costa Mesa, CA	20	sophie@doe.com

List<Person> people = Poiji.fromExcel(new File("person.xls"), Person.class);
people.size();
// 2
Person person = people.get(0);
// Joe
// San Francisco, CA
// 30
// joe@doe.com

Given that the first column always stands for the names of people, you’re able to combine the ExcelCell annotation with ExcelCellName in your object model:

public class Person {

    @ExcelCell(0)
    protected String name;

    @ExcelCellName("Address")
    protected String address;

    @ExcelCellName("Age")
    protected int age;

    @ExcelCellName("Email")
    protected String email;

}

Example 3

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

Example 4

Consider you have a table like below:

Group A			Group B
NameA	AgeA	CityA	NameB	AgeB	CityB
John Doe	21	Vienna	Smith Michael	32	McLean
Jane Doe	28	Greenbelt	Sean Paul	25	Los Angeles
Paul Ryan	19	Alexandria	John Peter	25	Vienna
Peter Pan	23	Alexandria	Arnold Regan	35	Seattle

The new ExcelCellRange annotation (as of 1.19) lets us aggregate a range of information in one object model. In this case, we collect the details of the first person in classA and for second person in classB:

public class Groups {

  @ExcelCellRange
  private GroupA groupA;

  @ExcelCellRange
  private GroupB groupB;

}

public class GroupA {

    @ExcelCellName("NameA")
    private String name;

    @ExcelCellName("AgeA")
    private Integer age;

    @ExcelCellName("CityA")
    private String city;

}

public class GroupB {

    @ExcelCellName("NameB")
    private String name;

    @ExcelCellName("AgeB")
    private Integer age;

    @ExcelCellName("CityB")
    private String city;
}

Using the conventional way, we can retrieve the data using Poiji.fromExcel:

PoijiOptions options = PoijiOptionsBuilder.settings().headerStart(1).build(); // header starts at 1 (zero-based).
List<Groups> groups = Poiji.fromExcel(new File(excel), Groups.class, options);

Groups firstRowGroups = actualGroups.get(0);

GroupA firstRowPerson1 = firstRowGroups.getGroupA();
GroupB secondRowPerson2 = firstRowGroups.getGroupB();

Example 5

As of 1.14, Poiji supports Consumer Interface. As @fmarazita explained the usage, there are several benefits of having a Consumer:

1. Huge excel file ( without you have all in memory)

2. Run time processing/filtering data

3. DB batch insertion

For example, we have a Calculation entity class and want to insert each row into a database while retrieving:

class Calculation {

  @ExcelCell(0)
  String name

  @ExcelCell(1)
  int a

  @ExcelCell(2)
  int b

  public int getA(){
    return a;
  }

  public int getB(){
    return b;
  }

  public int getName(){
    return name;
  }

}

File fileCalculation = new File(example.xlsx);

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

Poiji.fromExcel(fileCalculation, Calculation.class, options, this::dbInsertion);

private void dbInsertion(Calculation siCalculation) {
  int value= siCalculation.getA() + siCalculation.getB();
  String name = siCalculation.getName();
  insertDB(name , value);
}

Example 6

Since Poiji 1.19.1, you can create your own casting implementation without relying on the default Poiji casting configuration using the Casting interface.

public class MyCasting implements Casting {
    @Override
    public Object castValue(Class<?> fieldType, String value, PoijiOptions options) {
       return value.trim();
    }
}

public class Person {

    @ExcelCell(0)
    protected String employeeId;

    @ExcelCell(1)
    protected String name;

    @ExcelCell(2)
    protected String surname;

}

Then you can add your custom implementation with the withCasting method:

 PoijiOptions options = PoijiOptions.PoijiOptionsBuilder.settings()
                .withCasting(new MyCasting())
                .build();

List<Person> people = Poiji.fromExcel(excel, Person.class, options);

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'}

Stargazers over time

License

MIT