easyexcel-导入(读取)(read)-示例及核心部件
这块内容有点多，单独拉出来，要不看着太乱。导入(读取)(read)-示例及核心部件
代码：
EasyExcel.read(file.getInputStream(), UserExcelVo.class, userListener).extraRead(CellExtraTypeEnum.MERGE)
.sheet(0) // 指定读取哪个sheet
.headRowNumber(1) // 指定标题行
.doRead(); // 执行读取
导入(读取)(read)-核心部件
以上面代码为例。
EasyExcel(EasyExcelFactory) # 入口
read() # read()方法用于构建workbook(工作簿)对象，new ExcelReaderBuilder()
public class EasyExcelFactory {
public static ExcelReaderBuilder read() {
return new ExcelReaderBuilder();
}
}
public class ExcelReaderBuilder extends AbstractExcelReaderParameterBuilder<ExcelReaderBuilder, ReadWorkbook> {
/**
* Workbook
*/
private final ReadWorkbook readWorkbook;
public ExcelReaderBuilder() {
this.readWorkbook = new ReadWorkbook();
}
}
doReadAll()
public class ExcelReaderBuilder extends AbstractExcelReaderParameterBuilder<ExcelReaderBuilder, ReadWorkbook> {
public void doReadAll() {
try (ExcelReader excelReader = build()) {
excelReader.readAll();
}
}
}
public class ExcelReader implements Closeable {
public void readAll() {
excelAnalyser.analysis(null, Boolean.TRUE);
}
}
public class ExcelAnalyserImpl implements ExcelAnalyser {
@Override
public void analysis(List<ReadSheet> readSheetList, Boolean readAll) {
try {
if (!readAll && CollectionUtils.isEmpty(readSheetList)) {
throw new IllegalArgumentException("Specify at least one read sheet.");
}
analysisContext.readWorkbookHolder().setParameterSheetDataList(readSheetList);
analysisContext.readWorkbookHolder().setReadAll(readAll);
try {
excelReadExecutor.execute();
} catch (ExcelAnalysisStopException e) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Custom stop!");
}
}
} catch (RuntimeException e) {
finish();
throw e;
} catch (Throwable e) {
finish();
throw new ExcelAnalysisException(e);
}
}
}
这里选XlsxSaxAnalyser这个实现类吧
public class XlsxSaxAnalyser implements ExcelReadExecutor {
@Override
public void execute() {
for (ReadSheet readSheet : sheetList) {
readSheet = SheetUtils.match(readSheet, xlsxReadContext);
if (readSheet != null) {
xlsxReadContext.currentSheet(readSheet);
parseXmlSource(sheetMap.get(readSheet.getSheetNo()), new XlsxRowHandler(xlsxReadContext));
// Read comments
readComments(readSheet);
// The last sheet is read
xlsxReadContext.analysisEventProcessor().endSheet(xlsxReadContext);
}
}
}
}
然后到这个类XlsxRowHandler，这里利用了策略模式，会根据xml差异的标签拿到对应的处置惩罚类来举行处置惩罚。
public class XlsxRowHandler extends DefaultHandler {
static {
CellFormulaTagHandler cellFormulaTagHandler = new CellFormulaTagHandler();
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.CELL_FORMULA_TAG, cellFormulaTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.X_CELL_FORMULA_TAG, cellFormulaTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.NS2_CELL_FORMULA_TAG, cellFormulaTagHandler);
CellInlineStringValueTagHandler cellInlineStringValueTagHandler = new CellInlineStringValueTagHandler();
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.CELL_INLINE_STRING_VALUE_TAG, cellInlineStringValueTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.X_CELL_INLINE_STRING_VALUE_TAG, cellInlineStringValueTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.NS2_CELL_INLINE_STRING_VALUE_TAG, cellInlineStringValueTagHandler);
CellTagHandler cellTagHandler = new CellTagHandler();
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.CELL_TAG, cellTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.X_CELL_TAG, cellTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.NS2_CELL_TAG, cellTagHandler);
CellValueTagHandler cellValueTagHandler = new CellValueTagHandler();
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.CELL_VALUE_TAG, cellValueTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.X_CELL_VALUE_TAG, cellValueTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.NS2_CELL_VALUE_TAG, cellValueTagHandler);
CountTagHandler countTagHandler = new CountTagHandler();
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.DIMENSION_TAG, countTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.X_DIMENSION_TAG, countTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.NS2_DIMENSION_TAG, countTagHandler);
HyperlinkTagHandler hyperlinkTagHandler = new HyperlinkTagHandler();
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.HYPERLINK_TAG, hyperlinkTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.X_HYPERLINK_TAG, hyperlinkTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.NS2_HYPERLINK_TAG, hyperlinkTagHandler);
MergeCellTagHandler mergeCellTagHandler = new MergeCellTagHandler();
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.MERGE_CELL_TAG, mergeCellTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.X_MERGE_CELL_TAG, mergeCellTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.NS2_MERGE_CELL_TAG, mergeCellTagHandler);
RowTagHandler rowTagHandler = new RowTagHandler();
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.ROW_TAG, rowTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.X_ROW_TAG, rowTagHandler);
XLSX_CELL_HANDLER_MAP.put(ExcelXmlConstants.NS2_ROW_TAG, rowTagHandler);
}
}
从上面代码找到RowTagHandler这个类，每剖析了一行数据后都会举行处置惩罚
public class RowTagHandler extends AbstractXlsxTagHandler {
@Override
public void endElement(XlsxReadContext xlsxReadContext, String name) {
XlsxReadSheetHolder xlsxReadSheetHolder = xlsxReadContext.xlsxReadSheetHolder();
RowTypeEnum rowType = MapUtils.isEmpty(xlsxReadSheetHolder.getCellMap()) ? RowTypeEnum.EMPTY : RowTypeEnum.DATA;
// It's possible that all of the cells in the row are empty
if (rowType == RowTypeEnum.DATA) {
boolean hasData = false;
for (Cell cell : xlsxReadSheetHolder.getCellMap().values()) {
if (!(cell instanceof ReadCellData)) {
hasData = true;
break;
}
ReadCellData<?> readCellData = (ReadCellData<?>)cell;
if (readCellData.getType() != CellDataTypeEnum.EMPTY) {
hasData = true;
break;
}
}
if (!hasData) {
rowType = RowTypeEnum.EMPTY;
}
}
xlsxReadContext.readRowHolder(new ReadRowHolder(xlsxReadSheetHolder.getRowIndex(), rowType,
xlsxReadSheetHolder.getGlobalConfiguration(), xlsxReadSheetHolder.getCellMap()));
xlsxReadContext.analysisEventProcessor().endRow(xlsxReadContext);
xlsxReadSheetHolder.setColumnIndex(null);
xlsxReadSheetHolder.setCellMap(new LinkedHashMap<>());
}
}
然后看endRow()方法
public class DefaultAnalysisEventProcessor implements AnalysisEventProcessor {
@Override
public void endRow(AnalysisContext analysisContext) {
if (RowTypeEnum.EMPTY.equals(analysisContext.readRowHolder().getRowType())) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Empty row!");
}
if (analysisContext.readWorkbookHolder().getIgnoreEmptyRow()) {
return;
}
}
dealData(analysisContext);
}
}
进入到dealData方法中
private void dealData(AnalysisContext analysisContext) {
ReadRowHolder readRowHolder = analysisContext.readRowHolder();
Map<Integer, ReadCellData<?>> cellDataMap = (Map)readRowHolder.getCellMap();
readRowHolder.setCurrentRowAnalysisResult(cellDataMap);
int rowIndex = readRowHolder.getRowIndex();
int currentHeadRowNumber = analysisContext.readSheetHolder().getHeadRowNumber();
boolean isData = rowIndex >= currentHeadRowNumber;
// Last head column
if (!isData && currentHeadRowNumber == rowIndex + 1) {
buildHead(analysisContext, cellDataMap);
}
// Now is data
for (ReadListener readListener : analysisContext.currentReadHolder().readListenerList()) {
try {
if (isData) {
readListener.invoke(readRowHolder.getCurrentRowAnalysisResult(), analysisContext);
} else {
readListener.invokeHead(cellDataMap, analysisContext);
}
} catch (Exception e) {
onException(analysisContext, e);
break;
}
if (!readListener.hasNext(analysisContext)) {
throw new ExcelAnalysisStopException();
}
}
}
这里可以看到，每剖析了一行数据后都会逐个调用监听器的invoke方法（包括easyexcel默认的监听器和我们自定义的监听器）
跟踪invoke()方法，选用ModelBuildEventListener这个实现类吧
进入到ModelBuildEventListener实现类，这个实现类是easyexcel自带的默认的监听器，这个监听器的主要作用是将excel的每行数据封装
public class ModelBuildEventListener implements IgnoreExceptionReadListener<Map<Integer, ReadCellData<?>>> {
@Override
public void invoke(Map<Integer, ReadCellData<?>> cellDataMap, AnalysisContext context) {
ReadSheetHolder readSheetHolder = context.readSheetHolder();
if (HeadKindEnum.CLASS.equals(readSheetHolder.excelReadHeadProperty().getHeadKind())) {
context.readRowHolder()
.setCurrentRowAnalysisResult(buildUserModel(cellDataMap, readSheetHolder, context));
return;
}
context.readRowHolder().setCurrentRowAnalysisResult(buildNoModel(cellDataMap, readSheetHolder, context));
}
}
进入到buildUserModel方法中
private Object buildUserModel(Map<Integer, ReadCellData<?>> cellDataMap, ReadSheetHolder readSheetHolder,
AnalysisContext context) {
ExcelReadHeadProperty excelReadHeadProperty = readSheetHolder.excelReadHeadProperty();
Object resultModel;
try {
resultModel = excelReadHeadProperty.getHeadClazz().newInstance();
} catch (Exception e) {
throw new ExcelDataConvertException(context.readRowHolder().getRowIndex(), 0,
new ReadCellData<>(CellDataTypeEnum.EMPTY), null,
"Can not instance class: " + excelReadHeadProperty.getHeadClazz().getName(), e);
}
Map<Integer, Head> headMap = excelReadHeadProperty.getHeadMap();
BeanMap dataMap = BeanMapUtils.create(resultModel);
for (Map.Entry<Integer, Head> entry : headMap.entrySet()) {
Integer index = entry.getKey();
Head head = entry.getValue();
String fieldName = head.getFieldName();
if (!cellDataMap.containsKey(index)) {
continue;
}
ReadCellData<?> cellData = cellDataMap.get(index);
Object value = ConverterUtils.convertToJavaObject(cellData, head.getField(),
ClassUtils.declaredExcelContentProperty(dataMap, readSheetHolder.excelReadHeadProperty().getHeadClazz(),
fieldName, readSheetHolder), readSheetHolder.converterMap(), context,
context.readRowHolder().getRowIndex(), index);
if (value != null) {
dataMap.put(fieldName, value);
}
}
return resultModel;
}
可以看到，先是通过反射创建对象，然后根据反射对各个对象赋值。
至此，excel的一行数据就被easyexcel默认的监听器剖析成了对应的java对象，然后我们在自定义的监听器中就能拿到这个对象并举行处置惩罚了。
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