Interpret the "JXL" framework technical principle in the Java class library
JXL is a Java class library for operating the MicroSoft Excel file. It provides a set of APIs to read, write and modify Excel files.In this article, we will explore the technical principles of the JXL framework and provide some Java code examples to help readers better understand.
The principle of JXL is mainly based on the data structure and format of the Microsoft Excel file.Excel file is composed of multiple worksheets, and each worksheet consists of multiple rows and colums.JXL transformed them into the Java object model by analyzing the binary data of the Excel file to operate these worksheets, rows and columns.
The following is a sample code fragment that demonstrates how to use JXL to read the data in the Excel file:
import jxl.*;
public class ExcelReader {
public static void main(String[] args) {
try {
Workbook workbook = Workbook.getWorkbook(new File("input.xls"));
Sheet sheet = workbook.getsheet (0); // Get the first worksheet
int numRows = sheet.getRows();
int numCols = sheet.getColumns();
for (int i = 0; i < numRows; i++) {
for (int j = 0; j < numCols; j++) {
Cell cell = sheet.getCell(j, i);
System.out.print(cell.getContents() + "\t");
}
System.out.println();
}
workbook.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above code, we use the Workbook and Sheet objects to obtain the data of the worksheet from the Excel file.By calling the Getrows () and GetColumns () methods of Sheet objects, we can obtain the number of rows and columns in the worksheet.Then, the nested cycle traverses each cell (cell) and uses the getcell () method to obtain the specified cell.Finally, the contents of the cell by calling the getContents () method of getcell () to get the content of the cell and print it to the console.
In addition to reading Excel files, JXL also provides some APIs to create, write and modify Excel files.The following is a sample code fragment that demonstrates how to use JXL to create a new Excel file and write data to it:
import jxl.*;
import jxl.write.*;
public class ExcelWriter {
public static void main(String[] args) {
try {
WritableWorkbook workbook = Workbook.createWorkbook(new File("output.xls"));
WritableSheet Sheet = Workbook.createSheet ("Sheet1", 0); // Create a worksheet called "Sheet1"
Label label = new Label(0, 0, "Hello");
sheet.addCell(label);
Number number = new Number(1, 0, 123.45);
sheet.addCell(number);
workbook.write();
workbook.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above code, we use WritableWorkbook and WritableSheet objects to create a new Excel file and worksheet.By creating Label objects and Number objects, we can write text and numbers to the specified location of the worksheet.Finally, by calling the WRITE () method of the WritableWorkbook object, it is saved to the file and closes Workbook through the Close () method.
Summary: The technical principles of the JXL framework are based on the binary data of the Excel file, and converted it into the Java object model to achieve the reading, writing and modification of the Excel file.With JXL, we can easily operate the Excel file to achieve the functions of various data processing and report generation.It is hoped that the Java code example provided in this article can help readers better understand the principles and usage of the JXL framework.
