feature: 指定某一列，当相邻单元格内容一致时合并处理

fastexcel-core/src/main/java/cn/idev/excel/write/merge/DynamicMergeStrategy.java

@@ -0,0 +1,80 @@
+package cn.idev.excel.write.merge;
+
+import cn.idev.excel.write.handler.RowWriteHandler;
+import cn.idev.excel.write.handler.context.RowWriteHandlerContext;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.util.CellRangeAddress;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+
+/**
+ * @Description 指定列数据相同时进行单元格合并
+ * @Author Zhuojianlong
+ * @Date 2025/3/8
+ */
+public class DynamicMergeStrategy implements RowWriteHandler {
+    private final int columnIndex;
+    private final int columnExtend;
+    private final int dataSize;
+    private final Deque<MergeRow> rowStack = new ArrayDeque<>();
+
+    public DynamicMergeStrategy(int columnIndex,int dataSize) {
+        this(columnIndex,1,dataSize);
+    }
+    public DynamicMergeStrategy(int columnIndex, int columnExtend,int dataSize) {
+        if (columnExtend < 1) {
+            throw new IllegalArgumentException("ColumnExtend must be greater than 1");
+        }
+        if (columnIndex < 0) {
+            throw new IllegalArgumentException("ColumnIndex must be greater than 0");
+        }
+        this.columnIndex = columnIndex;
+        this.columnExtend = columnExtend;
+        this.dataSize = dataSize;
+
+    }
+    @Override
+    public void afterRowDispose(RowWriteHandlerContext context) {
+        if (context.getHead() || context.getRelativeRowIndex() == null) {
+            return;
+        }
+        Row row = context.getRow();
+        rowStack.push(new MergeRow(row, context.getRelativeRowIndex()));
+        if(context.getRelativeRowIndex()==(dataSize-1)){
+            while (!rowStack.isEmpty()){
+                MergeRow lastRow  = rowStack.pop();
+                while (!rowStack.isEmpty()){
+                    MergeRow prevRow = rowStack.pop();
+                    if(prevRow.getRelativeRowIndex().equals(0)){
+                        CellRangeAddress cellRangeAddress = new CellRangeAddress(prevRow.getRow().getRowNum(),
+                            lastRow.getRow().getRowNum(), columnIndex, columnIndex + columnExtend - 1);
+                        context.getWriteSheetHolder().getSheet().addMergedRegionUnsafe(cellRangeAddress);
+                    }else {
+                        if (!prevRow.getRow().getCell(columnIndex).getStringCellValue().equals(lastRow.getRow().getCell(columnIndex).getStringCellValue())) {
+                            if(lastRow.getRow().getRowNum()!=(prevRow.getRow().getRowNum()+1)){
+                                CellRangeAddress cellRangeAddress = new CellRangeAddress(prevRow.getRow().getRowNum()+1,
+                                    lastRow.getRow().getRowNum(), columnIndex, columnIndex + columnExtend - 1);
+                                context.getWriteSheetHolder().getSheet().addMergedRegionUnsafe(cellRangeAddress);
+                            }
+                            rowStack.push(prevRow);
+                            break;
+                        }
+                    }
+
+                }
+
+            }
+        }
+
+    }
+
+    @Data
+    @AllArgsConstructor
+    public static  class MergeRow{
+        private Row row;
+        private Integer relativeRowIndex;
+    }
+}

fastexcel-test/src/test/java/cn/idev/excel/test/demo/write/WriteTest.java

@@ -3,11 +3,7 @@
 import java.io.File;
 import java.io.InputStream;
 import java.net.URL;
-import java.util.ArrayList;
-import java.util.Date;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
 import cn.idev.excel.EasyExcel;
 import cn.idev.excel.ExcelWriter;
@@ -18,6 +14,7 @@
 import cn.idev.excel.util.ListUtils;
 import cn.idev.excel.write.handler.CellWriteHandler;
 import cn.idev.excel.write.handler.context.CellWriteHandlerContext;
+import cn.idev.excel.write.merge.DynamicMergeStrategy;
 import cn.idev.excel.write.merge.LoopMergeStrategy;
 import cn.idev.excel.write.style.HorizontalCellStyleStrategy;
 import cn.idev.excel.write.style.column.LongestMatchColumnWidthStyleStrategy;
@@ -613,6 +610,60 @@ public void dynamicHeadWrite() {
             .doWrite(data());
     }
 
+    /**
+     * 动态头，实时生成头写入
+     * 指定列值相同时合并
+     */
+    @Test
+    public void customHeadReadAndDynamicMergeStrategy() {
+        String fileName = TestFileUtil.getPath() + "customHeadRead" + System.currentTimeMillis() + ".xlsx";
+        List<Map<Integer, String>> maps = yearData();
+        EasyExcel.write(fileName)
+            .head(yearHead())
+            .sheet("模板")
+            .registerWriteHandler(new DynamicMergeStrategy(0,maps.size()))
+            .registerWriteHandler(new DynamicMergeStrategy(2,maps.size()))
+            .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
+            .doWrite(maps);
+    }
+
+    public List<List<String>> yearHead() {
+        List<List<String>> head = new ArrayList<>();
+        for (int i = 0; i < 12; i++) {
+            List<String> h = new ArrayList<>();
+            if(i<3){
+                h.add("第一季度");
+            }
+            if(i>=3&&i<6){
+                h.add("第二季度");
+            }
+            if(i>=6&&i<9){
+                h.add("第三季度");
+            }
+            if(i>=9){
+                h.add("第四季度");
+            }
+            h.add("第" + (i + 1) + "月");
+            head.add(h);
+        }
+        return head;
+    }
+    public List<Map<Integer, String>> yearData() {
+        List<Map<Integer, String>> data = new ArrayList<>();
+        for (int i = 0; i < 100; i++) {
+            Map<Integer, String> map = new HashMap<>();
+            for (int j = 0; j < 12; j++) {
+                if(i<20){
+                    map.put( j , "第" + (j + 1) + "月"+"前20条数据");
+                }else {
+                    map.put( j , "第" + (j + 1) + "月");
+                }
+
+            }
+            data.add(map);
+        }
+        return data;
+    }
     /**
      * 自动列宽(不太精确)
      * <p>