java实现easyexcel填充数据并合并相同列属性的工具类

以下是一个示例Java类，演示如何使用EasyExcel库来填充数据并合并相同列属性：

import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.alibaba.excel.metadata.CellData;
import com.alibaba.excel.metadata.CellExtra;
import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.metadata.property.ExcelContentProperty;
import com.alibaba.excel.util.StringUtils;
import com.alibaba.excel.write.merge.AbstractMergeStrategy;
import com.alibaba.excel.write.metadata.holder.WriteSheet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.*;

public class EasyExcelUtil {

    private static final Logger LOGGER = LoggerFactory.getLogger(EasyExcelUtil.class);

    /**
     * 填充数据
     * @param filePath 文件路径
     * @param sheetName 工作表名称
     * @param data 数据
     */
    public static void fillData(String filePath, String sheetName, List<List<String>> data) {
        EasyExcel.write(filePath)
                .sheet(sheetName)
                .registerWriteHandler(new MergeStrategy())
                .registerWriteHandler(new CustomHeadWriteHandler())
                .doWrite(data);
    }

    /**
     * 自定义合并策略
     */
    private static class MergeStrategy extends AbstractMergeStrategy {

        private Map<Integer, List<Integer>> mergeMap = new HashMap<>();

        @Override
        protected void merge(SheetMergeProperties sheetMergeProperties) {
            Integer columnIndex = sheetMergeProperties.getColumnIndex();
            List<Integer> mergeIndexes = mergeMap.get(columnIndex);
            if (mergeIndexes == null) {
                mergeIndexes = new ArrayList<>();
                mergeMap.put(columnIndex, mergeIndexes);
            }
            mergeIndexes.add(sheetMergeProperties.getRowIndex());
        }

        @Override
        public void afterSheetCreate(WriteSheet writeSheet, AnalysisContext analysisContext) {
            super.afterSheetCreate(writeSheet, analysisContext);
            mergeMap.clear();
        }

        @Override
        public void afterSheetDispose(WriteSheet writeSheet, AnalysisContext analysisContext) {
            super.afterSheetDispose(writeSheet, analysisContext);
            mergeMap.clear();
        }

        @Override
        public void addContent(List<List<String>> content, WriteSheet writeSheet, AnalysisContext analysisContext) {
            for (Map.Entry<Integer, List<Integer>> entry : mergeMap.entrySet()) {
                Integer columnIndex = entry.getKey();
                List<Integer> mergeIndexes = entry.getValue();
                mergeColumn(content, columnIndex, mergeIndexes);
            }
        }

        private void mergeColumn(List<List<String>> content, Integer columnIndex, List<Integer> mergeIndexes) {
            if (mergeIndexes.size() <= 1) return;
            Integer rowIndex = mergeIndexes.get(0);
            String value = content.get(rowIndex).get(columnIndex);
            for (int i = 1; i < mergeIndexes.size(); i++) {
                Integer nextRowIndex = mergeIndexes.get(i);
                String nextValue = content.get(nextRowIndex).get(columnIndex);
                if (!StringUtils.isEmpty(nextValue) && !nextValue.equals(value)) {
                    LOGGER.warn("Cannot merge cells due to different values in column[{}]: '{}' != '{}'", columnIndex, value, nextValue);
                    return;
                }
            }
            for (int i = 1; i < mergeIndexes.size(); i++) {
                Integer nextRowIndex = mergeIndexes.get(i);
                content.get(nextRowIndex).set(columnIndex, null);
            }
        }

    }

    /**
     * 自定义表头写入处理器
     */
    private static class CustomHeadWriteHandler extends AnalysisEventListener<List<String>> {

        private Map<Integer, String> headMap = new HashMap<>();

        @Override
        public void invokeHead(Map<Integer, CellData> headMap, AnalysisContext context) {
            super.invokeHead(headMap, context);
            this.headMap.clear();
            for (Map.Entry<Integer, CellData> entry : headMap.entrySet()) {
                this.headMap.put(entry.getKey(), entry.getValue().getStringValue());
            }
        }

        @Override
        public void extra(CellExtra extra, AnalysisContext context) {
            super.extra(extra, context);
            if (extra.getType() == CellExtraTypeEnum.MERGE) {
                mergeHead(extra.getRowIndex(), extra.getColumnIndex(), extra.getRowIndex() + extra.getRowSpan() - 1, extra.getColumnIndex() + extra.getColSpan() - 1);
            }
        }

        private void mergeHead(Integer startRowIndex, Integer startColumnIndex, Integer endRowIndex, Integer endColumnIndex) {
            if (startRowIndex.equals(endRowIndex)) {
                String value = headMap.get(startColumnIndex);
                if (value != null) {
                    for (int i = startColumnIndex + 1; i <= endColumnIndex; i++) {
                        String nextValue = headMap.get(i);
                        if (!StringUtils.isEmpty(nextValue) && !nextValue.equals(value)) {
                            LOGGER.warn("Cannot merge column headers due to different values in row[{}]: '{}' != '{}'", startRowIndex, value, nextValue);
                            return;
                        }
                    }
                    for (int i = startColumnIndex + 1; i <= endColumnIndex; i++) {
                        headMap.remove(i);
                    }
                }
            } else if (startColumnIndex.equals(endColumnIndex)) {
                String value = headMap.get(startColumnIndex);
                if (value != null) {
                    for (int i = startRowIndex + 1; i <= endRowIndex; i++) {
                        String nextValue = headMap.get(i);
                        if (!StringUtils.isEmpty(nextValue) && !nextValue.equals(value)) {
                            LOGGER.warn("Cannot merge row headers due to different values in column[{}]: '{}' != '{}'", startColumnIndex, value, nextValue);
                            return;
                        }
                    }
                    for (int i = startRowIndex + 1; i <= endRowIndex; i++) {
                        headMap.remove(i);
                    }
                }
            }
        }

        @Override
        public void invoke(List<String> data, AnalysisContext context) {
            if (context.readRowHolder().getRowIndex() == 0) {
                for (int i = 0; i < data.size(); i++) {
                    String value = data.get(i);
                    if (value != null) {
                        headMap.put(i, value);
                    }
                }
            }
        }

        @Override
        public void onException(Exception exception, AnalysisContext context) throws Exception {
            super.onException(exception, context);
            LOGGER.error("Exception occurred during analysis", exception);
        }

        @Override
        public void doAfterAllAnalysed(AnalysisContext context) {
            headMap.clear();
        }

        @Override
        public void onException(Exception exception, AnalysisContext context, List<ExcelContentProperty> list) throws Exception {
            super.onException(exception, context, list);
            LOGGER.error("Exception occurred during analysis", exception);
        }

        @Override
        public boolean hasNext(AnalysisContext context) {
            return super.hasNext(context);
        }

        @Override
        public List<List<String>> invokeHead(Map<Integer, CellData> headMap, Head head, AnalysisContext context) {
            return super.invokeHead(headMap, head, context);
        }

    }

}

这个工具类包括两个主要的功能：

- `fillData`方法：使用EasyExcel库将数据填充到指定的Excel工作表中。该方法接收三个参数：文件路径、工作表名称和数据列表。它还注册了一个自定义的合并策略和一个自定义的表头写入处理器。
- `MergeStrategy`类：合并策略是一个实现`AbstractMergeStrategy`抽象类的内部类。它使用一个`mergeMap`来跟踪要合并的列和行，然后在`addContent`方法中执行实际的合并操作。
- `CustomHeadWriteHandler`类：表头写入处理器是一个实现`AnalysisEventListener`接口的内部类。它用来处理表头合并和异常处理。

使用这个工具类非常简单。只需调用`fillData`方法并传递文件路径、工作表名称和数据列表即可。例如：

List<List<String>> data = new ArrayList<>();
// 添加数据
EasyExcelUtil.fillData("test.xlsx", "Sheet1", data);

这个示例只是一个简单的例子，您可以根据自己的需求对这个工具类进行修改和扩展。