Turn your JAVA Beans into a POI Excel Spreadsheet (@author Jeff Byrd)

Bean2Excel.java

/**
 * Source: Turn your JAVA Beans into a POI Excel Spreadsheet http://www.dominotricks.com/?p=115
 * 
 * @author Jeff Byrd
 * 
 */
public class Bean2Excel {
  private HSSFWorkbook workbook;

  private HSSFFont boldFont;

  private HSSFDataFormat format;

  public static void main(String[] args) {

    // Used to create the hire dates
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy, MM, dd");

    try {
      // Create the report object
      Bean2Excel oReport = new Bean2Excel();

      // Create a list of employee data
      List<Employee> employees = new ArrayList<Employee>();
      employees.add(new Employee(100, "Abe Adams", sdf.parse("2009, 12, 1"), 10000.00));
      employees.add(new Employee(101, "Betty Barnes", sdf.parse("2010, 11, 1"), 11000.00));
      employees.add(new Employee(102, "Caleb Crown", sdf.parse("2011, 10, 1"), 12000.00));
      employees.add(new Employee(103, "Dirk Daniels", sdf.parse("2012, 09, 1"), 13000.00));

      // Create an array of report column objects
      ReportColumn[] reportColumns = new ReportColumn[] { new ReportColumn("id", "Id", FormatType.INTEGER),
          new ReportColumn("name", "Last Name", FormatType.TEXT),
          new ReportColumn("hireDate", "Hire Date", FormatType.DATE),
          new ReportColumn("salary", "Salary", FormatType.MONEY) };

      // Create a worksheet with our employee data and report columns
      oReport.addSheet(employees, reportColumns, "sheet1");

      // Set the Hire Date Column text to Bold and background to Green
      reportColumns[2].setColor(HSSFColor.GREEN.index);

      // Add a 2nd sheet with the same data.
      oReport.addSheet(employees, reportColumns, "sheet2");

      // Create an output stream to write the report to.
      OutputStream output = new FileOutputStream("c:\\temp\\report1.xls");

      // Write the report to the output stream
      oReport.write(output);

      // Finally, save the report
      output.close();

    } catch (ParseException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (FileNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }

  public Bean2Excel() {
    workbook = new HSSFWorkbook();
    boldFont = workbook.createFont();
    boldFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
    format = workbook.createDataFormat();
  }

  public void addSheet(List<?> data, ReportColumn[] columns, String sheetName) {

    HSSFSheet sheet = workbook.createSheet(sheetName);
    int numCols = columns.length;
    int currentRow = 0;
    HSSFRow row;

    try {

      // Create the report header at row 0
      row = sheet.createRow(currentRow);
      // Loop over all the column beans and populate the report headers
      for (int i = 0; i < numCols; i++) {
        // Get the header text from the bean and write it to the cell
        writeCell(row, i, columns[i].getHeader(), FormatType.TEXT, null, this.boldFont);
      }

      currentRow++; // increment the spreadsheet row before we step into
      // the data

      // Write report rows
      for (int i = 0; i < data.size(); i++) {
        // create a row in the spreadsheet
        row = sheet.createRow(currentRow++);
        // get the bean for the current row
        Object bean = data.get(i);
        // For each column object, create a column on the current row
        for (int y = 0; y < numCols; y++) {
          Object value = PropertyUtils.getProperty(bean, columns[y].getMethod());
          writeCell(row, y, value, columns[y].getType(), columns[y].getColor(), columns[y].getFont());
        }
      }

      // Autosize columns
      for (int i = 0; i < numCols; i++) {
        sheet.autoSizeColumn((short) i);
      }

    } catch (Exception e) {
      System.err.println("Caught Generate Error exception: " + e.getMessage());
    }

  }

  public HSSFFont boldFont() {
    return boldFont;
  }

  public void write(OutputStream outputStream) throws Exception {
    workbook.write(outputStream);
  }

  private void writeCell(HSSFRow row, int col, Object value, FormatType formatType, Short bgColor, HSSFFont font)
      throws Exception {

    HSSFCell cell = HSSFCellUtil.createCell(row, col, null);

    if (value == null) {
      return;
    }

    if (font != null) {
      HSSFCellStyle style = workbook.createCellStyle();
      style.setFont(font);
      cell.setCellStyle(style);
    }

    switch (formatType) {
    case TEXT:
      cell.setCellValue(value.toString());
      break;
    case INTEGER:
      cell.setCellValue(((Number) value).intValue());
      HSSFCellUtil.setCellStyleProperty(cell, workbook, CellUtil.DATA_FORMAT,
          HSSFDataFormat.getBuiltinFormat(("#,##0")));
      break;
    case FLOAT:
      cell.setCellValue(((Number) value).doubleValue());
      HSSFCellUtil.setCellStyleProperty(cell, workbook, CellUtil.DATA_FORMAT,
          HSSFDataFormat.getBuiltinFormat(("#,##0.00")));
      break;
    case DATE:
      cell.setCellValue((Date) value);
      HSSFCellUtil.setCellStyleProperty(cell, workbook, CellUtil.DATA_FORMAT,
          HSSFDataFormat.getBuiltinFormat(("m/d/yy")));
      break;
    case DATE_TIME:
      cell.setCellValue((Date) value);
      HSSFCellUtil.setCellStyleProperty(cell, workbook, CellUtil.DATA_FORMAT,
          HSSFDataFormat.getBuiltinFormat(("m/d/yy h:mm"))); // TODO: seconds (not easy)
      break;
    case MONEY:
      cell.setCellValue(((Number) value).intValue());
      HSSFCellUtil.setCellStyleProperty(cell, workbook, CellUtil.DATA_FORMAT, format.getFormat("$#,##0.00;$#,##0.00"));
      break;
    case PERCENTAGE:
      cell.setCellValue(((Number) value).doubleValue());
      HSSFCellUtil.setCellStyleProperty(cell, workbook, CellUtil.DATA_FORMAT, HSSFDataFormat.getBuiltinFormat("0.00%"));
    }

    if (bgColor != null) {
      HSSFCellUtil.setCellStyleProperty(cell, workbook, CellUtil.FILL_FOREGROUND_COLOR, bgColor);
      HSSFCellUtil.setCellStyleProperty(cell, workbook, CellUtil.FILL_PATTERN, HSSFCellStyle.SOLID_FOREGROUND);
    }

  }

  public enum FormatType {
    TEXT,
    INTEGER,
    FLOAT,
    DATE,
    DATE_TIME,
    MONEY,
    PERCENTAGE
  }
}

Employee.java

/**
 * Source: Turn your JAVA Beans into a POI Excel Spreadsheet http://www.dominotricks.com/?p=115
 * 
 * @author Jeff Byrd
 * 
 */
public class Employee {
  private String m_name;

  private Integer m_id;

  private Date m_hireDate;

  private Double m_salary;

  public Employee() {
  }

  public Employee(Integer id, String name, Date hiredate, Double salary) {
    this.m_id = id;
    this.m_name = name;
    this.m_hireDate = hiredate;
    this.m_salary = salary;
  }

  public String getName() {
    return m_name;
  }

  public void setName(String name) {
    this.m_name = name;
  }

  public Integer getId() {
    return m_id;
  }

  public void setId(Integer id) {
    this.m_id = id;
  }

  public Date getHireDate() {
    return m_hireDate;
  }

  public void setHireDate(Date hireDate) {
    this.m_hireDate = hireDate;
  }

  public Double getSalary() {
    return m_salary;
  }

  public void setSalary(Double salary) {
    this.m_salary = salary;
  }
}

ReportColumn.java

/**
 * Source: Turn your JAVA Beans into a POI Excel Spreadsheet http://www.dominotricks.com/?p=115
 * 
 * @author Jeff Byrd
 * 
 */
public class ReportColumn {
  private String m_method;

  private String m_header;

  private FormatType m_type;

  private HSSFFont m_font;

  private Short m_color;

  public ReportColumn(String method, String header, FormatType type, HSSFFont font, Short color) {
    this.m_method = method;
    this.m_header = header;
    this.m_type = type;
    this.m_font = font;
    this.m_color = color;
  }

  public ReportColumn(String method, String header, FormatType type, HSSFFont font) {
    this(method, header, type, font, null);
  }

  public ReportColumn(String method, String header, FormatType type, Short color) {
    this(method, header, type, null, color);
  }

  public ReportColumn(String method, String header, FormatType type) {
    this(method, header, type, null, null);
  }

  public String getMethod() {
    return m_method;
  }

  public void setMethod(String method) {
    this.m_method = method;
  }

  public String getHeader() {
    return m_header;
  }

  public void setHeader(String header) {
    this.m_header = header;
  }

  public FormatType getType() {
    return m_type;
  }

  public void setType(FormatType type) {
    this.m_type = type;
  }

  public HSSFFont getFont() {
    return m_font;
  }

  public void setFont(HSSFFont m_font) {
    this.m_font = m_font;
  }

  public Short getColor() {
    return m_color;
  }

  public void setColor(Short m_color) {
    this.m_color = m_color;
  }
}