From 1003fb7511f402878bbf3a3ed41ca7dbc274343f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=96=AF=E7=8B=82=E7=9A=84=E7=8B=AE=E5=AD=90li?=
 <15040126243@163.com>
Date: Tue, 31 May 2022 13:39:58 +0800
Subject: [PATCH] =?UTF-8?q?add=20=E6=96=B0=E5=A2=9E=20easyexcel=20?=
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---
 .../common/excel/annotation/CellMerge.java    |  25 ++++
 .../common/excel/core/CellMergeStrategy.java  | 114 ++++++++++++++++++
 2 files changed, 139 insertions(+)
 create mode 100644 ruoyi-common/ruoyi-common-excel/src/main/java/com/ruoyi/common/excel/annotation/CellMerge.java
 create mode 100644 ruoyi-common/ruoyi-common-excel/src/main/java/com/ruoyi/common/excel/core/CellMergeStrategy.java

diff --git a/ruoyi-common/ruoyi-common-excel/src/main/java/com/ruoyi/common/excel/annotation/CellMerge.java b/ruoyi-common/ruoyi-common-excel/src/main/java/com/ruoyi/common/excel/annotation/CellMerge.java
new file mode 100644
index 00000000..1dd2b82f
--- /dev/null
+++ b/ruoyi-common/ruoyi-common-excel/src/main/java/com/ruoyi/common/excel/annotation/CellMerge.java
@@ -0,0 +1,25 @@
+package com.ruoyi.common.excel.annotation;
+
+
+import com.ruoyi.common.excel.core.CellMergeStrategy;
+
+import java.lang.annotation.*;
+
+/**
+ * excel 列单元格合并(合并列相同项)
+ *
+ * 需搭配 {@link CellMergeStrategy} 策略使用
+ *
+ * @author Lion Li
+ */
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+@Inherited
+public @interface CellMerge {
+
+	/**
+	 * col index
+	 */
+	int index() default -1;
+
+}
diff --git a/ruoyi-common/ruoyi-common-excel/src/main/java/com/ruoyi/common/excel/core/CellMergeStrategy.java b/ruoyi-common/ruoyi-common-excel/src/main/java/com/ruoyi/common/excel/core/CellMergeStrategy.java
new file mode 100644
index 00000000..1c7104fb
--- /dev/null
+++ b/ruoyi-common/ruoyi-common-excel/src/main/java/com/ruoyi/common/excel/core/CellMergeStrategy.java
@@ -0,0 +1,114 @@
+package com.ruoyi.common.excel.core;
+
+import com.alibaba.excel.metadata.Head;
+import com.alibaba.excel.write.merge.AbstractMergeStrategy;
+import com.ruoyi.common.excel.annotation.CellMerge;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.SneakyThrows;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.collections4.CollectionUtils;
+import org.apache.poi.ss.usermodel.Cell;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.util.CellRangeAddress;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * 列值重复合并策略
+ *
+ * @author Lion Li
+ */
+@AllArgsConstructor
+@Slf4j
+public class CellMergeStrategy extends AbstractMergeStrategy {
+
+	private List<?> list;
+	private boolean hasTitle;
+
+	@Override
+	protected void merge(Sheet sheet, Cell cell, Head head, Integer relativeRowIndex) {
+		List<CellRangeAddress> cellList = handle(list, hasTitle);
+		// judge the list is not null
+		if (CollectionUtils.isNotEmpty(cellList)) {
+			// the judge is necessary
+			if (cell.getRowIndex() == 1 && cell.getColumnIndex() == 0) {
+				for (CellRangeAddress item : cellList) {
+					sheet.addMergedRegion(item);
+				}
+			}
+		}
+	}
+
+	@SneakyThrows
+	private static List<CellRangeAddress> handle(List<?> list, boolean hasTitle) {
+		List<CellRangeAddress> cellList = new ArrayList<>();
+		if (CollectionUtils.isEmpty(list)) {
+			return cellList;
+		}
+		Class<?> clazz = list.get(0).getClass();
+		Field[] fields = clazz.getDeclaredFields();
+		// 有注解的字段
+		List<Field> mergeFields = new ArrayList<>();
+		List<Integer> mergeFieldsIndex = new ArrayList<>();
+		for (int i = 0; i < fields.length; i++) {
+			Field field = fields[i];
+			if (field.isAnnotationPresent(CellMerge.class)) {
+				CellMerge cm = field.getAnnotation(CellMerge.class);
+				mergeFields.add(field);
+				mergeFieldsIndex.add(cm.index() == -1 ? i : cm.index());
+			}
+		}
+		// 行合并开始下标
+		int rowIndex = hasTitle ? 1 : 0;
+		Map<Field, RepeatCell> map = new HashMap<>();
+		// 生成两两合并单元格
+		for (int i = 0; i < list.size(); i++) {
+			for (int j = 0; j < mergeFields.size(); j++) {
+				Field field = mergeFields.get(j);
+				String name = field.getName();
+				String methodName = "get" + name.substring(0, 1).toUpperCase() + name.substring(1);
+				Method readMethod = clazz.getMethod(methodName);
+				Object val = readMethod.invoke(list.get(i));
+
+				int colNum = mergeFieldsIndex.get(j);
+				if (!map.containsKey(field)) {
+					map.put(field, new RepeatCell(val, i));
+				} else {
+					RepeatCell repeatCell = map.get(field);
+					Object cellValue = repeatCell.getValue();
+					if (cellValue == null || "".equals(cellValue)) {
+						// 空值跳过不合并
+						continue;
+					}
+					if (cellValue != val) {
+						if (i - repeatCell.getCurrent() > 1) {
+							cellList.add(new CellRangeAddress(repeatCell.getCurrent() + rowIndex, i + rowIndex - 1, colNum, colNum));
+						}
+						map.put(field, new RepeatCell(val, i));
+					} else if (i == list.size() - 1) {
+						if (i > repeatCell.getCurrent()) {
+							cellList.add(new CellRangeAddress(repeatCell.getCurrent() + rowIndex, i + rowIndex, colNum, colNum));
+						}
+					}
+				}
+			}
+		}
+		return cellList;
+	}
+
+	@Data
+	@AllArgsConstructor
+	static class RepeatCell {
+
+		private Object value;
+
+		private int current;
+
+	}
+}