如何使用Apache POI解析保存在Excel文件中的树结构

Question

All,

Good Morning!

I have an excel file with data listed as the following, I'm trying to parse down using POI

A           
    B       
        C   
            D1
            D2
        F   
            G1
            G2
            G3
        M   
            S1
    R       
        T   
    U       
L           
    X       
        Y   
            Z

is it possible to generate an output like the following

A
A-->B
A-->B-->C
A-->B-->C-->D1
A-->B-->C-->D2
A-->B-->F
A-->B-->F-->G1
A-->B-->F-->G2
A-->B-->F-->G3
A-->B-->M
A-->B-->M-->S1
A-->R
A-->R-->T
A-->U
L
L-->X
L-->X-->Y
L-->X-->Y-->Z

I have been trying from quite some time but havent figured out the logic

Thanks

Answer 1

Solution in Java, using Apache POI:

import java.io.File;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ParseTreeDemo 
{
    private static final int NUM_COLUMNS = 4;

    public static void main(String[] args)
    {

        try
        {
            FileInputStream file = new FileInputStream(new File("Test.xlsx"));

            XSSFWorkbook workbook = new XSSFWorkbook(file);
            XSSFSheet sheet = workbook.getSheetAt(0);

            // Use a column marker to save the 'farthest' column so far
            int currColMarker = -1;
            List<String> list = new ArrayList<>();

            //Iterate through each rows one by one
            Iterator<Row> rowIterator = sheet.iterator();
            while (rowIterator.hasNext()) 
            {
                Row row = rowIterator.next();

                for(int currCol = 0; currCol < NUM_COLUMNS; currCol++)
                {
                    Cell cell = row.getCell(currCol);
                    if(cell == null)
                        continue;

                    if(cell.getCellType() == Cell.CELL_TYPE_STRING) {

                        if(currCol > currColMarker) {

                            // A farther column, simply append and
                            // update column marker
                            currColMarker = currCol;

                            list.add(cell.getStringCellValue());
                        }
                        else if (currCol == currColMarker) {

                            // At same level as column marker
                            // Remove old value at same level, before appending
                            list.remove(list.size() - 1);
                            list.add(cell.getStringCellValue());
                        }
                        else {

                            // At a 'nearer' column, remove those values beyond
                            // this level before appending
                            currColMarker = currCol;

                            list = list.subList(0, currCol);
                            list.add(cell.getStringCellValue());
                        }
                    }
                }

                // For displaying the current contents
                StringBuilder sb = new StringBuilder();
                for(String s : list) {
                    if(sb.length() != 0) {
                        sb.append("-->");
                    }
                    sb.append(s);
                }
                System.out.println(sb.toString());

            }
            file.close();
        } 
        catch (Exception e) 
        {
            e.printStackTrace();
        }
    }
}

Output:

A
A-->B
A-->B-->C
A-->B-->C-->D1
A-->B-->C-->D2
A-->B-->F
A-->B-->F-->G1
A-->B-->F-->G2
A-->B-->F-->G3
A-->B-->M
A-->B-->M-->S1
A-->R
A-->R-->T
A-->U
L
L-->X
L-->X-->Y
L-->X-->Y-->Z

The idea:

• Use a 'column marker' to keep track of the active column
• If the new value is at a column, with a larger column value, append
• If it has the same column value, remove the last value, and append
• If it has a smaller column value, remove all current values beyond the new column value, before appending

Note: Test.xlsx contains the values as stated in the question.

Answer 2

If the listed data is in a variable called data , the following will work in Tcl:

proc merge {a b} {
    set res {}
    foreach ac [split $a {}] bc [split $b {}] {
        if {![string is space $ac] && [string is space -strict $bc]} {
            append res $ac
        } else {
            append res $bc
        }
    }
    set res
}

set current {}
foreach line [split [string trim $data] \n] {
    set current [merge $current [string trimright $line]]
    puts [join $current -->]
}

I originally went with a pseudo-stack approach, but it seemed simpler to "merge" each new line with the accumulated line ( current ) such that non-blank text in the new line would overwrite text in the accumulated line, and that the accumulated line would be truncated if the new line was shorter (after trimming off trailing whitespace from it).

Once I had the merged line, I could take advantage of the fact that (most) strings in Tcl are also lists, and print it as a string formed by joining the words using "-->" tokens.

Documentation: append , foreach , if , proc , puts , set , split , string