Poiji

Poiji is a tiny thread-safe 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.

Table of Contents

• Getting Started
• Usage
• Documentation
  • Annotations
  • Prefer Default Value
  • Sheet Name Option
  • Protected Excels
  • Annotation ExcelCellName
  • Super Class Inheritance
  • Annotation ExcelCellsJoinedByName
  • ExcelCellRange Annotation
  • Support Consumer Interface
  • Custom Casting Implementation
  • Parse UnknownCells
  • Optional Mandatory Headers and Cells
  • Debug Cells Formats
  • Modify Cells Formats
  • Read Excel Properties
  • Disable Cells Formats
  • Create Custom Formatting
  • Poi Sheet Support
  • Update Default Locale
• License

Getting Started

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

maven

<dependency>
  <groupId>com.github.ozlerhakan</groupId>
  <artifactId>poiji</artifactId>
  <version>4.6.0</version>
</dependency>

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

Usage

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>)
com.poiji.bind.Poiji#fromExcel(org.apache.poi.ss.usermodel.Sheet, java.lang.Class<T>)
com.poiji.bind.Poiji#fromExcel(org.apache.poi.ss.usermodel.Sheet, java.lang.Class<T>, com.poiji.option.PoijiOptions)
com.poiji.bind.Poiji#fromExcel(org.apache.poi.ss.usermodel.Sheet, java.lang.Class<T>, com.poiji.option.PoijiOptions, java.util.function.Consumer<? super T>)

com.poiji.bind.Poiji#fromExcelProperties(java.io.File, java.lang.Class<T>)
com.poiji.bind.Poiji#fromExcelProperties(java.io.File, java.lang.Class<T>, com.poiji.option.PoijiOptions)
com.poiji.bind.Poiji#fromExcelProperties(java.io.InputStream, com.poiji.exception.PoijiExcelType, java.lang.Class<T>)
com.poiji.bind.Poiji#fromExcelProperties(java.io.InputStream, com.poiji.exception.PoijiExcelType, java.lang.Class<T>, com.poiji.option.PoijiOptions)

PoijiOptions.PoijiOptionsBuilder Structure

com.poiji.option.PoijiOptions.PoijiOptionsBuilder
    #settings()
    #build()
    #dateLenient(boolean)
    #dateRegex(String)
    #datePattern(String)
    #dateTimeFormatter(java.time.format.DateTimeFormatter)
    #ignoreHiddenSheets(boolean)
    #password(String)
    #preferNullOverDefault(boolean)
    #settings(int)
    #sheetIndex(int)
    #skip(int)
    #limit(int)
    #trimCellValue(boolean)
    #headerStart(int)
    #withCasting(Casting)
    #withFormatting(Formatting)
    #caseInsensitive(boolean)
    #ignoreWhitespaces(boolean)
    #poijiNumberFormat(PoijiNumberFormat)
    #poijiLogCellFormat(PoijiLogCellFormat)
    #disableXLSXNumberCellFormat()
    #addListDelimiter(String)
    #setLocale(java.util.Locale)
    #rawData(boolean)

Documentation

Here are the list of features with examples that the latest version of Poiji supports.

Annotations

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;

    @ExcelCellName("emails")     (4)
    List<String> emails;

    @ExcelCell(5)
    List<BigDecimal> bills;

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

1. 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.LocalDate, java.time.LocalDateTime and String as well.

4. If one column contains multiple value, you can get them using a List field. A List field can store items which is of type BigDecimal, Long, Double, Float, Integer, Boolean and String.

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

ID	NAME	SURNAME	AGE	SINGLE	BILLS	EMAILS
123923	Joe	Doe	30	TRUE	123,10;99.99	[email protected];[email protected]
123123	Sophie	Derue	20	TRUE	1022	[email protected];[email protected]
135923	Paul	Raul	31	FALSE	73,25;70	[email protected];[email protected]

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

PoijiOptions options = PoijiOptions.PoijiOptionsBuilder.settings()
        .addListDelimiter(";") (1)
        .build();
List<Employee> employees = Poiji.fromExcel(new File("employees.xls"), Employee.class, options);
// 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, emails=[[email protected], [email protected]], biils=[123,10, 99.99]}

1. By default the delimiter/separator is , to split items in a cell. There is an option to change this behavior. Since we use ; between items, we need to tell Poiji to use ; as a separator.

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, emails=[[email protected], [email protected]], biils=[1022]}

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. == Documentation

Prefer Default Value

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.

Sheet Name Option

Poiji allows specifying the sheet name using annotation

@ExcelSheet("Sheet2")  (1)
public class Student {

    @ExcelCell(0)
    private String name;

    @ExcelCell(1)
    private String id;

    @ExcelCell(2)
    private String phone;


    @Override
    public String toString() {
        return "Student {" +
                " name=" + name +
                ", id=" + id + "'" +
                ", phone='" + phone + "'" +
                '}';
    }
}

1. With the ExcelSheet annotation we are configuring the name of the sheet to read data from. The other sheets will be ignored.

Protected Excels

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);

Annotation ExcelCellName

Using ExcelCellName, 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;

    @ExcelCellName(value = "", expression = "Surname|Second name")  (2)
    private String surname;

}

1. We need to specify the name of the column for which the corresponding value is looked. By default, @ExcelCellName is case-sensitive and the excel file should’t contain duplicated column names. However, you can manipulate this feature using PoijiOptionsBuilder#caseInsensitive(boolean) and you can ignore white spaces using PoijiOptionsBuilder#ignoreWhitespaces(boolean).

2. In rare situations a column can have synonyms, especially when the column was renamed and backward compatibility is needed. Here we specify the expression leaving the column name empty.

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

Name	Address	Age	Email	Surname
Joe	San Francisco, CA	30	[email protected]	Doe
Sophie	Costa Mesa, CA	20	[email protected]	Doe

List<Person> people = Poiji.fromExcel(new File("person.xls"), Person.class);
people.size();
// 2
Person person = people.get(0);
// Joe
// San Francisco, CA
// 30
// [email protected]
// Doe

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;

}

Super Class Inheritance

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

Annotation ExcelCellsJoinedByName

Using ExcelCellsJoinedByName we can read columns which name meets same regular expression. Values will be combined as a multi valued map.

Please pay attention the variable must be initialized explicitly.

public class Album {

    @ExcelCellsJoinedByName(expression = "Artist")  (1)
    private MultiValuedMap<String, String> artists = new ArrayListValuedHashMap<>();

    @ExcelCellsJoinedByName(expression = "Track[0-9]+")  (2)
    private MultiValuedMap<String, String> tracks = new ArrayListValuedHashMap<>();

}

1. Here we map multiple columns with name Artist.

2. Here we map multiple columns with name Track1, Track2, Track3, etc.

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

Artist	Artist	Artist	Track1	Track2
Michael Jackson	Lionel Richie	Stevie Wonder	We are the World	We are the World (instrumental)
artist 1	artist 1	artist 1	track 1	track 1

List<Album> albums = Poiji.fromExcel(new File("album.xls"), Album.class);
albums.size();
// 2
Album album1 = albums.get(0);
// artists = { Artist = [Michael Jackson, Lionel Richie, Stevie Wonder] }
// tracks = { Track1 = [We are the World], Track2 = [We are the World (instrumental)] }
Album album2 = albums.get(1);
// artists = {Artist = [artist 1, artist 1, artist 1] }
// tracks = {Track2 = [track 1], Track1=[track 1] }

Json presentation for album1 will be as follows

{
  "artists": {
    "Artist": [
      "Michael Jackson",
      "Lionel Richie",
      "Stevie Wonder"
    ]
  },
  "tracks": {
    "Track1": [
      "We are the World"
    ],
    "Track2": [
      "We are the World (instrumental)"
    ]
  }
}

ExcelCellRange Annotation

Consider you have a table like below:

No.	Personal Information					Credit Card Information
	Name	Age	City	State	Zip Code	Card Type	Last 4 Digits	Expiration Date
1	John Doe	21	Vienna	Virginia	22349	VISA	1234	Jan-21
2	Jane Doe	28	Greenbelt	Maryland	20993	MasterCard	2345	Jun-22
3	Paul Ryan	19	Alexandria	Virginia	22312	JCB	4567	Oct-24

The ExcelCellRange annotation lets us aggregate a range of information in one object model. In this case, we collect the data in PersonCreditInfo plus details of the person in PersonInfo and for the credit card in CardInfo:

public class PersonCreditInfo {

    @ExcelCellName("No.")
    private Integer no;

    @ExcelCellRange
    private PersonInfo personInfo;

    @ExcelCellRange
    private CardInfo cardInfo;

    public static class PersonInfo {
        @ExcelCellName("Name")
        private String name;
        @ExcelCellName("Age")
        private Integer age;
        @ExcelCellName("City")
        private String city;
        @ExcelCellName("State")
        private String state;
        @ExcelCellName("Zip Code")
        private String zipCode;
    }

    public static class CardInfo {
        @ExcelCellName("Card Type")
        private String type;
        @ExcelCellName("Last 4 Digits")
        private String last4Digits;
        @ExcelCellName("Expiration Date")
        private String expirationDate;
    }
}

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

PoijiOptions options = PoijiOptions.PoijiOptionsBuilder.settings().headerCount(2).build();
List<PersonCreditInfo> actualPersonalCredits = Poiji.fromExcel(new File(path), PersonCreditInfo.class, options);

PersonCreditInfo personCreditInfo1 = actualPersonalCredits.get(0);
PersonCreditInfo.PersonInfo expectedPerson1 = personCreditInfo1.getPersonInfo();
PersonCreditInfo.CardInfo expectedCard1 = personCreditInfo1.getCardInfo();

Support Consumer Interface

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);
}

Custom Casting Implementation

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);

Parse UnknownCells

You can annotate a Map<String, String> with @ExcelUnknownCells to parse all entries, which are not mapped in any other way (for example by index or by name).

This is our object model:

public class MusicTrack {

    @ExcelCellName("ID")
    private String employeeId;

    @ExcelCellName("AUTHOR")
    private String author;

    @ExcelCellName("NAME")
    private String name;

    @ExcelUnknownCells
    private Map<String, String> unknownCells;

}

This is the excel file we want to parse:

ID	AUTHOR	NAME	ENCODING	BITRATE
123923	Joe Doe	The example song	mp3	256
56437	Jane Doe	The random song	flac	1500

The object corresponding to the first row of the excel sheet then has a map with {ENCODING=mp3, BITRATE=256} and the one for the second row has {ENCODING=flac, BITRATE=1500}.

Note that If you use the PoijiOptionsBuilder#caseInsensitive(true) option, the ExcelUnknownCells map will be parsed with lowercase.

Optional Mandatory Headers and Cells

As of 4.0.0, @ExcelCellName and @ExcelCell are given to provide mandatoryHeader and mandatoryCell fields, meaning we can be more specific by declaring rules in headers or cells or both in excel files. mandatoryHeader expects the labeled excel column exists in a given excel file, while mandatoryCell looks into the values of the mentioned header/column. If any of the options is active and your excel breaks the rule, either a HeaderMissingException or PoijiMultiRowException will be thrown accordingly.

// default behavior
@ExcelCellName(value = "COLUMN_NAME", mandatoryHeader = false, mandatoryCell = false)
String fieldName;

// default behavior
@ExcelCell(value = COLUMN_INDEX, mandatoryHeader = false, mandatoryCell = false)
String fieldName;

Note	The mandatoryHeader field is compatible with XLS and XLSX files.

Note	The mandatoryCell field works only with XLS files and Sheet instances. XLS workbooks are opened with RETURN_BLANK_AS_NULL missing cell policy. If passing a Sheet instance it is up for the caller to make sure the missing cell policy of the parent workbook is set accordingly.

Debug Cells Formats

We can observe each cell format of a given excel file. Assume that we have an excel file like below:

Date

12/31/2020 12.00 AM

We can get all the list of cell formats using PoijiLogCellFormat with PoijiOptions:

PoijiLogCellFormat log = new PoijiLogCellFormat();
PoijiOptions options = PoijiOptions.PoijiOptionsBuilder.settings()
        .poijiCellFormat(log)
        .build();
List<Model> dates = Poiji.fromExcel(stream, poijiExcelType, Model.class, options);

Model model = rows.get(0)
model.getDate();
// 12.00

Hmm, It looks like we did not achieve the correct date format since we get the date value as (12.00). Let’s see how internally the excel file is being parsed via PoijiLogCellFormat:

List<InternalCellFormat> formats = log.formats();
InternalCellFormat cell10 = formats.get(1);

cell10.getFormatString()
// mm:ss.0
cell10.getFormatIndex()
// 47

Now that we know the reason of why we don’t see the expected date value, it’s because the default format of the date cell is the mm:ss.0 format with a given index 47, we need to change the default format of index (i.e. 47). This format was automatically assigned to the cell having a number, but almost certainly with a special style or format. Note that this option should be used for debugging purpose only.

Modify Cells Formats

We can change the default format of a cell using PoijiNumberFormat. Recall Debug Cells Formats, we are unable to see the correct cell format, what’s more the excel file uses another format which we do not want to.

Date

12/31/2020 12.00 AM

Using PoijiNumberFormat option, we are able to change the behavior of the format of a specific index:

PoijiNumberFormat numberFormat = new PoijiNumberFormat();
numberFormat.putNumberFormat((short) 47, "mm/dd/yyyy hh.mm aa");

PoijiOptions options = PoijiOptions.PoijiOptionsBuilder.settings()
        .poijiNumberFormat(numberFormat)
        .build();

List<Model> rows = Poiji.fromExcel(stream, poijiExcelType, Model.class, options);

Model model = rows.get(0)
model.getDate();
// 12/31/2020 12.00 AM  (1)

1. Voila!

We know that the index 47 uses the format mm:ss.0 by default in the given excel file, thus we’re able to override its format with mm/dd/yyyy hh.mm aa using the putNumberFormat method.

Read Excel Properties

It is possible to read excel properties from xlsx files. To achieve that, create a class with fields annotated with @ExcelProperty.

Example:

public class ExcelProperties {
    @ExcelProperty
    private String title;

    @ExcelProperty
    private String customProperty;
}

The field name corresponds to the name of the property inside the Excel file. To use a different one than the field name, you can specify a propertyName (e.g. @ExcelProperty(propertyName = "customPropertyName"))

The list of built-in (e.g. non-custom) properties in an Excel file, which can be read by Poiji can be found in the class DefaultExcelProperties.

Poiji can only read Text properties from an Excel file, so you have to use a String to read them. This does not apply to "modified", "lastPrinted" and "created", which are deserialized into a Date.

Disable Cells Formats

Consider we have a xls or xlsx excel file like below:

Amount

25,00

(50,00)

(65,00)

Since we use a cell format on line 4 and 5 (i.e. (50,00) and (65,00)), we don’t want to see the formatted value of each cell after processing. In order to do that, we can use @DisableCellFormatXLS on a field if the file ends with xls or disableXLSXNumberCellFormat() for xlsx files using PoijiOptions.

xls files

public class TestInfo {
    @ExcelCell(0)
    @DisableCellFormatXLS (1)
    public BigDecimal amount;
}

1. we only disable cell formats on the specified column.

xlsx files

public class TestInfo {
    @ExcelCell(0)
    private BigDecimal amount;
}

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

1. when disabling number cell format, we disable it in the entire cells for xlsx files.

and let Poiji ignores the cell formats:

List<TestInfo> result = Poiji.fromExcel(new File(path), TestInfo.class, options); (1)

result.get(1).amount
// -50

1. Add options, if your excel is xlsx file.

Create Custom Formatting

You can create your own formatting implementation without relying on the default Poiji formatting configuration using the Formatting interface.

public class MyFormatting implements Formatting {
    @Override
    public String transform(PoijiOptions options, String value) {
        return value.toUpperCase().trim(); (1)
    }
}

public class Person {

    @ExcelCellName("ID")
    protected String employeeId;

    @ExcelCellName("NAME")
    protected String name;

    @ExcelCellName("SURNAME")
    protected String surname;

}

1. Suppose that all the header names of an excel file have different formatting. Using custom formatting, we are able to look at headers with a custom format. All the headers will be uppercase and don’t have white spaces before and after.

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

PoijiOptions options = PoijiOptions.PoijiOptionsBuilder.settings()
                .withFormatting(new MyFormatting())
                .build();
List<Person> people = Poiji.fromExcel(excel, Person.class, options);

Poi Sheet Support

Poiji accepts excel records via Poi Sheet object as well:

File file = new File("/tmp/file.xlsx");
FileInputStream fileInputStream = new FileInputStream(file);
Workbook workbook = new XSSFWorkbook(fileInputStream);
Sheet sheet = workbook.getSheetAt(0);

List<Model> result = Poiji.fromExcel(sheet, Model.class);

Update Default Locale

For parsing numbers and dates java.lang.Locale is used. Also Apache Poi uses the Locale for parsing. As default, Poij uses Locale.US irrespective of Locale used on the running system. If you want to change that you can use a option to pass the Locale to be used like shown below.

In this example the Jvm default locale is used. Beware that if your code run’s on a other Jvm with another Locale set as default parsing could give different results. Better is to use a fixed locale. Also be aware of differences how Locales behave between Java 8 and 9+. For example AM/PM in Locale.GERMANY is displayed as AM/PM in Java 8 but Vorn./Nam. in Java 9 or higher. This is due to the changes in Java 9. See JEP-252 for more details.

PoijiOptions options = PoijiOptions.PoijiOptionsBuilder.settings()
                .setLocale(Locale.getDefault())
                .build();

License