The Builder Mode in the Apache POI Framework: WorkbookBuilder
Apache POI is an open source framework for reading and writing Microsoft Office format files. It includes a series of APIs that can be used to create, read, and modify files such as Excel, Word, and PowerPoint.
In Apache POI, WorkbookBuilder is an implementation of the builder pattern used to create Workbook objects. The Workbook object represents an Excel file and has multiple implementations in POI, such as HSSFWorkbook for manipulating files in. xls format and XSSFWorkbook for manipulating files in. xlsx format.
WorkbookBuilder uses a smooth interface, providing a highly readable, easy-to-use, and flexible way to create Workbook objects. It builds the attributes and contents of the Workbook object step by step through a series of Method chaining. The following is the complete source code of WorkbookBuilder:
public class WorkbookBuilder {
private Workbook workbook;
public WorkbookBuilder() {
this.workbook = new XSSFWorkbook();
}
public WorkbookBuilder createSheet(String sheetName) {
workbook.createSheet(sheetName);
return this;
}
public WorkbookBuilder createRow(int sheetIndex, int rowIndex) {
workbook.getSheetAt(sheetIndex).createRow(rowIndex);
return this;
}
public WorkbookBuilder createCell(int sheetIndex, int rowIndex, int columnIndex, String value) {
Cell cell = workbook.getSheetAt(sheetIndex).getRow(rowIndex).createCell(columnIndex);
cell.setCellValue(value);
return this;
}
public Workbook build() {
return workbook;
}
}
The example code for creating a Workbook object using WorkbookBuilder is as follows:
Workbook workbook = new WorkbookBuilder()
.createSheet("Sheet1")
.createRow(0, 0)
.createCell(0, 0, 0, "Hello World!")
.build();
The above code first creates a WorkbookBuilder object, and then continuously calls the createSheet, createRow, and createCell methods through chain calls to create an Excel file containing one cell. Finally, the created Workbook object is obtained through the build method.
Summary:
The WorkbookBuilder in the Apache POI framework is an implementation of the builder pattern that provides a smooth interface for building Workbook objects. Using WorkbookBuilder can effectively reduce the complexity of code, improve its readability and maintainability. The builder pattern can help developers gradually build complex objects without the need to specify all parameters at once. This makes the construction process more flexible and makes the code easy to extend and modify.
