java 将三层树结构数据导出为excel

### Java 实现三层树形结构数据导出至 Excel 的方法 以下是基于 Apache POI 库实现将三层树形结构数据导出到 Excel 文件的示例代码。此代码假设每层节点具有特定属性（如 `hierarchy` 和子节点列表），并通过递归方式构建表格。 #### 示例代码 ```java import org.apache.poi.ss.usermodel.*; import org.apache.poi.xssf.usermodel.XSSFWorkbook; import java.io.FileOutputStream; import java.io.IOException; import java.util.List; public class TreeToExcelExporter { public static void exportTreeData(List<TreeNode> rootNodes, String filePath) throws IOException { Workbook workbook = new XSSFWorkbook(); Sheet sheet = workbook.createSheet("Tree Data"); // 设置表头 Row headerRow = sheet.createRow(0); String[] headers = {"层级", "物料编码", "物料名称", "基础数量", "使用数量", "BOM版本", "默认BOM"}; for (int i = 0; i < headers.length; i++) { Cell cell = headerRow.createCell(i); cell.setCellValue(headers[i]); } int rowIndex = 1; for (TreeNode node : rootNodes) { writeNode(sheet, node, rowIndex++); } try (FileOutputStream fileOut = new FileOutputStream(filePath)) { workbook.write(fileOut); } workbook.close(); } private static void writeNode(Sheet sheet, TreeNode node, int rowIndex) { Row row = sheet.createRow(rowIndex); row.createCell(0).setCellValue(node.getHierarchy()); row.createCell(1).setCellValue(node.getMaterialCode() != null ? node.getMaterialCode() : ""); row.createCell(2).setCellValue(node.getMaterialName() != null ? node.getMaterialName() : ""); row.createCell(3).setCellValue(node.getMaterialNum() != null ? node.getMaterialNum().toString() : ""); row.createCell(4).setCellValue(node.getUseAmount() != null ? node.getUseAmount().toString() : ""); row.createCell(5).setCellValue(node.getVersion() != null ? node.getVersion() : ""); row.createCell(6).setCellValue(node.isDefaults()); List<TreeNode> children = node.getChildren(); if (children != null && !children.isEmpty()) { for (TreeNode child : children) { writeNode(sheet, child, ++rowIndex); // 递归写入子节点 } } } public static void main(String[] args) throws IOException { // 构建测试数据 TreeNode rootNode1 = new TreeNode("L1"); TreeNode childNode1_1 = new TreeNode("L2").setMaterialCode("M1").setMaterialName("Item1"); TreeNode childNode1_2 = new TreeNode("L2").setMaterialCode("M2").setMaterialName("Item2"); rootNode1.addChild(childNode1_1).addChild(childNode1_2); TreeNode grandChildNode1_1_1 = new TreeNode("L3").setMaterialCode("M3").setMaterialName("SubItem1"); childNode1_1.addChild(grandChildNode1_1_1); List<TreeNode> treeData = List.of(rootNode1); // 导出到文件 exportTreeData(treeData, "tree_data.xlsx"); } } class TreeNode { private String hierarchy; private String materialCode; private String materialName; private BigDecimal materialNum; private BigDecimal useAmount; private String version; private boolean defaults; private List<TreeNode> children; public TreeNode(String hierarchy) { this.hierarchy = hierarchy; } public String getHierarchy() { return hierarchy;} public String getMaterialCode() {return materialCode;} public String getMaterialName() {return materialName;} public BigDecimal getMaterialNum() {return materialNum;} public BigDecimal getUseAmount() {return useAmount;} public String getVersion() {return version;} public boolean isDefaults() {return defaults;} public TreeNode setMaterialCode(String materialCode) {this.materialCode = materialCode; return this;} public TreeNode setMaterialName(String materialName) {this.materialName = materialName; return this;} public TreeNode setMaterialNum(BigDecimal materialNum) {this.materialNum = materialNum; return this;} public TreeNode setUseAmount(BigDecimal useAmount) {this.useAmount = useAmount; return this;} public TreeNode setVersion(String version) {this.version = version; return this;} public TreeNode setDefaults(boolean defaults) {this.defaults = defaults; return this;} public List<TreeNode> getChildren() {return children;} public TreeNode addChild(TreeNode child){ if(this.children == null)this.children = List.newArrayList(); this.children.add(child); return this; } } ``` 上述代码通过递归遍历树形结构中的每一层节点，并将其对应的属性值填充到 Excel 表格中[^4]。 --- ### 关键点说明 1. **Apache POI** 是一种强大的 Java 工具库，用于操作 Microsoft Office 文档，支持 `.xlsx` 格式的读取和写入。 2. 上述代码实现了对树形结构数据的逐层展开，并按照指定列顺序输出到 Excel 中。 3. 如果需要扩展功能（如样式设置或复杂校验逻辑），可以进一步增强代码逻辑[^5]。 ---