避免在抽象类的子类上重复代码

Question

I'm working on an old Struts application which has an abstract action to create Excel exports by filling Excel template files.

Each Excel export action extends this parent class and adds its own implementation for filling the Excel template and defines its own template and output filename.

public abstract class ExcelExportAction extends BaseAction {
    protected abstract String getInputFilename();
    protected abstract String getOutputFilename();
    protected abstract HSSFWorkbook modifyWorkbook(HSSFWorkbook workbook, HttpServletRequest request);

    @Override
    protected final ActionForward run(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
    throws Exception {

        Workbook workbook = new Workbook(getInputFilename());
        workbook = modifyWorkbook(workbook, request);
        addWorkBookToResponse(workbook, getOutputFilename());       

        return null;
    }
...
}

Implementations are looking like this and this is where the code duplication is "warned" by SonarQube:

public class BudgetReportExcelAction extends ExcelExportAction {
    private static final String INPUT_FILENAME = "Report-Budget-Template.xls";
    private static final String OUTPUT_FILENAME = "Report-Customerbudget.xls";

    @Override
    protected String getInputFilename() {
        return INPUT_FILENAME;
    }
    @Override
    protected String getOutputFilename() {
        return OUTPUT_FILENAME;
    }
    @Override
    protected HSSFWorkbook modifyWorkbook(HSSFWorkbook workbook, HttpServletRequest request) {
        /* modify the workbook */
        return workbook;
    }
}

Any ideas how to avoid the duplication?

Answer 1

我在这里看到的代码几乎没有任何代码重复，但是如果您真的想“从石头上榨水”，则可以向基类添加一个构造函数，该构造函数接受输入文件名和输出文件名，并且使每个派生类将其输入文件名和输出文件名传递给基类的构造函数。

Answer 2

A non-answer here: there is no "code duplication" in your examples.

The point is: your abstract class drives a certain "layout" for your child class; but that is the essence of using an abstract class.

In other words: nothing to worry about here.

You are following well known, "approved" patterns; for example by nicely using the @Override annotation in your child class.

All fine, have a nice day!